Preparative fluorous mixture synthesis of diazonium-functionalized oligo(phenylene vinylene)s

Article abstract of DOI:10.1021/jo048051s

(Chemical Equation Presented) A series of building blocks for the synthesis of oligo(phenylene vinylene)s (OPVs) and hybrid oligomers were prepared, and alternating Heck coupling and Horner-Wadswoth-Emmons (HWE) reactions were used to couple the building blocks. Model studies were carried out to optimize the reaction strategies. The products were made to bear aryl diazonium functionalities that allow them to be used as surface grafting moieties in hybrid silicon/molecule assemblies. A library of OPV and hybrid oligomer tetramers was synthesized using fluorous mixture synthesis (FMS). The fluorous tags, which are secondary amines bearing different numbers of fluorine atoms, were synthesized and used as phase tags in mixture synthesis. The tags and substrates were anchored together by triazene linkages. The mixture synthesis was monitored by analytical HPLC on a fluorous column, and isolation of final OPV and hybrid oligomer tetramers was achieved by preparative HPLC. At the end of the FMS, after demixing, the tagged products were detagged by cleaving the triazene linkage and generating a series of aryl diazonium compounds. The fluorous tags could be recovered and reused. The NMR spectra of the 1-aryl-3,3-dialkyltriazenes are discussed.

Full text of DOI:10.1021/jo048051s

Preparative Fluorous Mixture Synthesis of
Diazonium-Functionalized Oligo(phenylene vinylene)s
Huahua Jian and James M. Tour*
Department of Chemistry, Department of Mechanical Engineering and Materials Science and
Center for Nanoscale Science and Technology, MS-222, Rice University, 6100 South Main Street,
Houston, Texas 77005
tour@rice.edu
Received November 2, 2004
A series of building blocks for the synthesis of oligo(phenylene vinylene)s (OPVs) and hybrid
oligomers were prepared, and alternating Heck coupling and Horner-Wadswoth-Emmons (HWE)
reactions were used to couple the building blocks. Model studies were carried out to optimize the
reaction strategies. The products were made to bear aryl diazonium functionalities that allow them
to be used as surface grafting moieties in hybrid silicon/molecule assemblies. A library of OPV and
hybrid oligomer tetramers was synthesized using fluorous mixture synthesis (FMS). The fluorous
tags, which are secondary amines bearing different numbers of fluorine atoms, were synthesized
and used as phase tags in mixture synthesis. The tags and substrates were anchored together by
triazene linkages. The mixture synthesis was monitored by analytical HPLC on a fluorous column,
and isolation of final OPV and hybrid oligomer tetramers was achieved by preparative HPLC. At
the end of the FMS, after demixing, the tagged products were detagged by cleaving the triazene
linkage and generating a series of aryl diazonium compounds. The fluorous tags could be recovered
and reused. The NMR spectra of the 1-aryl-3,3-dialkyltriazenes are discussed.
Introduction
interest, nowadays combinatorial synthesis is shifting to
make more focused libraries.6 Organic molecules that
possess conjugated systems have been widely studied for
their electronic and optical properties.7 In recent years,
several conjugated oligomer libraries have been made,
such as oligo(phenylene ethynylene)s,8 oligothiophenes,9
oligo(triacetylene)s, and oligo(phenylene triacetylene)s.10
Combinatorial synthesis is a tool to generate libraries
of materials1 and catalysts.2 A large number of new
organic materials have been made combinatorially, such
as dendrimers,3 fluorescent dyes,4 and conjugated oligo-
mers.5 Instead of making a huge number of similar
molecules and taking great effort to find the ones of
10.1021/jo048051s CCC: $30.25 © 2005 American Chemical Society
Published on Web 03/26/2005
3396
J. Org. Chem. 2005, 70, 3396-3424

Synthesis of Diazonium-Functionalized Oligo(phenylenevinylene)s
SCHEME 1
The poly(phenylene vinylenes) (PPVs) constitute a
class of interesting conjugated systems. They show a
range of electrical and optical properties11,12 that make
them useful as light-emitting diodes (LEDs), semicon-
ductive or photoconductive devices, and in related ap-
plications.13,14 However, the solubility of PPVs limited
their processing and further development.15 Although
soluble PPVs have been made, the structure of PPV
backbones cannot be finely tuned to achieve certain
functions. Hence oligo(phenylene vinylene)s (OPVs) were
developed as substitutes for PPVs because they have
similar properties to PPVs and their structure can be
finely controlled.14 Changing functional groups on the
backbone of an OPV will result in a change of its
electrical and optical performance. Unfortunately, how
the substituents will affect the physical properties of
the OPV is not always predictable. Most new ma-
terials are found by screening. For conjugated oligo-
mers, the sequence of repeat units also has an impact
on their properties.16 In this paper, we describe our
effort to synthesize a library of OPV tetramers and hy-
brid oligomers on a preparative scale so that they can
be screened in future work. To our knowledge, this is
the first OPV library synthesized by combinatorial
chemistry.
SCHEME 2
When attached to surfaces, a direct M-C bond was
formed. This attachment mode is complementary to the
conventional thiolate “alligator clip” for the attachment
of molecules to surfaces because the M-S-C moiety has
one additional σ bond between the metal surface and the
conjugate molecule, possibly hindering electronic trans-
port between them. Also, the surface-molecule bonds
formed by deposition of aryl diazoniums give monolayers
on complementary technologically interesting surfaces,
such as silicon and GaAs.18 Hence, OPVs and hybrid
oligomers bearing diazonium functionality became the
targets of the combinatorial-based syntheses described
here.
Molecules derived from aryl diazonium salts have been
assembled on metal and semiconductor surfaces.17,18
Combinatorial synthesis dramatically increases through-
put by binding the substrates to a resin (for solid-
supported combinatorial synthesis) or phase-tags (for
solution-phase combinatorial synthesis). The linkage is
important since it will have to tolerate all transforma-
tions and should be easily cleaved at the end of the
synthesis. We chose the widely used triazene moiety as
the linkage for both solid- and solution-phase combina-
torial syntheses,19-21 Scheme 1 shows the formation of a
triazene linkage.
Since both the amine and diazonium group are pro-
tected at the same time, triazenes can serve as protection
groups for both functionalities.22 Triazenes have been
converted to aryl diazonium salts, with further reactions
carried out in situ,23 and to other functionalities.24
Scheme 2 shows the most common conversions of the
triazene linker in combinatorial synthesis applications.
These processes, while cleaving the triazene linkage, also
release the linked products from their solid support (for
solid-supported synthesis) or phase tag (for solution
phase synthesis).
(1) For a review of combinatorial chemistry in materials science,
see: (a) Jandeleit, B.; Schaefer, D. J.; Powers, T. S.; Turner, H. W.;
Weinberg, W. H. Angew. Chem., Int. Ed. 1999, 38, 2494-2532. A recent
example, synthesis of a library of liquid crystals. (b) Deeg, O.; Bauerle,
P. Org. Biomol. Chem. 2003, 1, 1609-1624.
(2) For reviews of combinatorial chemistry for catalysts synthesis
and screening, see: (a) Jandeleit, B.; Schaefer, D. J.; Powers, T. S.;
Turner, H. W.; Weinberg, W. H. Angew. Chem., Int. Ed. 1999, 38,
2494-2532. (b) Senkan, S. Angew. Chem., Int. Ed. 2001, 40, 312-329.
(c) Tian, J.; Coates, G. W. Angew. Chem., Int. Ed. 2000, 39, 3626-
3629.
(3) Hecht, S.; Vladimirov, N.; Frechet, J. M. J. J. Am. Chem. Soc.
2001, 123, 18-25.
(4) Schiedel, M.-S.; Briehn, C. A.; Bauerle, P. Angew. Chem., Int.
Ed. 2001, 40, 4677-4680.
(5) Briehn, C. A.; Bauerle, P. Chem. Commun. 2002, 1015-1023.
(6) Mullin, R. Chem. Eng. News 2004, 82, 23-32.
(7) For recent reviews on conjugated polymers: (a) Friend, R. H.;
Gymer, R. W.; Holmes, A. B.; Burroughes, J. H.; Marks, R. N.; Taliani,
C.; Bradley, D. D. C.; Santos, D. A. D.; Bredas, J. L.; Logdlund, M.;
Salaneck, W. R. Nature 1999, 397, 121-128. (b) Burroughes, J. H.;
Bradley, D. D. C.; Brown, A. R.; Marks, R. N.; Mackay, K.; Friend, R.
H.; Burns, P. L.; Holmes, A. B. Nature 1990, 347, 539-541. (c) Yu, G.;
Gao, J.; Hummelen, J. C.; Wudl, F.; Heeger, A. J. Science 1995, 270,
1789-1791. (d) Hide, F.; Diaz-Garcia, M. A.; Schwartz, B. J.; Heeger,
A. J. Acc. Chem. Res. 1997, 30, 430-436.
(8) (a) Nelson, J. C.; Young, J. K.; Moore, J. S. J. Org. Chem. 1996,
61, 8160-8168. (b) Jones, L., II; Schumm, J. S.; Tour, J. M. J. Org.
Chem. 1997, 62, 1388-1410. (c) Hwang, J.-J.; Tour, J. M. Tetrahedron
2002, 58, 10387-10405.
As shown in Scheme 2, for aryl triazenes
(Ar-NdN-NR1R2), reductive cleavage of the triazene
(9) (a) Briehn, C. A.; Schiedel, M.-S.; Bonsen, E. M.; Schuhmann,
W.; Bauerle, P. Angew. Chem., Int. Ed. 2001, 40, 4680-4683. (b)
Schiedel, M. S.; Briehn, C. A.; Bauerle, P. J. Organomet. Chem. 2002,
653, 200-208. (c) Briehn, C. A.; Bauerle, P. J. Comb. Chem. 2002, 4,
457-469.
(16) Facchetti, A.; Yoon, M.-H.; Stern, C. L.; Katz, H. E.; Marks, T.
J. Angew. Chem., Int. Ed. 2003, 42, 3900-3903.
(17) Kosynkin, D. V.; Tour, J. M. Org. Lett. 2001, 3, 993-995.
(18) Stewart, M. P.; Maya, F.; Kosynkin, D. V.; Dirk, S. M.;
Stapleton, J. J.; McGuiness, C. L.; Allara, D. L.; Tour, J. M. J. Am.
Chem. Soc. 2004, 126, 370-378.
(10) Utesch, N. E.; Diederich, F.; Boudon, C.; Gisselbrecht, J. P.;
Gross, M. Helv. Chim. Acta 2004, 87, 698-718.
(11) Hide, F.; Diaz-Garcia, M. A.; Schwartz, B. J.; Heeger, A. J. Acc.
Chem. Res. 1997, 30, 430-436.
(19) Guillier, F.; Orain, D.; Bradley, M. Chem. Rev. 2000, 100, 2091-
2158.
(12) Burroughes, J. H.; Bradley, D. D. C.; Brown, A. R.; Marks, R.
N.; Mackay, K.; Friend, R. H.; Burns, P. L.; Holmes, A. B. Nature 1990,
347, 539-541.
(20) Bra¨se, S.; Dahmen, S.; Pfefferkorn, M. J. Comb. Chem. 2000,
2, 710-715.
(21) Comely, A. C.; Gibson, S. E. Angew. Chem., Int. Ed. 2001, 40,
1012-1032.
(13) Peng, Z.; Gharavi, A. R.; Yu, L. J. Am. Chem. Soc. 1997, 119,
4622-4632.
(22) Gross, M. L.; Blank, D. H.; Welch, W. M. J. Org. Chem. 1993,
58, 2104-2109.
(14) Martin, R. E.; Diederich, F. Angew. Chem., Int. Ed. 1999, 38,
1350-1377.
(23) Meijere, A.; Nuske, H.; Es-Sayed, M.; Labahn, T.; Shroen, M.;
Bra¨se, S. Angew. Chem., Int. Ed. 1999, 38, 3669-3672.
(24) Kimball, D. B.; Haley, M. M. Angew. Chem., Int. Ed. 2002, 41,
3338-3351.
(15) Muller, C. D.; Falcou, A.; Reckefuss, N.; Rojohn, M.; Wiederhirn,
V.; Rudati, P.; Nuyken, H. F. O.; Becker, H.; Meerholz, K. Nature 2003,
421, 829-833.
J. Org. Chem, Vol. 70, No. 9, 2005 3397

Jian and Tour
group gives aromatic hydrocarbons (Ar-H). This strategy
has been used in natural product synthesis.25 When used
in combinatorial chemistry, the triazene group is dis-
placed by a proton after treating the linkage with a
reductive acid.26 This is called traceless cleavage.21 Heat-
ing a molecule containing the triazene moiety in io-
domethane converts it into an aryl iodide, which provides
an active site for further chemistry.8 A non-reductive acid,
such as HOAc or trifluoroacetic acid (TFA), cleaves the
same bond formed during synthesis of triazene, giving
back the aryl diazonium salt and the amine.27,28 Although
there are a few cases in the combinatorial literature of
the conversion of triazene groups to synthesize aryl
diazonium salts,27 this conversion was limited to the
regeneration of diazonium functionalized resins.29,30 Our
work is the first to make aryl diazonium libraries.
In applying our earlier work8c to the synthesis of OPVs,
we found that the use of solid-phase organic synthesis
(SPOS) in combinatorial synthesis suffered from several
known bottlenecks, such as unfavorable heterogeneous
reaction kinetics, limited resin loading capacity, the need
for a large excess of reagent that cannot always be
recovered, and the necessity for releasing the product
from the resin in order to monitor the reaction progress.
Solution-phase combinatorial chemistry has become a
viable alternative to SPOS, since it has advantages of
both homogeneous reaction kinetics and combinatorial
high-throughput31 and includes soluble polymer-sup-
ported organic synthesis (SPSOS),32 biphasic catalysis,33
ionic liquids,34-36 fluorous synthesis,37 phase extraction,38
precipitation auxiliary labels,39 and others.
rous reverse phase silica gel (FluoroFlash) began to be
used for separation.43 FluoroFlash HPLC columns have
C8F17 functionalized silica gel as the stationary phase.
Therefore, the mobility of a molecule on this silica gel
depends on the number of fluorine atoms it possesses.
In a HPLC separation of a mixture of different fluorous
compounds, molecules with increasing fluorous content
have longer retention times. The use of fluorous HPLC
to isolate products allows light fluorous synthesis with
fewer fluorines (F% < 40 wt %).44 The compounds that
contain no fluorine atoms are treated as inert and have
no interaction with the FluoroFlash column.
FMS can be done in one-pot consecutive reactions,
which means mixed components are taken through a
multistep synthesis and separated at the end of the
synthesis. If we begin with a specific number of tagged
substrates, the same number of products is generated in
one-pot FMS. The library size one-pot FMS can generate
is limited. But the process is good for the synthesis of a
more focused library, such as preparative combinatorial
synthesis.
Combining FMS with split-parallel synthesis tech-
niques, larger libraries with more diversity can be
synthesized.45 In this technique, intermediates from FMS
sequences could be split into several portions and differ-
ent reactions are carried out on each portion.
At this stage, FMS addresses many of the SPOS
problems since reactions are done homogeneously; due
to the lipophilicity of the perfluoroalkyl chains, the
solubility of tagged substrates is equal to or better than
their untagged counterparts.40 In addition, reaction scale-
up is similar to ordinary solution-phase organic synthesis,
optimization of reaction protocols can be easier than
SPOS, the fluorous tags are stable in common organic
reactions and have minimal effect on the reactivity of the
tagged substrates, a large excess of reagents is not
required, and TLC, NMR, IR, and GC-MS can be used
to monitor the reaction process without cleaving the
products from their support.
Fluorous technologies for high-throughput organic
synthesis have been in development since the mid-
1990s.40 Fluorous synthesis is similar to solid-phase
synthesis in concept,37 yet it is more like traditional
solution phase synthesis in practice. In the earlier years
of fluorous mixture synthesis (FMS),41 purification of
products was done by fluorous extraction.42 A significant
advancement in FMS technology was made when fluo-
There are five stages involved in FMS,41 as shown
in Scheme 3 for our synthesis of OPV tetramers and
hybrid oligomers. (1) Tagging: a series of diazonium
functionalized aryl iodides (building blocks 1-4
(BB1-BB4)) are tagged separately with a correspond-
ing number of secondary amine fluorous tags.46 (2)
Mixing: the tagged substrates are mixed. (3) Synthe-
sis: the OPV oligomers are extended by alternating Heck
coupling and HWE reactions. (4) Demixing: the mixture
of tagged OPV tetramers are separated by fluorous
HPLC; since the fluorine content is known, the order of
separation can be predicted. (5) Detagging: the isolated
products with tags are converted to the final diazonium
salt OPV tetramer products by separately removing their
tags.
(25) Nicolaou, K. C.; Li, H.; Boddy, C. N. C.; Ramanjulu, J. M.; Yue,
T.-Y.; Natarajan, S.; Chu, X.-J.; Bra¨se, S.; Ru¨bsam, F. Chem. Eur. J.
1999, 5, 2584-2601.
(26) Kornblum, N.; Kelley, A. E.; Cooper, G. D. J. Am. Chem. Soc.
1952, 74, 3074-3076.
(27) Barbero, M.; Degani, L.; Diulgheroff, N.; Dughera, S.; Fochi,
R. Synthesis 2001, 2180-2190.
(28) Dahmen, S.; Bra¨se, S. Org. Lett. 2000, 2, 3563-3565.
(29) Bra¨se, S.; Enders, D.; Kobberling, J.; Avemaria, F. Angew.
Chem., Int. Ed. 1998, 37, 3413-3415.
(30) Bra¨se, S.; Schroen, M. Angew. Chem., Int. Ed. 1999, 38, 1071-
1073.
(31) An, H.; Cook, P. D. Chem. Rev. 2000, 100, 3311-3340.
(32) Toy, P. H.; Janda, K. D. Chem. Rev. 2000, 33, 546-554.
(33) Tzschucke, C. C.; Markert, C.; Bannwarth, W.; Roller, S.; Hebel,
A.; Haag, R. Angew. Chem., Int. Ed. 2002, 41, 3964-4000.
(34) Xu, L.; Chen, W.; Xiao, J. Organometallics 2000, 19, 1123-
1127.
(35) Hagiwara, H.; Shimizu, Y.; Hoshi, T.; Suzuki, T.; Ando, M.;
Ohkubo, K.; Yokoyama, C. Tetrahedron Lett. 2001, 42, 4349-4351.
(36) Bohm, V. P. W.; Herrmann, W. A. Chem. Eur. J. 2000, 6, 1017-
1025.
(37) Curran, D. P. Angew. Chem., Int. Ed. 1998, 37, 1174-1196.
(38) Cheng, S.; Comer, D. D.; Williams, J. P.; Myers, P. L.; Boger,
D. L. J. Am. Chem. Soc. 1996, 118, 2567-2573.
(39) Bosanac, T.; Yang, J.; Wilcox, C. S. Angew. Chem., Int. Ed. 2001,
40, 1875-1879.
(40) Zhang, W. Tetrahedron 2003, 59, 4475-4489.
(41) Luo, Z.; Zhang, Q.; Yoji, O.; Curran, D. P. Science 2001, 291,
1766-1769.
(42) Studer, A.; Hadida, S.; Ferritto, R.; Kim, S.-Y.; Jegar, P.; Wipf,
P.; Curran, D. P. Science 1997, 275, 823-826.
If we have n1 R1s, n2 R2s, n3 R3s and n4 R4s, by the
split-parallel technique,45 a library of n1 × n2 × n3 × n4
compounds could be made.
(43) Curran, D. P. Synlett 2001, 1488-1496.
(44) Curran, D. P.; Luo, Z. J. Am. Chem. Soc. 1999, 121, 9069-
9072.
(45) Zhang, W.; Luo, Z.; Chen, C. H.-T.; Curran, D. P. J. Am. Chem.
Soc. 2002, 124, 10443-10450.
(46) Chen, W.; Xu, L.; Xiao, J. Tetrahedron Lett. 2001, 42, 4275-
4278.
3398 J. Org. Chem., Vol. 70, No. 9, 2005

Synthesis of Diazonium-Functionalized Oligo(phenylenevinylene)s
SCHEME 3
An ethylene spacer was placed between the perfluoro-
alkyl chain and the benzene ring and a methylene spacer
between the amine and the benzene ring to minimize
effects of the perfluoroalkyl chain on the chemistry of the
substrate.
Scheme 6 shows the synthesis of the tag precursor
compound 4. It was made in two steps quantitatively
from 4-bromobenzyl bromide: amination of the benzyl
bromide using n-propylamine, followed by protection of
the benzylamine. In the first reaction, a large excess of
n-propylamine had to be used to limit tertiary amine and
quaternary ammonium salt formation. The excess n-
propylamine was recovered and reused in subsequent
amination reactions.
Heck coupling between bromide 4 and 1H,1H,2H-
perfluoroalkenes required an effective palladacycle cata-
lyst53 which generally proved to be superior to Pd(OAc)2.
Its structure and synthesis is shown in Scheme 7. Scheme
8 shows the synthesis of the fluoro tags in separate
reaction pots. Hydrogenation of the coupled alkenes
(5a-d) in separate reaction pots was done by a modified
literature procedure.46 Removal of the Boc groups on
6a-d in separate reactions gave secondary amines 7a-d
as fluorous tags for aryl iodides. Each fluorous tag was
synthesized separately and was used to tag different aryl
iodides separately.
Scheme 9 shows tagging of each of the aryl iodides in
separate pots. Each aryl diazonium salt 2 was tagged
with a different fluorine-containing tag 7. Treating the
solution of the diazonium salt and the amine with base
in acetonitrile completed the tagging; for the longer
perfluoroalkyl chain amines (7c and 7d), THF had to be
added to dissolve the amines.
SCHEME 4
Synthesis of Other Building Blocks. Our strategy
for growing OPV and hybrid oligomers was to use
alternating Heck and HWE reactions. Building blocks
were made separately, and put together sequentially to
make oligomers. Each internal building block had two
active sites, one for Heck coupling and one for HWE
reaction. The terminal building blocks had one active site
for either one of the two key reactions. The first building
block will be linked to a fluorous tag. The last building
block will serve to endcap the oligomer, so as to prevent
further growth of the chain. The diversity of the library
is achieved by substituting various functional groups on
the building blocks.
SCHEME 5
Results and Discussion
Synthesis of Fluorous Tags. The synthesis of the
fluorous tags began with formation of the diazonium salts
2a, 2b,47 2c, and 2d,48 achieved by treating the corre-
sponding substituted anilines under Doyle-Bryker con-
ditions,49 as shown in Scheme 4.
Except for 1b, which is commercially available, the
4-iodoanilines 1a,50 1c,51,52 and 1d52 were prepared by
iodination of substituted anilines. As an example, the
procedure for synthesizing 1a is shown in Scheme 5.
The chosen tag is composed of a perfluoroalkyl chain
and a secondary amine connected by a phenylene group.
To demonstrate this strategy, we made a library of
p-OPV tetramers and hybrid oligomers. The first building
block (BB1 in Scheme 3) of the tetramer is the tagged
substrate 8a-d, which contains aryl iodides as the Heck
coupling candidates. The second building block (BB2 in
Scheme 3) had a vinyl group to couple with the tagged
aryl iodide and an aldehyde group for further oligomer
growth. Four BB2s (9, 12, 16, and 19) were prepared,
bearing different functionalities.
The simplest BB2 is 4-vinylbenzaldehyde (9).54 As
shown in Scheme 10, both 4-bromostyrene and 4-chloro-
styrene were used to prepare 9 via a Grignard reagent.55
(47) Korzeniowski, S. H.; Leopold, A.; Beadle, J. R.; Ahern, M. F.;
Sheppard, W. A.; Khanna, R. K.; Gokel, G. W. J. Org. Chem. 1981, 46,
2153-2159.
(48) Hwang, J.-J.; Tour, J. M. Tetrahedron 2002, 58, 10387-10405.
(49) Doyle, M. P.; Bryker, W. J. J. Org. Chem. 1979, 44, 1572-1574.
(50) Alabaster, C. T.; Bell, A. S.; Campbell, S. F.; Ellis, P.; Hend-
erson, C. G.; Roberts, D. A.; Ruddock, K. S.; Samuels, G. M. R.;
Stefaniak, M. H. J. Med. Chem. 1988, 31, 2048-2056.
(51) Glendenning, M. E.; Goodby, J. W.; Hird, M.; Toyne, K. J. J.
Chem. Soc., Perkin Trans. 2 1999, 481-492.
(52) Krueger, G.; Keck, J.; Noll, K.; Pieper, H. Arzneim. Forsch./
Drug Res. 1984, 34, 1612-1624.
(53) Herrmann, W. A.; Brossmer, C.; Reisinger, C.-P.; Riermeier,
T. H.; Ofele, K.; Beller, M. Chem. Eur. J. 1997, 3, 1357-1364.
(54) Dale, W. J.; Starr, L.; Strobel, C. W. J. Am. Chem. Soc. 1961,
26, 2225-2227.
J. Org. Chem, Vol. 70, No. 9, 2005 3399

Jian and Tour
SCHEME 6
SCHEME 7
10 in four steps. Benzoic acid 22 was made from diiodide
10 via lithiation followed by a CO2 quenching; it was
reduced to the benzyl alcohol 23 in high yield. The benzyl
alcohol was converted to the benzyl bromide 24. 24 was
then converted to 25 via a Michaelis-Arbuzov reac-
tion64,65 in high yield. The same strategy was used to
synthesize 2,5-dibutoxy-functionalized BB3 28 (Scheme
16).
All the transformations in Scheme 16 have quite high
yields and nicely characterized products except for 27,
which is unstable in the solid state. As soon as solid 27
formed in air, the white crystal began to smoke and
become dark. In solution 27 was reasonably stable.
Conversion of 27 to 28 must be done before 27 decom-
poses and yields as high as 97% were obtained.
The last building block, BB4 (see Scheme 3) in the OPV
tetramer synthesis, is a group of functionalized styrenes.
Since BB4 has no functional groups for HWE reaction,
the oligomer growth would be endcapped after adding
BB4. Except for styrene, which is commercially available,
the other functionalized styrenes were synthesized.
The syntheses of BB4 3066 and 3167 are shown in
Scheme 17. 30 was made by a Negishi coupling68 from
29.69 4-Nitrostyrene 31 was synthesized according to a
literature procedure for dehydration.67
Scheme 18 shows synthesis of a BB4, 1,3-dinitrosty-
rene (34). 1,3-Dinitro-5-bromobenzene (32) was made by
bromination of 1,3-dinitrobenzene, following a modified
literature procedure.70,71 Stille- and Negishi-type reac-
tions were tried to make 34 from 32, neither of which
gave good yields because of incomplete conversion of 32.
Therefore 32 was subjected to halogen exchange to give
33 using the recently reported procedure by Buchwald.72
Negishi coupling on 33 gave 34 with complete consump-
tion of 33.
BB2 12 has two ethyl groups to increase solubility of
the oligomers (Scheme 11). Its synthesis began from
4-ethylacetophenone. Reduction of the ketone followed by
iodination of 1,4-diethylbenzene gave 10.56 Monolithiation
of 10 and quenching the aryllithium with anhydrous
DMF afforded benzaldehyde 11. A Stille coupling of 11
with vinyltributyltin57 gave 12.
2,5-Dialkoxy groups on OPV and PPV backbones are
known to not only increase the solubility of the deriva-
tives but also provide better photoreactivity and photo-
conductivity properties.7,14 BB2 16 is such a building
block, which was made in four steps from p-hydroquinone
(Scheme 12). Dibutylation of the hydroquinone dianion
gave 1,4-dibutoxybenzene 13, which was iodinated to give
14.58 Preparation of 15 followed Yu’s procedure.13 Com-
pound 16 was made from 15 via a Stille coupling.
3,4-Ethylenedioxylthiophene (EDOT) has attracted
interest as a building block for conducting polymers and
oligomers. Since it is a derivative of thiophene, it shares
thiophene’s electronic and optical properties59 and is
superior to thiophene in that it is more stable and easier
to process.60 To increase the diversity of the conjugated
oligomer library, we chose to make hybrid oligomers of
EDOT and OPV. Synthesis of EDOT containing BB2 19
(Scheme 13) began with commercially available EDOT.
The aldehyde 17 was prepared according to a literature
procedure.61 Bromination of 17 gave 18. A Stille coupling
reaction converted 18 to BB2 19.
Table 1 is a summary of the building blocks synthe-
sized. For the planned combinatorial synthesis of an OPV
tetramer and hybrid oligomer library, we have prepared
the following: four fluorous tags, four BB1s, four BB2s,
three BB3s, and four BB4s. If the split-parallel tech-
niques were fully applied, the total library size could be
4 × 4 × 3 × 4 ) 192.
The third building block (BB3 in Scheme 3) in oligomer
growth has a benzyl phosphonate group for HWE reac-
tion, and an aryl iodide for the Heck coupling. Three
kinds of BB3 were prepared for the library. The simplest
BB3 21 (Scheme 14) has no other substituents. Synthesis
of 2062 and 2163 followed literature procedures.
Another BB3 25 bears two ethyl groups to sol-
ubilize oligomers (Scheme 15). It was synthesized from
Model Studies. Reaction optimization is crucial for
combinatorial syntheses. For SPOS, the optimization of
reaction yield is necessary. For solution-phase combina-
(55) Leebrick, J. R.; Ramsden, H. E. J. Am. Chem. Soc. 1958, 23,
935-936.
(56) Yao, Y. Ph.D. Thesis, University of South Carolina, Columbia,
SC, 1998.
(64) Arbuzov, A. E. J. Russ. Phys. Chem. Soc. 1906, 38, 687.
(65) Michaelis, A.; Kaehne, R. Ber. 1898, 31, 1048.
(66) Murata, M.; Kawakita, K.; Asana, T.; Watanabe, S.; Masuda,
Y. Bull. Chem. Soc. Jpn. 2002, 75, 825-830.
(57) Seyferth, D.; Stone, F. G. A. J. Am. Chem. Soc. 1957, 79, 515-
517.
(58) Bao, Z.; Chen, Y.; Cai, R.; Yu, L. Macromolecules 1993, 26,
5281-5286.
(67) Zhuo, J.-C.; Wyler, H. Helv. Chim. Acta 1999, 82, 1122-1134.
(68) Negishi, E.; King, A. O.; Okukado, N. J. Org. Chem. 1977, 42,
1821-1823.
(59) Roncali, J. Chem. Rev. 1992, 92, 711-738.
(60) Sankaran, B.; Reynolds, J. R. Macromolecules 1997, 30, 2582-
2588.
(69) Jalil, A. A.; Kurono, N.; Tokuda, M. Tetrahedron 2002, 58,
7447-7484.
(61) Mohanakrishnan, A. K.; Hucke, A.; Lyon, M. A.; Lakshmikan-
tham, M. V.; Cava, M. P. Tetrahedron 1999, 55, 11745-11754.
(62) Sloviter, H. A. J. Am. Chem. Soc. 1949, 71, 3360-3361.
(63) Kung, H. F.; Lee, C.-W.; Zhuang, Z.-P.; Kung, M.-P.; Hou, C.;
Plossl, K. J. Am. Chem. Soc. 2001, 123, 12740-12741.
(70) Andrievskii, A. M.; Gorelik, M. V.; Avidon, S. V.; Al’tman, E.
S. Russ. J. Org. Chem. 1993, 29, 1519-1524.
(71) Jian, H.; Tour, J. M. J. Org. Chem. 2003, 68, 5091-5103.
(72) Klapars, A.; Buchward, S. L. J. Am. Chem. Soc. 2002, 124,
14844-14845.
3400 J. Org. Chem., Vol. 70, No. 9, 2005

Synthesis of Diazonium-Functionalized Oligo(phenylenevinylene)s
SCHEME 8
SCHEME 9
SCHEME 10
SCHEME 11
combination of base and solvent could make the reaction
efficient.
The model studies were expected to provide useful
information for both solid-phase and solution-phase
combinatorial synthesis. In the model studies, the tria-
zene linkage and fluorous tags were simplified to a 3,3-
diethyltriazene group. The yields were obtained using a
∼1:1 ratio of building blocks. The purpose of these model
studies was to determine if side reactions took place. We
expected that the yields would be higher in the combi-
natorial synthesis because an excess of one coupling
building block would be used.
The 3,3-diethyltriazene compounds, as models of BB1,
were synthesized from the aniline 1a (Scheme 19) or from
the diazonium salt 2b-d. Discussion about their NMR
spectra can be found below.
The first OPV trimer 37 (Scheme 20) was synthesized
by Heck coupling of 35b and 9, followed by HWE reaction
with 21. The poor solubility of 37 made further reaction
impractical. This model study established that OPV
trimers must bear solubilizing groups to enable further
functionalization.
The two ethyl groups on the backbone of OPV trimer
38 dramatically increased its solubility. Compound 38
was synthesized from HWE reaction of 36 with 25
(Scheme 21). It was extended to tetramer 39, which also
had good solubility.
Dimer 40 was made from 35b and 16 (Scheme 22). But
Heck coupling of 16 with aryl iodides always gave 1,1-
and cis-olefin isomers. The best yields for Heck coupling
between such substrates was 30-40% both in our hands
and in the literature.13 This dimer could not be used in
the combinatorial synthesis process until further opti-
mization was completed.
torial synthesis, even though it is not as important as
for SPOS, model studies are still necessary to test the
reaction conditions.
Unfortunately, there are no universal coupling condi-
tions that will work for every imaginable substrate. For
the attachment of a BB2 or BB4 to a BB1 or BB3
substrate using Heck coupling conditions, we always used
Pd(OAc)2 as the catalyst, but there are two ligand choices.
One is the traditional ligand P(o-tolyl)3. The other is a
ligand-free process using a tetrabutylammonium salt as
a phase-transfer catalyst. Usually either of these two
conditions could work. But there were some cases in
which one of them worked much better than the other.
Thus, the model studies proved essential. It is even more
important to do model studies for the attachment of a
BB3 to a BB2 using HWE reaction. Only the proper
J. Org. Chem, Vol. 70, No. 9, 2005 3401

Jian and Tour
SCHEME 12
SCHEME 13
SCHEME 16
SCHEME 14
SCHEME 15
vinylene groups in one conjugated oligomer backbone
could make a material with good optical and electrical
characteristics.74 The model study shown in Scheme 24
was done to make such an oligomer, 45. Dichloromethy-
lation of 1,4-dibutoxybenzene gave 43, which was sub-
jected to a substitution reaction to afford dicyano com-
pound 44. A Knoevenagel condensation between 44 and
19 gave hybrid oligomer 45. Compound 45 is sensitive
to acid, light, and air.
The last model study carried out was to make a
diazonium-functionalized trimer 48 (Scheme 25). This
trimer has an ethyl group for solubility, which came from
the BB1 35a. Heck coupling of 35a with 9, followed by
HWE reaction with 21, gave triazene trimer 47. The
triazene group was converted to the diazonium salt with
HBF4. The triazene acted as a protected form of the
diazonium group in these processes. With the information
provided to us by the model studies we moved on to the
combinatorial syntheses of the OPVs.
Mixture Synthesis. For the two basic coupling reac-
tions involved in our synthetic strategy (Heck reaction
and HWE reaction), similar substrates require similar
reaction conditions. Using mixture synthesis technology
to grow OPV oligomers takes advantage of this fact. Four
reactions are done in one pot. The following syntheses
were carried out by starting with mixtures of four
substrates 8a-d. Each coupling reaction generated a
A model study of EDOT-based BB2 19 is shown in
Scheme 23. Heck coupling of aryl iodide 35b and 19 gave
41. The yield (72%) was better than the reactions between
aryl iodides and styrenes. However, under common HWE
conditions (NaH in DME), reaction between dimer 41 and
BB3 21 did not give clean trimer product 42. After trying
different combinations of bases (t-BuOK and NaH) and
solvents (DME, THF, and DMF), we found that NaH in
DMF gave the best yield. The electron-rich EDOT-
containing hybrid oligomers, such as trimer 42, are
unstable in air and sensitive to acid.
The presence of cyano groups on the vinylene linkage
of the electron-rich OPV backbone greatly lowers the
electronic band gap of the oligomer.73 It is believed that
incorporation of 2,5-dialkoxyphenylene, EDOT, and cyano
(73) Sotzing, G. A.; Thomas, C. A.; Reynolds, J. R.; Steel, P. J.
Macromolecules 1998, 31, 3750-3752.
(74) Pepitone, M. F.; Hardaker, S. S.; Gregory, R. V. Chem. Mater.
2003, 15, 557-563.
3402 J. Org. Chem., Vol. 70, No. 9, 2005

Synthesis of Diazonium-Functionalized Oligo(phenylenevinylene)s
SCHEME 17
SCHEME 18
55a-d have higher solubility than their untagged coun-
terparts because of the lipophilicity of the tags (perfluo-
roalkyl chains). Analytical HPLC showed four nicely
distributed product peaks. However, after extension to
the tetramers 56a-d, the solubility of the mixture was
too low to be isolated by preparative HPLC.
Scheme 30 shows the synthesis of hybrid oligomers of
phenylene-vinylene and the EDOT derivative. The mix-
ture 8a-d coupled with 19 to give dimers 57a-d.
Extending these dimers to trimers 58a-d followed the
conditions of the model study from Scheme 24. The
trimers were extended to tetramers 59a-d by coupling
with p-nitrostyrene (31). The solubilities of EDOT con-
taining hybrid oligomers were much higher than those
of the OPVs. Even without any solubilizing group on the
oligomer backbone, the tetramers were easily dissolved
in common organic solvents.
The trimer mixture 58a-d was split into three por-
tions. In addition to the extension to a mixture of
tetramers with a nitro terminus, as shown in Scheme 30,
the trimer mixture was also coupled with styrene or
carbomethoxy styrene derivative 30 to give other tet-
ramer mixtures (Scheme 31).
The EDOT-containing tetramers 59a-d, 60a-d, and
61a-d were not successfully separated by using
H2O-CH3CN or H2O-MeOH solvent mixtures because
of their poor solubility in these systems. The prepara-
tive separation could however be achieved by using a
THF-based system. Except for 59d, each isolated fraction
was a mixture of desired product and polymers. The
EDOT-containing hybrid oligomers are known to be
unstable because of their low oxidation potentials.75 The
free radicals generated by THF hydroperoxides during
separation may have contributed to the polymerization
of EDOT-containing products, although mass spectro-
metric analysis verified the presence of the desired
tetramers.
The preceding mixture syntheses all generated mix-
tures of OPV tetramers (or hybrid oligomers with EDOT).
The final products were isolated at the end of synthetic
route by preparative HPLC. The isolated tetramers with
their tags were then detagged separately by HBF4 to give
diazonium salts.
mixture of four fluoro-tagged products. Each mixture
synthesis reaction was monitored by analytical HPLC on
a FluoroFlash column. The compounds with no fluorous
content, which include excess reagents, building blocks
and side products, had no interaction with the fluorous
column and eluted first. The intermediate mixtures were
usually neither isolated nor characterized. Therefore the
yields of the individual reaction steps were not calculated.
Only the final products were isolated by preparative
HPLC on a FluoroFlash column. After isolation, the
tetramers with fluoro tags were fully characterized, and
overall yields were calculated, while further detagging
followed in some cases.
The mixture of 8a-d coupled with 9 to afford a mixture
of four fluoro-tagged dimers 49a-d (Scheme 26). The
mixture of 49a-d was split into several portions. One
portion was extended to trimers 50a-d by a HWE
reaction. The final stage of OPV tetramer growth was a
Heck coupling with an endcapping styrene derivative 31.
The mixture of four tetramers was isolated by prepara-
tive HPLC. To prove that the correct intermediates were
generated in the mixture synthesis, a small amount of
49b was isolated from the mixture of 49a-d by prepara-
tive HPLC. Compound 49b was also synthesized sepa-
rately by Heck coupling of 8b and 9 under the same
conditions. These two products were identical by NMR
spectroscopic analysis.
The mixture of trimers 50a-d was split to two por-
tions. One portion was extended to tetramers with a nitro
terminus 51a-d (Scheme 26). The other portion coupled
with the carbomethoxy styrene derivative 30 to give a
tetramer mixture of 52a-d (Scheme 27).
Another portion of the dimer mixture 49a-d was
extended to dibutoxy-functionalized trimers 53a-d, which
were further extended to the tetramer mixture 54a-d
by coupling with p-nitrostyrene (Scheme 28).
HBF4 was used to cleave the tag and give the aryl
-
diazonium salt because the diazonium salts with a BF4
counterion are more stable than other forms. As shown
in Scheme 32, the tetramer with fluoro tag 51b was
treated with HBF4‚OMe2 complex. The diazonium func-
tionalized tetramer 62b was generated in 60% yield from
The third portion of 49a-d was subjected to a HWE
reaction with building block 21 (Scheme 29). The trimers
(75) Groenendaal, L.; Jonas, F.; Freitag, D.; Pielartzik, H.; Reynolds,
J. R. Adv. Mater. 2000, 12, 481-494.
J. Org. Chem, Vol. 70, No. 9, 2005 3403

Jian and Tour
TABLE 1. Building Blocks for OPV Library Synthesis
SCHEME 19
functionalized OPVs (54b and 54c) was red-shifted about
30 nm to 440 nm, compared to the OPV tetramers of
similar substitution.77 The absorption maximum of the
EDOT-containing hybrid oligomer 59d was further red-
shifted to 465 nm. This value is between that of the OPVs
and the alternating copolymers made using EDOT and
1,2-vinylene as repeat units.78
NMR Spectra of 1-Aryl-3,3-Dialkyltriazenes
Triazene [diazoamino group, R1-N1dN2-N3(R2R3)]
is the fundamental active group in a range of applica-
tions, from antitumor medicines79,80 to molecular elec-
tronics.81 The triazene moiety is a good chromophore,
with a deep color in solution and a low melting point. It
is known that the triazene group tends to adopt a trans
configuration about the N1dN2 double bond in the
ground state.82 However, the N1dN2 conformation is
highly dependent on the electronic and steric effects of
51b, and the fluorous tag 7b was recovered in 82% yield
from 51b. The overall yield of the diazonium salt 62b
was 30% for four steps (from 8b).
-
The diazonium salts, even in their BF4 form, decom-
posed slowly during storage at -20 °C. Thus, they were
generally stored in their protected triazene form, as
fluorous tagged tetramers. In-situ cleavage of a triazene
linkage and assembly of the resulting diazonium salt will
be performed on metallic or semiconducting surfaces.
This is under study in our laboratory, as is the screening
of the products.
Table 2 is a summary of OPV tetramers synthesized
by FMS and isolated by preparative HPLC.
UV-vis of the OPV Tetramers. The normalized
UV-vis absorption spectra of selected fluoro-tagged OPV
tetramers are shown in Figure 1. All of the fluoro-tagged
tetramers show broad and strong absorption in the visible
region.
(76) Schenk, R.; Gregorius H.; Meerholz, K.; Heinze, J.; Mu¨llen, K.
J. Am. Chem. Soc. 1991, 113, 2634-2647.
(77) Wang, S.; Oldham, W. J. Jr.; Hudack, R. A., Jr.; Bazan, G. C.
J. Am. Chem. Soc. 2000, 122, 5695-5709.
(78) Fu, Y.; Cheng, H.; Elsenbaumer, R. L. Chem. Mater. 1997, 9,
1720-1724.
(79) For a review about triazene in medicinal chemistry: Triazenes:
Chemical, Biological and Clinical Aspects; Giraldi, T., Connors, T. A.,
Carter, G., Eds.; Plenum: New York, 1990.
(80) Carvalho and co-workers have published a series concerning
triazene drug metabolites; Part 15: Carvalho, E.; Iley, J.; Perry, M. d.
J.; Rosa, E. Pharm. Res. 1998, 15, 931-935.
(81) Martin, P. J. In An Introduction to Molecular Electronics; Petty,
M. C., Bryce, M. R., Bloor, D., Eds.; Oxford University Press: New
York, 1995; Chapter 6.
(82) The conclusion is from: (a) Benson, F. R. The High Nitrogen
Compounds; John Wiley & Sons: New York, 1984; pp 49-50. Ex-
perimental support: (b) Kondrashev, Y. D. Kristallografiya 1961, 6,
515.
The diethyl functionalized OPVs (51b-d, 52c,d) show
absorption maximum at 401-408 nm. Compared to OPV
tetramers of similar substitution, the end groups (tria-
zene and nitro/carboxyl) red-shifted the absorption maxima
about 20 nm.76 The absorption maximum of dibutoxy
3404 J. Org. Chem., Vol. 70, No. 9, 2005

Synthesis of Diazonium-Functionalized Oligo(phenylenevinylene)s
SCHEME 20
SCHEME 21
SCHEME 22
SCHEME 23
the substituent groups.83 The reversible E/Z isomeriza-
tion can be thermally or photochemically induced, and
the interconversion process can be catalyzed by acid or
base and solvents can have effects on the relative rates
of interconversion.84,85 In addition to the possible N1d
N2 isomerism, rotation about the N2-N3 bond makes
the system more complicated. The rotational isomerism
about the N2-N3 bond has been observed experimen-
1
tally,86 and is supported by calculations.87 The H NMR
(84) Barra, M.; Chen, N. J. Org. Chem. 2000, 65, 5739-5744 And
references about N3 sp3 center inversion therein.
(85) Chen, N.; Barra, M.; Lee, I.; Chahal, N. J. Org. Chem. 2002,
67, 2271-2277.
(86) LaFrance, R. J.; Manning, H. W.; Vaughan, K. J. Org. Chem.
1985, 50, 2229-2232.
(83) Howell, J. M.; Kirschenbaum, L. J. J. Am. Chem. Soc. 1976,
98, 877-885.
J. Org. Chem, Vol. 70, No. 9, 2005 3405

Jian and Tour
SCHEME 24
SCHEME 25
and 13C NMR signal of substituents on N3 are usually
significantly broadened, evidence of restricted N2-N3
bond rotation. In earlier years, the origin of the rotational
barrier was ascribed to partial π-bond formation between
N2 and N3.88 Recent studies considered the isomerism
to originate from the inversion of the N3 sp3 center, since
the rotation around N2-N3 has a relatively high energy
barrier.84 In fact, both of these factors could contribute
to the rotational isomerism. Which energy barrier is
lower depends on the electronic and steric effect of the
substituents.
For aryl triazenes (Ar-N1dN2-N3<), the N1dN2 rota-
tion is further restricted due to conjugation of the
double bond with the aromatic ring.88 In these cases, at
room temperature, N2-N3 rotation is usually at a rate
that produces broad NMR signals for N3 substituents,
especially carbons and protons neighboring N3 (e.g.,
CH2* in Scheme 34). The cis and trans CH2* are usually
not differentiated, producing a broad peak in the 1H
NMR. The 13C NMR of C* gives rise to a broad and weak
signal that it is usually not observed at room tempera-
ture.
As a result of the isomerism, a triazene compound can
exist as a mixture of a number of rotamers. For each E/Z
isomer, there are several rotamers. Scheme 33 demon-
strates the triazene isomerization process and the major
rotamers, using 8a-d as an example. The stereodescrip-
tor E/Z is assigned to specify the N1dN2 space arrange-
ment, and cis/trans is used to specify N2-N3 space
arrangement.
Any molecular dynamic process is expected to be
temperature dependent. At low temperature, the rate of
bond rotation is decreased. When the N2-N3 rotation is
slow enough, the cis and trans C* can be differentiated.
Variable-temperature NMR studies of triazenes con-
firmed that distinct cis and trans C* signals can be
resolved at about 250 K, and fine coupling structures of
1H NMR signals appear at lower temperatures.88,89 The
electronic and steric effects of substituents on the aro-
(87) Pye, C. C.; Vaughan, K.; Glister, J. F. Can. J. Chem. 2002, 80,
447-454 and references about more calculation studies therein.
(88) Akhtar, M. H.; McDaniel, R. S.; Feser, M.; Oehlschlager, A. C.
Tetrahedron 1968, 24, 3389-3906.
(89) Hooper, D. L.; Pottie, I. R.; Vacheresse, M.; Vaughan, K. Can.
J. Chem. 1998, 76, 125-135.
3406 J. Org. Chem., Vol. 70, No. 9, 2005

Synthesis of Diazonium-Functionalized Oligo(phenylenevinylene)s
SCHEME 26
SCHEME 27
matic rings also influence the N2-N3 rotational isomer-
ism. The presence of a strong electron-withdrawing group
on the aromatic ring promotes the formation of 1,3-
dipolar compounds (Scheme 34, bottom left and right).
Under these circumstances, N2-N3 rotation is restricted
to the point where CH2* is either cis or trans to N1, and
(Figure 2b and 3b). An electron-withdrawing group
reduces the rate of N2-N3 rotation, and the ethyl groups
have to take a position either cis or trans to the aryl
group.
In aryl triazenes, the signals due to the aromatic
protons fall into two categories: (1) when the two N3
substituents are similar in size; (2) when one of the N3
substituents is much larger than the other. When the
two N3 substituents are similar in size, the signals due
to aromatic nuclei are all observed as usual. They exhibit
sharp, well-resolved peaks and expected coupling pat-
terns. More important is that the signals are not tem-
perature dependent. The magnetic field of the aromatic
ring changes little in different rotamers, and the aromatic
nuclei are usually not affected by triazene isomerization.
In compounds 35a-d, when both the N3 substituents are
ethyl groups, each aromatic carbon gives a sharp peak
in the 13C NMR spectrum. But when the two N3 substit-
uents are significantly different in size, rotation about
1
the signals due to CH2* (both H and 13C NMR) in the
cis and trans rotamers are distinct at room tempera-
ture.89 Figures 2 and 3 compare the N-ethyl resonance
of the two 1-aryl-3,3-diethyltriazene compounds 35b and
35d. When there is no electron-withdrawing group on the
aryl ring, the N-ethyl groups have a broad -CH3 1H NMR
signal (Figure 2a). The 13C signals of the N-ethyl groups
average out as very weak bumps (Figure 3a). With
enough scans in the FT-NMR analysis, two groups of
resonances could be observed, due to the moieties cis and
trans to the aryl group. When there is an electron-
withdrawing group, -CF3, in the aromatic ring, the two
ethyl groups are differentiated in both 1H and 13C NMR
J. Org. Chem, Vol. 70, No. 9, 2005 3407

Jian and Tour
SCHEME 28
SCHEME 29
the N2-N3 bond is restricted, giving two stereoisomers
that are distinguishable by NMR. This is the case for
compounds 8a-d. Under these conditions, a greater
number of aromatic signals are resolved, due to the
dynamic equilibrium of the rotamers.
When the two N3 substituents are significantly differ-
ent in size, not only are the protons and carbons on the
aromatic ring affected, the signals arising from aryl
substituents are also put in different magnetic fields in
different rotamers. From Scheme 33, we can see that
there are two positions for the ortho aryl substituent
R: cis and trans to the larger N3 substituents. These two
positions should give rise to two NMR signals for each
set of nuclei in R. However, in combination with its
electron effect, an electron donating R gives broad,
averaged 1H signals. And each carbon in electron donat-
1
ing R gives a single 13C signal (e.g., H and 13C NMR of
8a, R ) Et).
3408 J. Org. Chem., Vol. 70, No. 9, 2005

Synthesis of Diazonium-Functionalized Oligo(phenylenevinylene)s
SCHEME 30
SCHEME 31
SCHEME 32
If the substituent R contains fluorine atoms, the cis
and trans isomers can produce distinct signals in 19F
NMR spectra. Figure 4 compares the 19F NMR of two
Ar-F-type triazene compounds 35c and 8c. When the two
N3 substituents are both ethyl groups, the fluorine gives
a multiplet due to coupling with protons on the aromatic
ring (Figure 4a). When the two N3 substituents are
different in size, two multiplets are observed, indicating
an equilibrium between cis and trans isomers (Figure 4b).
Figure 5 compares the 19F NMR of two o-CF3 aryl
triazene compounds 35d and 8d. When the two N3
substituents are both ethyl groups, the CF3 group gives
J. Org. Chem, Vol. 70, No. 9, 2005 3409

Jian and Tour
TABLE 2. Isolated OPV Tetramers
a Overall yields for three steps from 8a-d, based on isolated products.
3410 J. Org. Chem., Vol. 70, No. 9, 2005

Synthesis of Diazonium-Functionalized Oligo(phenylenevinylene)s
FIGURE 1. UV-vis absorption spectra (normalized to peak height) of selected fluoro-tagged OPV tetramers (∼10-5 M solution
in CH2Cl2).
SCHEME 33
SCHEME 34
a sharp singlet (Figure 5a). When the two N3 substitu-
ents are different in size, two singlets are observed,
indicating an equilibrium between cis and trans isomers
(Figure 5b). From the 19F peak intensity of the two
isomers, the cis/trans ratio can be calculated.
Conclusions
We have outlined a method of synthesizing a library
of diazonium-functionalized OPV tetramers using FMS
technology. Alternating Heck coupling and HWE reac-
tion were used to grow OPVs and hybrid oligomers.
Model studies were used to optimize the reaction strate-
gies and OPVs and hybrid oligomers bearing aryl di-
azonium functionalities were synthesized. FMS tech-
nology successfully generated a library of OPVs and
hybrid oligomers and was superior to SPOS techniques.
Analytical HPLC was used to monitor the mixture
J. Org. Chem, Vol. 70, No. 9, 2005 3411

Jian and Tour
FIGURE 2. 1H NMR spectra of 1-aryl-3,3-diethyltriazene compounds in the N-ethyl resonance region (400 MHz, CDCl3): (a)
without any electron-withdrawing group on the aryl ring; (b) with an electron-withdrawing group on the aryl ring.
FIGURE 3. 13C NMR spectra of 1-aryl-3,3-diethyltriazene compounds in the N-ethyl resonance region (100 MHz, CDCl3): (a)
without any electron-withdrawing group on the aryl ring; (b) with an electron-withdrawing group on the aryl ring.
synthesis and final products were isolated by prepara-
tive HPLC. Although we did not synthesize all the
possible tetrameric OPVs and hybrid oliogmers in this
library, the efficiency of the approach was proven.
Provided with the appropriate building blocks, longer
OPVs or OPV-EDOT hybrid oligomers could be syn-
thesized using this method. Screening results of the
OPV and hybrid oligomer products in molecular elec-
tronic and optoelectronic applications will be reported in
due course.
3412 J. Org. Chem., Vol. 70, No. 9, 2005

Synthesis of Diazonium-Functionalized Oligo(phenylenevinylene)s
FIGURE 4. 19F NMR of Ar-F triazene compounds (470.5 MHz, CDCl3): (a) 19F NMR of 35c; (b) 19F NMR of 8c.
FIGURE 5. 19F NMR of Ar-CF3 triazene compounds (470.5 MHz, CDCl3): (a) 19F NMR of 35d; (b) 19F NMR of 8d.
MHz) δ 7.37 (d, J ) 2.1 Hz, 1H), 7.32 (dd, J ) 2.1, 8.3 Hz,
1H), 6.47 (d, J ) 8.3 Hz, 1H), 3.64 (br, 2H), 2.47 (q, J ) 7.5
Hz, 2H), 1.25 (t, J ) 7.5 Hz, 3H); 13C NMR (CDCl3, 100 MHz)
δ 144.2, 137.1, 135.8, 131.1, 117.8, 80.4, 24.1, 13.1; LRMS for
C8H10IN (EI) m/z (peak intensity, assignment) 247 (100, M+),
232 (90, M+ - CH3); HRMS calcd for C8H10IN 246.9858, found
246.9851.
2-Ethyl-4-iodobenzenediazonium Tetrafluoroborate
(2a). According to the general procedure for the diazotization
of anilines, 1a (13.15 g, 53.22 mmol), BF3‚OEt2 (27.0 mL, 213
mmol), t-BuONO (22.3 mL, 186 mmol), THF (50 mL), and
ether (300 mL) gave 2a as a white solid (15.4 g, 84%): mp >
91 °C dec; IR (KBr) 3009 (m), 2973 (m), 2274 (s), 2244 (s), 1056
Experimental Section
2-Ethyl-4-iodoaniline (1a).50 To the solution of 2-ethyl-
aniline (42.81 g, 353.3 mmol) in MeOH (200 mL), cooled in an
ice bath, was added a solution of NaHCO3 (47.48 g, 565.2
mmol)/H2O (200 mL). I2 (89.67 g, 353.3 mmol) was then added
portionwise over 30 min. The reaction mixture was stirred at
room temperature for 2 h, poured into water in a separatory
funnel, and extracted with EtOAc. The organic layer was
washed with Na2SO3 (satd aq) twice, H2O twice, and brine once
and dried over MgSO4, and the solvent was removed in vacuo.
The residue was passed through a plug of silica gel to give 1a
(82.82 g, 95%) as dark unstable liquid: IR (KBr, neat) 3469
(br), 3381 (m), 2964 (s), 2871 (s) cm-1; H NMR (CDCl3, 400
1
J. Org. Chem, Vol. 70, No. 9, 2005 3413

Jian and Tour
(s, br), 822 (m) cm-1; 1H NMR (CD3CN, 400 MHz) δ 8.26 (d, J
) 1.4 Hz, 1H), 8.14 (dd, J ) 8.7, 1.5 Hz, 1H), 8.07 (d, J ) 8.7
(t, J ) 7.1 Hz, 3H); 19F NMR (CDCl3, 470 MHz) δ -81.6 (m,
3F), -111.8 (m, 2F), -124.7 (m, 2F), -126.3 (m, 2F); LRMS
for C21H24F9NO2 (EI) m/z (peak intensity, assignment): 437
(20, M+ - C4H8), 335 (100, M+ - Boc - n-PrN), 57 (35, t-Bu+).
Hz, 1H), 2.95 (q, J ) 7.5 Hz, 2H), 1.34 (t, J ) 7.5 Hz, 3H); 13
C
NMR (CD3CN, 100 MHz) δ 151.2, 142.3, 140.3, 133.6, 115.0,
+
114.6, 26.3, 13.8; FAB HRMS calcd for C8H8IN2 258.9732,
5b. According to the general coupling procedure A, 4 (1.413
g, 4.305 mmol), 1H,1H,2H-perfluoro-1-octene (1.0 mL, 4.7
mmol), Pd(OAc)2 (0.0146 g, 0.0650 mmol), NaHCO3 (0.904 g,
10.7 mmol), n-Bu4NHSO4 (1.46 g, 4.30 mmol), and DMF (20
mL) gave 5b (1.69 g, 66%) as a slightly yellow oil: IR (KBr,
neat) 2972 (s), 1691 (s), 1300-1064 (s) cm-1; 1H NMR (CDCl3,
400 MHz) δ 7.45 (d, J ) 8.1 Hz, 2H), 7.28 (br, 2H), 7.18 (dm,
J ) 16.1 Hz, 1H), 6.20 (m, 1H), 4.47 (s, 2H), 3.22 and 3.13 (2
s, 2H), 1.47 (m, 11H), 0.88 (t, J ) 7.1 Hz, 3H); 19F NMR (CDCl3,
470 MHz) δ -81.3 (t, 3F), -111.5 (m, 2F), -122.1 (m, 2F),
-123.4 (m, 2F), -123.7 (m, 2F), -126.7 (m, 2F); HRMS (CI)
calcd for C23H25F13NO2 (M + H) 594.1678, found 594.1596;
LRMS for C23H24F13NO2 (EI) m/z (peak intensity, assignment)
537 (16, M+ - C4H8), 435 (100, M+ - Boc - n-PrN), 57 (5,
t-Bu+).
found 258.8633.
2-Fluoro-4-iodobenzenediazonium Tetrafluoroborate
(2c). According to the general procedure for the diazotization
of anilines, 1c (5.663 g, 23.89 mmol), BF3‚OEt2 (12.1 mL, 95.6
mmol), t-BuONO (10.0 mL, 83.6 mmol), THF (50 mL), and
ether (150 mL) gave 2c as a white pale solid (7.86 g, 98%):
mp > 150 °C dec; IR (KBr) 3104 (m), 2270 (s), 1051 (s, br),
827 (m) cm-1; 1H NMR (CD3CN, 500 MHz) δ 8.26 (m, 1H), 8.16
(m, 2H); 13C NMR (CD3CN, 125 MHz) δ 161.8, 159.6, 138.8 (d,
JC-F ) 3.3 Hz), 133.6 (d, JC-F ) 3.9 Hz), 130.1 (d, JC-F ) 17.1
+
Hz), 117.4 (d, JC-F ) 8.5 Hz); FAB HRMS calcd for C6H3FIN2
248.9325, found 248.8257.
N-(4-Bromobenzyl)propan-1-amine (3).91 A flask charged
with n-propylamine (250 mL) was cooled in an ice bath.
4-Bromobenzyl bromide (9.93 g, 39.7 mmol) was divided into
four portions. One portion was dissolved in a minimum amount
of THF (3 mL). The solution was added dropwise to the
n-propylamine while stirring. The reaction mixture was then
stirred at room temperature for 1 h. n-Propylamine was then
recovered by distillation, and reused to react with another
portion of 4-bromobenzyl bromide. This was done four times.
The residues of the distillations were then combined, diluted
with EtOAc, and poured into water in a separatory funnel.
The organic layer was washed with H2O three times and brine
once, dried over MgSO4, and filtered, and the solvent was
removed in vacuo. The residue was passed through a plug of
silica gel to afford 3 as slightly yellow liquid (9.06 g, 100%):
Rf ) 0.19 (hexanes/EtOAc ) 1/1); 1H NMR (CDCl3, 400 MHz)
δ 7.45 (d, J ) 8.4 Hz, 2H), 7.22 (d, J ) 8.5 Hz, 2H), 3.76 (s,
2H), 2.59 (t, J ) 7.3 Hz, 2H), 1.53 (sext, J ) 7.3 Hz, 2H), 1.26
(br, 1H), 0.94 (t, J ) 7.4 Hz, 3H); 13C NMR (CDCl3, 100 MHz)
δ 140.1, 131.8, 130.2, 121.0, 53.7, 51.7, 23.6, 12.2.
5c. According to the general coupling procedure B, 4 (1.129
g, 3.439 mmol), 1H,1H,2H-perfluoro-1-docene (1.0 mL, 3.8
mmol), palladacycle (0.032 g, 0.034 mmol), NaOAc (0.367 g,
4.47 mmol), and DMF (20 mL) gave 5c (1.8 g, 77%) as a slightly
yellow oil, which solidified slowly at room temperature: mp
57-58 °C; IR (KBr) 3044 (m), 2975 (s), 1688 (s), 1251-1050
(s) cm-1 1H NMR (CDCl3, 400 MHz) δ 7.45 (d, J ) 8.1 Hz,
;
2H), 7.28 (br, 2H), 7.17 (dm, J ) 16.1 Hz, 1H), 6.20 (m, 1H),
4.47 (s, 2H), 3.21 and 3.12 (2 br, 2H), 1.47 (m, 11H), 0.87 (t, J
) 7.1 Hz, 3H); 19F NMR (CDCl3, 470 MHz) δ -81.7 (t, J )
10.1 Hz, 3F), -111.8 (m, 2F), -122.1 (m, 2F), -122.7 (m, 4F),
-123.5 (m, 2F), -123.9 (m, 2F), -126.9 (m, 2F); HRMS
calcd for C25H24F17NO2 693.1536, found 693.1537; LRMS for
C25H24F17NO2 (EI) m/z (peak intensity, assignment) 637 (10,
M+ - C4H8), 535 (100, M+ - Boc - n-PrN), 57 (15, t-Bu+).
5d. According to the general coupling procedure B, 4 (1.476
g, 4.497 mmol), 1H,1H,2H-perfluoro1-dodecene (2.72 g, 4.98
mmol), palladacycle (0.042 g, 0.045 mmol), NaOAc (0.480 g,
5.85 mmol), and DMF (25 mL) gave 5d (2.5 g, 70%) as a white
solid: mp 71-72 °C; IR (KBr) 2983 (s), 1689 (s), 1305-1152
tert-Butyl 4-Bromobenzylpropylcarbamate (4). To the
solution of 3 (9.06 g, 39.7 mmol) in CH2Cl2 (80 mL), cooled to
0 °C, was added via syringe a solution of Boc2O (10.71 g, 47.61
mmol) in CH2Cl2 (20 mL), followed by NEt3 (6.7 mL, 48 mmol).
The reaction mixture was then stirred in room temperature
for 4.5 h and concentrated in vacuo. The residue was parti-
tioned between EtOAc and water in a separatory funnel. The
organic layer was then washed with H2O three times and brine
twice, dried over MgSO4, and filtered, and the solvent was
removed in vacuo. The residue was purified by column chro-
matography to afford 4 as a clear liquid (13.0 g, 100%): Rf )
0.32 (hexanes/CH2Cl2 ) 1/1); IR (KBr, neat) 2969(s), 1682 (s),
795 (m) cm-1; 1H NMR (CDCl3, 400 MHz) δ 7.40 (d-br, J ) 8.1
Hz, 2H), 7.09 (br, 2H), 4.35 (s, 2H), 3.14 and 3.07 (2 s, br, 2H),
1.44 (m, 11H), 0.82 (t, J ) 7.2 Hz, 3H); 13C NMR (CDCl3, 100
MHz, at room temperature, some Cs are multiplets because
of amide isomerization) δ 156.3 (m), 138.2 (m), 131.9, 129.4
(2m), 121.2, 80.0, 50.0 (2m), 48.8 (m), 28.6, 21.7 (m), 11.7;
HRMS calcd for C15H23BrNO2 328.0912, found 328.0901;
LRMS for C15H23BrNO2 (EI) m/z (peak intensity, assignment)
271 (77, M+ - t-Bu), 273 (77, M+ - t-Bu), 169 (100, BrC7H6+),
171 (100, BrC7H6+), 57 (73, t-Bu+).
(s) cm-1 1H NMR (CDCl3, 400 MHz) δ 7.45 (d, J ) 8.1 Hz,
;
2H), 7.28 (br, 2H), 7.18 (dm, J ) 16.1 Hz, 1H), 6.20 (m, 1H),
4.47 (s, 2H), 3.21 and 3.12 (2 br, 2H), 1.47 (m, 11H), 0.87 (t, J
) 7.1 Hz, 3H); 19F NMR (CDCl3, 470 MHz) δ -81.3 (t, J ) 9.6
Hz, 3F), -111.5 (m, 2F), -122.9 (m, 2F), -122.3 (m, 8F),
-123.2 (m, 2F), -123.7 (m, 2F), -126.6 (m, 2F); LRMS for
C27H24F21NO2 (EI) m/z (peak intensity, assignment) 635 (100,
M+ - Boc - n-PrN), 57 (10, t-Bu+).
6a. According to the general procedure for hydrogenation,
5a (5.99 g, 12.1 mmol), Pd (10% on charcoal, 1.55 g), and
EtOAc (80 mL) gave 6a (5.56 g, 93%) as a clear oil: IR (KBr)
1
2971 (s), 1697 (s), 1305-1088 (s) cm-1; H NMR (CDCl3, 400
MHz) δ 7.18 (m, 4H), 4.43 (s, 2H), 3.18 and 3.11 (2 br, 2H),
2.94-2.88 (m, 2H), 2.45-2.31 (m, 2H), 1.48 (m, 11H), 0.87 (t,
J ) 7.3 Hz, 3H); 13C NMR (CDCl3, 100 MHz, some Cs are
missing or multiplets because of isomerization of carbamate)
δ 138.3, 128.5, 80.0, 50.0 (m), 48.8, 33.3 (t, JC-F ) 22.1 Hz),
26.52 (t, JC-F ) 4.0 Hz), 21.6 (m), 11.7; 19F NMR (CDCl3, 470
MHz) δ -81.6 (t, J ) 8.9 Hz, 3F), -115.4 (m, 2F), -125.0
(m, 2F), -126.6 (m, 2F); HRMS (CI) calcd for C21H27F9NO2
(M + H) 496.1898, found 496.1785; HRMS (EI) calcd for
C21H26F9NO2 495.1820, found 495.1820.
5a. According to the general coupling procedure B, 4 (3.116
g, 9.463 mmol), 1H,1H,2H-perfluoro-1-hexene (2.0 mL, 12
mmol), palladacycle (0.178 g, 0.190 mmol), NaOAc (1.012 g,
12.34 mmol), and DMF (25 mL) gave 5a (4.26 g, 91%) as a
slightly yellow oil: IR (KBr, neat) 2971 (s), 1693 (s), 1235-
6b. According to the general procedure for hydrogenation,
5b (1.69 g, 2.85 mmol), Pd (10% on charcoal, 0.364 g), and
EtOAc (15 mL) gave 6b (1.58 g, 93%) as a clear oil: IR (KBr):
1
1133 (s) cm-1; H NMR (CDCl3, 400 MHz) δ 7.45 (d, J ) 8.1
Hz, 2H), 7.28 (br, 2H), 7.18 (dm, J ) 16.1 Hz, 1H), 6.20 (m,
1
2971 (s), 1694 (s), 1367-1088 (s) cm-1; H NMR (CDCl3, 400
1H), 4.47 (s, 2H), 3.22 and 3.12 (2 s, 2H), 1.47 (m, 11H), 0.87
MHz) δ 7.19 (m, 4H), 4.43 (s, 2H), 3.17 and 3.12 (2 br, 2H),
2.94 and 2.90 (m, 2H), 2.45-2.33 (m, 2H), 1.50 (m, 11H), 0.87
(t, J ) 7.3 Hz, 3H); 19F NMR (CDCl3, 470 MHz) δ -81.5 (m,
3F), -115.3 (m, 2F), -122.5 (m, 2F), -123.5 (m, 2F), -124.1
(m, 2F), -126.8 (m, 2F); HRMS calcd for C23H26F13NO2
595.1756, found 595.1749; LRMS (EI) m/z (peak intensity,
(90) FluoroFlash HPLC columns were purchased from Fluorous
Technologies, Inc., Pittsburgh, PA
(91) Kerdesky, F. A. J.; Haight, A.; Narayanan, B. A.; Nordeen, C.
W.; Scarpetti, D.; Seif, L. S.; Wittenberger, S.; Morton, H. E. Synth.
Commun. 1993, 23, 2027-2039.
3414 J. Org. Chem., Vol. 70, No. 9, 2005

Synthesis of Diazonium-Functionalized Oligo(phenylenevinylene)s
assignment) 595 (1, M+), 437 (100, M+ - Boc - C3H7N), 57
(15, t-Bu+).
7d. According to the general procedure for amine deprotec-
tion, 6d (0.964 g, 1.21 mmol), TFA (3 mL), and CH2Cl2 (30
mL) gave 7d (0.784 g, 93%) as a white solid: mp 60-61 °C;
6c. According to the general procedure for hydrogenation,
5c (4.01 g, 5.78 mmol), Pd (10% on charcoal, 0.738 g), and
EtOAc (50 mL) gave 6c (3.83 g, 95%) as a clear oil: IR
1
IR (KBr) 3340 (br), 2963 (m), 1210-1150 (s) cm-1; H NMR
(CDCl3, 400 MHz) δ 7.32 (d, J ) 7.9 Hz, 2H), 7.19 (d, J ) 7.9
Hz, 2H), 3.80 (s, 2H), 2.94-2.90 (m, 2H), 2.64 (t, J ) 7.5 Hz,
2H), 2.45-2.32 (m, 2H), 1.57 (sext, J ) 7.5 Hz, 2H), 1.39 (br,
1H), 0.96 (t, J ) 7.4 Hz, 3H); 13C NMR (CDCl3, 100 MHz; the
signals due to perfluoro carbons were not picked because of
strong C-F coupling and overlap) δ 139.7, 138.2, 129.0, 128.7,
54.1, 51.9, 33.5 (t, JC-F ) 21.9 Hz), 26.5 (t, JC-F ) 4.3 Hz),
23.7, 12.0; 19F NMR (CDCl3, 470 MHz) δ -81.4 (t, J ) 10.1
Hz, 3F), -115.2 (m, 2F), -122.2 (m, 10F), -123.2 (m, 2F),
-124.0 (m, 2F), -126.7 (m, 2F); HRMS calcd for C24H21F13IN3
725.0573, found 725.0582.
8a. According to the general procedure for triazene forma-
tion, 2a (4.53 g, 13.1 mmol), 7a (4.31 g, 10.9 mmol), K2CO3
(3.05 g, 22.1 mmol), and CH3CN (100 mL) gave 8a (5.19 g,
73%) as an orange oil: Rf ) 0.43 (hexanes/CH2Cl2 ) 8/1); IR
(KBr) 2966 (s), 1455-1097 (s) cm-1; 1H NMR (CDCl3, 400 MHz)
δ 7.54 (m, 1H), 7.49 (dd, J ) 8.4 Hz, 1.8 Hz, 1H), 7.27-7.19
(m, 5H), 4.94 (s, 2H), 3.74 (br, 1H), 2.97-2.91 (m, 2H), 2.72
(br, 2H), 2.47-2.32 (m, 2H), 1.73 (br, 2H), 1.12 (br, 3H), 0.95
(br-m, 3H); 13C NMR (CDCl3, 100 MHz; two aromatic C’s not
observed because of triazene rotamer interconversion; the
signals due to perfluoro carbons were not picked because of
strong C-F coupling and overlap) δ 148.2, 141.8, 138.4, 135.7,
129.0, 128.6, 119.1, 90.5, 33.3 (t, JC-F ) 21.9 Hz), 32.1, 26.5
(t, JC-F ) 4.3 Hz), 25.0, 23.1, 15.6, 14.6, 11.9; 19F NMR (CDCl3,
470 MHz) δ -80.2 (m, 3F), -114.0 (m, 2F), -123.7 (m, 2F),
-125.2 (m, 2F); HRMS calcd for C24H25IN3F9 653.0949, found
653.0941.
1
(KBr, neat) 2972 (m), 1692 (s), 1243-1146 (s) cm-1; H NMR
(CDCl3, 400 MHz) δ 7.20 (m, 4H), 4.45 (s, 2H), 3.19 and 3.12
(2 br, 2H), 2.95-2.90 (m, 2H), 2.44-2.34 (m, 2H), 1.49 (m,
11H), 0.87 (t, J ) 7.3 Hz, 3H); 19F NMR (CDCl3, 470 MHz) δ
-81.65 (t, J ) 9.4 Hz, 3F), -115.4 (m, 2F), -122.4 (m, 2F),
-122.7 (m, 4F), -123.5 (m, 2F), -124.2 (m, 2F), -126.9 (m,
2F); LRMS for C25H26F17NO2 (EI) m/z (peak intensity, assign-
ment) 695 (5, M+), 594 (15, M+ - Boc), 537 (100, M+ - Boc -
NHC3H7).
6d. According to the general procedure for hydrogenation,
5d (5.219 g, 6.577 mmol), Pd (10% on charcoal, 0.840 g), and
EtOAc (60 mL) gave 6d (5.07 g, 97%) as a clear oil, which
solidified slowly at room temperature to give a white solid:
mp 66-67 °C; IR (KBr) 2972 (m), 1688 (s), 1244-1149 (s), 882
1
(s) cm-1; H NMR (CDCl3, 400 MHz) δ 7.18 (m, 4H), 4.43 (s,
2H), 3.18 and 3.11 (2 br, 2H), 2.94-2.89 (m, 2H), 2.45-2.33
(m, 2H), 1.48 (m, 11H), 0.87 (t, J ) 7.3 Hz, 3H); 19F NMR
(CDCl3, 470 MHz) δ -81.4 (t, J ) 10.1 Hz, 3F), -115.2 (m,
2F), -122.4 (m, 10F), -123.3 (m, 2F), -124.1 (m, 2F), -126.8
(m, 2F); HRMS calcd for C27H26F21NO2 795.1628, found
795.1613.
7a. According to the general procedure for amine deprotec-
tion, 6a (5.56 g, 11.2 mmol), TFA (5 mL), and CH2Cl2 (50 mL)
gave 7a (4.31 g, 97%) as a slightly yellow oil: IR (KBr) 3305
(br), 2961 (m), 1357-1134 (s) cm-1; 1H NMR (CDCl3, 400 MHz)
δ 7.31 (d, J ) 7.9 Hz, 2H), 7.19 (d, J ) 8.0 Hz, 2H), 3.80 (s,
2H), 2.96-2.91 (m, 2H), 2.63 (t, J ) 7.5 Hz, 2H), 2.48-2.32
(m, 2H), 1.56 (sext, J ) 7.5 Hz, 2H), 1.45 (br, 1H), 0.96 (t, J )
7.4 Hz, 3H); 13C NMR (CDCl3, 100 MHz; the signals due to
perfluoro carbons were not picked because of strong C-F
coupling and overlap) δ 139.6, 138.1, 129.0, 128.7, 54.1, 51.8,
8b. According to the general procedure for triazene forma-
tion, 2b (0.931 g, 2.93 mmol), 7b (1.21 g, 2.44 mmol), K2CO3
(0.674 g, 4.88 mmol), and CH3CN (50 mL) gave 8b (1.77 g,
100%) as an orange oil: Rf ) 0.49 (hexanes/CH2Cl2 ) 4/1); IR
(KBr) 2966 (m), 1239-1120 (s) cm-1 1H NMR (CDCl3, 400
;
33.4 (t, JC-F ) 21.9 Hz), 26.5 (t, JC-F ) 4.3 Hz), 23.6, 12.1; 19
F
MHz) δ 7.68 (d, J ) 8.7 Hz, 2H), 7.28-7.20 (m, 6H), 4.97 (s,
2H), 3.68 (br-s, 2H), 2.97-2.93 (m, 2H), 2.49-2.32 (m, 2H),
1.72 (br-s, 2H), 0.95 (t, J ) 7.2 Hz, 3H); 13C NMR (CDCl3, 100
MHz; one aromatic C not observed because of triazene rotamer
interconversion; the signals due to perfluoro carbons were not
picked because of strong C-F coupling and overlap) δ 151.0,
138.3, 129.0, 128.9, 123.2, 123.2, 90.0, 33.4 (t, JC-F ) 22.0 Hz),
32.1, 26.6 (t, JC-F ) 4.1 Hz), 23.2, 14.6, 11.9; 19F NMR (CDCl3,
470 MHz) δ -80.1 (m, 3F), -113.9 (m, 2F), -121.2 (m, 2F),
-122.1 (m, 2F), -122.8 (m, 2F), -125.4 (m, 2F); HRMS calcd
for C24H21F13IN3 725.0573, found 725.0574.
NMR (CDCl3, 470 MHz) δ -81.8 (m, 3F), -115.5 (m, 2F),
-125.1 (m, 2F), -126.7 (m, 2F); HRMS calcd for C16H18NF9
395.1295, found 395.1292.
7b. According to the general procedure for amine deprotec-
tion, 6b (4.18 g, 7.02 mmol), TFA (5 mL) and CH2Cl2 (50 mL)
gave 7b (3.41 g, 98%) as a slightly yellow oil: IR (KBr) 3303
(br), 2961 (m), 1366-1118 (s) cm-1; 1H NMR (CDCl3, 400 MHz)
δ 7.31 (d, J ) 8.0 Hz, 2H), 7.19 (d, J ) 8.0 Hz, 2H), 3.80 (s,
2H), 2.96-2.91 (m, 2H), 2.63 (t, J ) 7.5 Hz, 2H), 2.45-2.34
(m, 2H), 1.56 (sext + br, J ) 7.5 Hz, 2H+1H), 0.95 (t, J ) 7.4
Hz, 3H); 13C NMR (CDCl3, 100 MHz; the signals due to
perfluoro carbons were not picked because of strong C-F
coupling and overlap) δ 139.6, 138.2, 129.0, 128.8, 54.1, 51.8,
8c. According to the general procedure for triazene forma-
tion, 2c (1.74 g, 5.17 mmol), 7c (2.37 g, 3.98 mmol), K2CO3
(1.10 g, 7.96 mmol), and CH3CN (50 mL), together with THF
(50 mL) gave 8c (2.82 g, 84%) as a pinkish solid: Rf ) 0.33
(hexanes/CH2Cl2 ) 8/1); mp 62-63 °C; IR (KBr) 2971 (m),
33.5 (t, JC-F ) 22.0 Hz), 26.6 (t, JC-F ) 4.2 Hz), 23.6, 12.2; 19
F
NMR (CDCl3, 470 MHz) δ -81.6 (t, J ) 10.1 Hz, 3F), -115.3
(m, 2F), -122.5 (m, 2F), -123.5 (m, 2F), -124.2 (m, 2F),
-126.8 (m, 2F); HRMS calcd for C18H18F13N 495.1232, found
495.1225.
1
1290-1100 (s) cm-1; H NMR (CDCl3, 400 MHz) δ 7.49-7.43
(m, 2H), 7.35-7.15 (m, 5H), 5.00 (br-s, 2H), 3.76 and 3.68 (2
s, 2H), 2.95 (m, 2H), 2.49-2.30 (m, 2H), 1.78 and 1.70 (2 br-s,
2H), 0.97 (m, 3H); 13C NMR is complicated because of triazene
rotamer interconversion and overlap of perfluoro carbons with
aromatic carbons; 19F NMR (CDCl3, 470 MHz) δ -81.7 (t, J )
9.9 Hz, 3F), -115.3 (m, 2F), -122.4 (m, 2F), -122.6 (m, 4F),
-123.5 (m, 2F), -124.1 (m, 2H), -125.5 (2m, because of NdN
E/Z interconversion, 1F, Ph-F), -126.9 (m, 2F); HRMS calcd
for C26H20IN3F18 843.0414, found 843.0446.
7c. According to the general procedure for amine deprotec-
tion, 6c (1.69 g, 2.43 mmol), TFA (3 mL), and CH2Cl2 (30 mL)
gave 7c (1.44 g, 100%) as a slightly yellow oil at room
temperature, which solidified upon refrigeration: IR (KBr)
3306 (br), 2961 (m), 1330-1115 (s) cm-1; 1H NMR (CDCl3, 400
MHz) δ 7.31 (d, J ) 8.1 Hz, 2H), 7.19 (d, J ) 8.1 Hz, 2H), 3.80
(s, 2H), 2.94-2.90 (m, 2H), 2.63 (t, J ) 7.5 Hz, 2H), 2.48-2.32
(m, 2H), 1.56 (sext, J ) 7.5 Hz, 2H), 1.46 (br, 1H), 0.95 (t, J )
7.4 Hz, 3H); 13C NMR (CDCl3, 100 MHz; the signals due to
perfluoro carbons were not picked because of strong C-F
coupling and overlap) δ 139.6, 138.2, 129.0, 128.8, 54.1, 51.9,
8d. According to the general procedure for triazene forma-
tion, 2d (0.347 g, 0.899 mmol), 7d (0.521 g, 0.749 mmol),
K2CO3 (0.207 g, 1.50 mmol), and CH3CN (30 mL), together
with THF (30 mL), gave 8d (0.74 g, 99%) as a yellow solid: Rf
) 0.56 (hexanes/CH2Cl2 ) 6/1); mp 75-76 °C; IR (KBr) 2960
33.5 (t, JC-F ) 21.9 Hz), 26.6 (t, JC-F ) 4.3 Hz), 23.7, 12.2; 19
F
NMR (CDCl3, 470 MHz) δ -81.8 (t, J ) 9.4 Hz, 3F), -115.4
(m, 2F), -122.5 (m, 2F), -122.7 (m, 4F), -123.5 (m, 2F),
-124.2 (m, 2F), -127.0 (m, 2F); LRMS for C20H18F17N (EI) m/z
(peak intensity, assignment) 595 (55, M+), 566 (90, M+ - C2H5),
537 (100, M+ - NHC3H7).
(m), 1350-1080 (s) cm-1 1H NMR (CDCl3, 400 MHz) δ7.95
;
(d, J ) 8.2 Hz, 1H), 7.87 (pseudo-t, J ) 7.4 Hz, 1H), 7.42 (2d,
J ) 8.6 Hz, 1H), 7.27-7.16 (m, 4H), 5.02 and 4.95 (2 s, 2H),
3.75 and 3.61 (2t, J ) 7.3 Hz, 2H), 2.99-2.88 (m, 2H), 2.47-
J. Org. Chem, Vol. 70, No. 9, 2005 3415

Jian and Tour
2.30 (m, 2H), 1.78 and 1.62 (2 sext, J ) 7.4 Hz, 2H), 0.97 and
0.89 (2t, J ) 7.4 Hz, 3H); 13C NMR (CDCl3, 100 MHz, the
signals due to perfluoro carbons were not picked because of
strong C-F coupling and overlap) δ 148.8, 141.6, 139.5 and
138.8 (2 s, cis and trans), 135.5 (q, J ) 5.1 Hz), 134.9, 129.2
and 129.2 (2 s, cis and trans), 128.9 and128.8 (2 s, cis and
trans), 120.1 and 119.7 (2 s, cis and trans), 88.2, 59.1 and 56.5
(2 s, cis and trans), 50.2 and 49.4 (2 s, cis and trans), 33.4 (t,
JC-F ) 22.9 Hz), 26.6 (m), 22.5 and 19.3 (2 s, cis and trans),
11.9 and11.7 (2 s, cis and trans); 19F NMR (CDCl3, 470 MHz)
δ -60.6 and -60.8 (2 s, 3F, Ar-CF3), -81.4 (t, J ) 10.1 Hz,
3F), -115.1 (m, 2F), -122.4 (m, 10F), -123.2 (m, 2F), -124.0
(m, 2F), -126.7 (m, 2F); HRMS calcd for C29H20F24IN3 993.0319,
found 993.0317.
2,5-Diethyl-4-iodobenzaldehyde (11). In an oven-dried
three-neck flask were charged 1056 (6.46 g, 16.73 mmol) and
THF (100 mL). The solution was cooled to -78 °C to form a
white slurry. To this mixture was added dropwise n-BuLi (2.03
M in hexane, 8.47 mL) over 20 min. The mixture was then
stirred at -78 °C for 4 h. DMF (anhydrous, 3.9 mL, 50 mmol)
was added in one portion. The reaction temperature was
allowed to increase to room temperature over 6 h and then
poured into water and partitioned. The aqueous layer was
extracted with CH2Cl2 twice. The organic layers were com-
bined, dried over MgSO4, and filtered, and solvent was
removed in vacuo. The residue was purified by column chro-
matography to afford 11 as a clear oil (2.49 g, 52%; a yield as
high as 57% was obtained) at room temperature, which
product crystallized as a yellow solid and was collected by
filtration, washed with hexanes twice, and dried in air to give
15 (5.96 g, 85%) as a yellow crystalline solid: mp 73.5-74.5
°C; IR (KBr) 2956 (m), 2866 (m), 1669 (s), 1210 (s), 1036 (m)
cm-1; 1H NMR (CDCl3, 400 MHz) δ 10.44 (s, 1H), 7.47 (s, 1H),
7.20 (s, 1H), 4.04 (t, J ) 6.4 Hz, 2H), 4.02 (t, J ) 6.4 Hz, 2H),
1.82 (m, 4H), 1.53 (m, 4H), 1.02 (t, J ) 7.4 Hz, 3H), 0.99 (t, J
) 7.4 Hz, 3H); 13C NMR (CDCl3, 100 MHz) δ 189.5, 156.1,
152.5, 125.5, 124.9, 109.1, 97.1, 69.9, 69.5, 31.53, 31.51, 19.7,
19.6, 14.23, 14.19; HRMS calcd for C15H21IO3 376.0535, found
376.0536.
2,5-Dibutoxy-4-vinylbenzaldehyde (16). An oven-dried
screw-cap tube was charged with 15 (0.890 g, 3.61 mmol),
Pd(dba)2 (0.027 g, 0.047 mmol), CuI (0.018 g, 0.094 mmol),
PPh3 (0.049 g, 0.19 mmol). and BHT (one crystal). The tube
was septum-capped, evacuated and back-filled with N2 three
times. A solution of vinyltributyltin (0.900 g, 2.84 mmol) in
THF (15 mL) was transferred to the tube via cannula. The
tube was then capped with its screw cap, and the solution was
stirred in an oil bath at 80 °C for 19 h. The reaction mixture
was then cooled to room temperature and poured into H2O in
a separatory funnel, and the aqueous layer was extracted with
EtOAc. The organic layer was washed with H2O twice and
brine twice, dried over MgSO4, and filtered, and the solvent
was removed in vacuo. The residue was purified by column
chromatography and then recrystallized from MeOH to afford
16 (0.57 g, 87%) as yellow fluorescent crystals: Rf ) 0.44
(hexanes/CH2Cl2 ) 1/1); mp 47-48 °C; IR (KBr) 2953 (m), 1665
(s), 1210 (s) cm-1; 1H NMR (CDCl3, 400 MHz) δ 10.45 (s, 1H),
7.30 (s, 1H), 7.11-7.04 (s+dd, J ) 11.1 Hz, 17.7 Hz, 2H), 5.87
(dd, J ) 17.8 Hz, 0.9 Hz, 1H), 5.43 (dd, J ) 11.1 Hz, 0.9 Hz,
1H), 4.08 (t, J ) 6.4 Hz, 2H), 4.00 (t, J ) 6.4 Hz, 2H), 1.82 (2
quint, J ) 6.5 Hz, 4H), 1.52 (m, 4H), 1.00 (2t, J ) 7.3 Hz, 6H);
13C NMR (CDCl3, 100 MHz) δ 189.7, 156.6, 150.9, 134.8, 131.8,
124.9, 118.0, 111.2, 110.4, 69.3, 69.1, 31.75, 31.73, 19.8, 19.7,
14.31, 14.28; HRMS calcd for C17H24O3 276.1725, found
276.1727.
7-Bromo-2,3-dihydrothieno[3,4-b][1,4]dioxine-5-car-
baldehyde (18). To the mixture of 1761 (0.208 g, 1.22 mmol),
AcOH (10 mL), and THF (10 mL), cooled in an ice bath, was
portionwise added NBS (0.228 g, 1.28 mmol). The reaction
mixture was stirred at room temperature for 17 h, poured into
H2O in a separatory funnel, and extracted with EtOAc. The
organic layer was washed with H2O three times, Na2CO3 (satd
aq) twice, and brine once, dried over MgSO4, and filtered, and
the solvent was removed in vacuo. The residue was recrystal-
lized from CH2Cl2/hexanes to afford 18 (0.262 g, 86%) as a
slightly yellow solid: Rf ) 0.27 (hexanes/EtOAc ) 3/1); mp
141-142 °C; IR (KBr) 1358 (m), 2947 (m), 1638 (s), 1085 (s)
cm-1; 1H NMR (CDCl3, 400 MHz) δ 9.84 (s, 1H), 4.38 (m, 4H);
13C NMR (CDCl3, 100 MHz) δ 179.3, 148.1, 140.7, 119.0, 102.2,
65.7, 65.3; HRMS calcd for C7H5SBrO3 247.9143, found
247.9138.
2,3-Dihydro-7-vinylthieno[3,4-b][1,4]dioxine-5-carbal-
dehyde (19). An oven-dried screw-cap tube was charged with
18 (0.262 g, 1.05 mmol), Pd(dba)2 (0.012 g, 0.021 mmol), CuI
(0.0080 0.042 mmol), PPh3 (0.022 g, 0.084 mmol), and BHT
(one crystal). The tube was septum-capped, evacuated, and
back-filled with N2 three times. A solution of vinyltributyltin
(0.399 g, 1.26 mmol) in THF (15 mL) was transferred to the
tube via cannula. The tube was then capped with its screw
cap, and the solution was stirred in oil bath at 80 °C for 44 h.
The reaction mixture was then cooled to room temperature.
KF (0.9 g) in H2O (5 mL) was added. The mixture was stirred
under N2 atmosphere for 20 h, poured into H2O in a separatory
funnel, and the aqueous layer was extracted with EtOAc. The
organic layer was washed with H2O twice, brine twice, dried
over MgSO4, and filtered, and the solvent was removed in
vacuo. The residue was purified by column chromatography,
then recrystallized from EtOAc/hexanes to afford 19 (0.154 g,
75%) as white crystals: Rf ) 0.31 (hexanes/EtOAc ) 3/1); mp
>110 °C dec; IR (KBr) 2951 (m), 1641 (s), 1084 (s), 902 (m)
solidified under refrigeration: Rf ) 0.33 (hexanes/CH2Cl2
)
1
3/1); IR (KBr) 2967 (s), 1699 (s) cm-1; H NMR (CDCl3, 400
MHz) δ 10.20 (s, 1H), 7.76 (s, 1H), 7.59 (s, 1H), 2.94 (q, J )
7.5 Hz, 2H), 2.73 (q, J ) 7.5 Hz, 2H), 1.22 (2t, J ) 7.5 Hz,
6H); 13C NMR (CDCl3, 100 MHz) δ 192.2, 145.7, 145.2, 141.5,
133.8, 130.9, 109.1, 33.9, 25.0, 16.6, 14.7; HRMS calcd for
C11H13IO 288.0011, found 288.0013.
2,5-Diethyl-4-vinylbenzaldehyde (12). An oven-dried
screw-cap tube was charged with Pd(dba)2 (0.0995 g, 0.173
mmol), CuI (0.0659 g, 0.346 mmol), PPh3 (0.181 g, 0.691 mmol),
and BHT (one crystal). The tube was septum-capped, evacu-
ated, and back-filled with N2 three times. A solution of 11 (2.49
g, 8.64 mmol) and vinyltributyltin (3.07 g, 9.68 mmol) in THF
(25 mL) was transferred to the tube via cannula. The tube was
then capped with its screw cap, and the solution was stirred
in an oil bath at 80 °C for 16 h. The reaction mixture was then
cooled to room temperature, and KF (0.8 g) was added. The
mixture was stirred at room temperature overnight and poured
into H2O in a separatory funnel, and the aqueous layer was
extracted with EtOAc. The organic layer was washed with H2O
three times and brine twice, dried over MgSO4, and filtered,
and the solvent was removed in vacuo. The residue was
purified by column chromatography to afford 12 (0.83 g, 51%)
as a clear oil: Rf ) 0.32 (hexanes/CH2Cl2 )2/1); IR (KBr) 2966
(s), 1693 (s), 1604 (m), 919 (s) cm-1; 1H NMR (CDCl3, 400 MHz)
δ 10.25 (s, 1H), 7.64 (s, 1H), 7.40 (s, 1H), 7.00 (dd, J ) 17.4
Hz, 11.0 Hz, 1H), 5.80 (dd, J ) 17.4 Hz, 1.2 Hz, 1H), 5.45 (dd,
J ) 11.0 Hz, 1.1 Hz, 1H), 3.05 (q, J ) 7.5 Hz, 2H), 2.74 (q, J
) 7.6 Hz, 2H), 1.29 (t, J ) 7.5 Hz, 3H), 1.23 (t, J ) 7.5 Hz,
3H); 13C NMR (CDCl3, 100 MHz) δ 192.4, 145.0, 142.1, 140.0,
134.2, 133.2, 132.5, 127.8, 118.4, 26.1, 25.8, 16.9, 15.5; HRMS
calcd for C13H16O 188.1201, found 188.1203.
2,5-Dibutoxy-4-iodobenzaldehyde (15). A solution of 1461
(8.81 g, 18.58 mmol) in diethyl ether (180 mL) was cooled to
-10 °C. To this solution was added dropwise n-BuLi (2.03 M
in hexane, 9.15 mL) over 20 min. The reaction mixture was
stirred in an ice/brine bath at -8 to -5 °C for 1 h. DMF
(anhydrous, 2.2 mL, 29 mmol) was added in one portion. The
reaction mixture was allowed to warm to room temperature
over 6 h and then poured into water in a separatory funnel.
The organic layer was washed with H2O three times and brine
once and dried over MgSO4, and the solvent was removed in
vacuo. After concentration, the yellow oil was diluted with
hexanes (80 mL) and chilled in the refrigerator overnight. The
3416 J. Org. Chem., Vol. 70, No. 9, 2005

Synthesis of Diazonium-Functionalized Oligo(phenylenevinylene)s
cm-1; 1H NMR (CDCl3, 400 MHz) δ 9.91 (s, 1H), 6.75 (dd, J )
17.5 Hz, 11.1 Hz, 1H), 5.75 (dd, J ) 17.5 Hz, 0.5 Hz, 1H), 5.37
(dd, J ) 11.1 Hz, 0.5 Hz, 1H), 4.38 (m, 2H), 4.33 (m, 2H); 13C
NMR (CDCl3, 100 MHz) δ 180.1, 148.9, 139.1, 127.9, 126.0,
117.5, 116.1, 65.7, 64.9; HRMS calcd for C9H8SO3 196.0194,
found 196.0193. Anal. Calcd: C, 55.09; H, 4.11; S, 16.34.
Found: C, 54.81; H, 4.13; S, 16.31.
1051 and 1025 (s) cm-1; 1H NMR (CDCl3, 400 MHz) δ 7.53 (s,
1H), 7.05 (d, JP-H ) 2.6 Hz, 1H), 3.93 (m, 4H), 3.03 (d, JP-H
22.1 Hz, 2H), 2.58 (m, 4H), 1.18-1.10 (m, 12H); 13C NMR
(CDCl3, 100 MHz) δ 143.9 (d, JC-P ) 3.7 Hz), 142.4 (d, JC-P
6.3 Hz), 139.2 (d, JC-P ) 3.2 Hz), 130.9 (d, JC-P ) 5.4 Hz),
130.0 (d, JC-P ) 9.1 Hz), 99.0 (d, JC-P ) 4.7 Hz), 62.2 (d, JC-P
) 6.8 Hz), 33.6, 30.2 (d, JC-P ) 137.8 Hz), 25.1, 16.5 (d, JC-P
) 5.8 Hz), 14.8, 14.7; HRMS calcd for C15H24IO3P 410.0508,
found 410.0514.
)
)
2,5-Diethyl-4-iodobenzoic Acid (22). A solution of 1056
(18.11 g, 46.92 mmol) in THF (200 mL) was cooled to -78 °C.
To this mixture was added dropwise n-BuLi (2.19 M in
hexanes, 21.4 mL) over 40 min. The reaction mixture was
stirred at -78 °C for 1 h. Excess crushed dry ice was poured
into the reaction mixture under a N2 atmosphere. The dry ice
bath was removed, and the reaction mixture was allowed to
warm to room temperature and then quenched with H2O. THF
was removed in vacuo. The residue was transferred into
(2,5-Dibutoxy-4-iodophenyl)methanol (26). To the solu-
tion of 15 (5.96 g, 15.8 mmol) in THF (100 mL) was added
BH3‚THF (1.0 M THF, 19.0 mL) at room temperature. The
mixture was heated at 80 °C for 80 min, then concentrated in
vacuo. The residue was passed through a plug of silica gel to
afford 26 (6.01 g, 100%) as a white crystalline solid: Rf ) 0.35
(hexanes/EtOAc ) 5/1); mp 44.5-45.5 °C; IR (KBr) 3264 (s,
br), 2956 (s), 1205 (s), 1037 (s) cm-1 1H NMR (CDCl3, 500
;
aqueous NaOH (2 M, 200 mL). The basic aqueous layer was
washed with CHCl3 three times, ether once, then acidified by
adding HCl (concd, 40 mL) in an ice bath. A white precipitate
formed during the acidification. The white solid was collected
by filtration, washed with H2O three times, and dried under
vacuum to afford 22 (8.11 g, 57%): mp 134-135 °C (lit.92 mp
MHz) δ 7.25 (s, 1H), 6.83 (s, 1H), 4.64 (s, 2H), 3.98 (t, J ) 6.4
Hz, 2H), 3.96 (t, J ) 6.4 Hz, 2H), 2.32 (br, 1H), 1.79 (2 quint,
J ) 6.5 Hz, 4H), 1.53 (2 sext, J ) 7.5 Hz, 4H), 0.99 (2t, J )
7.5 Hz, 6H); 13C NMR (CDCl3, 125 MHz) δ 152.5, 151.7, 130.9,
122.6, 113.3, 85.4, 70.4, 69.0, 62.3, 31.82, 31.79, 19.80, 19.78,
14.32, 14.30; HRMS calcd for C15H23IO3 378.0692, found
378.0689.
134-135 °C); IR (KBr) 3060-2500 (s), 2970 (m), 1690 (s) cm-1
;
1H NMR (CDCl3, 400 MHz) δ 12.2 (br, 1H), 7.87 (s, 1H), 7.80
(s, 1H), 2.98 (q, J ) 7.5 Hz, 2H), 2.76 (q, J ) 7.5 Hz, 2H), 1.25
(2t, J ) 7.5 Hz, 6H); 13C NMR (CDCl3, 100 MHz) δ 173.2, 146.5,
144.9, 141.9, 131.5, 128.4, 107.7, 34.0, 27.4, 16.2, 14.9; HRMS
calcd for C11H13IO2 303.9960, found 303.9966.
1-(Bromomethyl)-2,5-dibutoxy-4-iodobenzene (27). To
the clear solution of 26 (1.186 g, 3.135 mmol) and PPh3 (0.987
g, 3.76 mmol) in THF (40 mL), was added portionwise NBS
(0.670 g, 3.762 mmol) while stirring in an ice bath. A
precipitate formed immediately. The reaction mixture was
then stirred at room temperature for 40 min and poured into
H2O in a separatory funnel, and the aqueous layer was
extracted with EtOAc. The organic layer was washed with H2O
twice and brine twice, dried over MgSO4, and filtered, and the
solvent was removed in vacuo. The residue was passed through
a plug of silica gel to afford 27 (1.175 g, 85%) as white crystals.
When dried, the white solid immediately turned dark in air.
Compound 27 was reasonably stable in solution but began to
decompose quickly when the pristine solid was isolated. Thus,
some characterization data on this compound could not be
obtained: 1H NMR (CDCl3, 500 MHz) δ 7.28 (s, 1H), 6.82 (s,
1H), 4.52 (s, 2H), 3.99 (2t, J ) 6.4 Hz, 4H), 1.82 (m, 4H), 1.56
(m, 4H), 1.02 and 1.00 (2t, J ) 7.4 Hz, 6H); 13C NMR (CDCl3,
125 MHz) δ 152.4, 151.9, 127.6, 123.7, 114.9, 87.9, 70.3, 69.4,
31.81, 31.79, 29.1, 19.82, 19.76, 14.4, 14.3.
(2,5-Diethyl-4-iodophenyl)methanol (23). To the solu-
tion of 22 (4.57 g, 15.01 mmol) in THF (100 mL), was added
BH3‚THF (1.0 M in THF, 18 mL) at room temperature while
stirring. The reaction mixture was then heated at 75-80 °C
for 2.5 h, cooled to room temperature, and poured into H2O in
a separatory funnel. The mixture was partitioned, and the
aqueous phase was extracted with CH2Cl2 twice. The combined
organic layer was dried over MgSO4 and filtered, and the
solvents were removed in vacuo. The residue was purified by
column chromatography to afford 23 (4.302 g, 99%) as white
crystals: mp 53-55 °C; IR (KBr) 3278 (br), 2962 (m), 1043 (s)
1
cm-1; H NMR (CDCl3, 400 MHz) δ 7.66 (s, 1H), 7.21 (s, 1H),
4.55 (s, 2H, CH2OH, this signal shifts with OH group, could
also be observed at 4.61 when δ-OH ) 2.39), 3.14 (br, 1H),
2.71 (q, J ) 7.5 Hz, 2H), 2.56 (q, J ) 7.5 Hz, 2H), 1.22 (2t, J
) 7.5 Hz, 6H); 13C NMR (CDCl3, 100 MHz) δ 144.3, 141.6,
139.3, 138.7, 128.1, 99.9, 62.4, 34.0, 24.6, 15.4, 15.1; HRMS
calcd for C11H15IO 290.0168, found 290.0165.
Diethyl (2,5-Dibutoxy-4-iodophenyl)methylphospho-
nate (28). The mixture of 27 (1.175 g, 2.663 mmol) and
P(OEt)3 (1.5 mL, 8.7 mmol) was heated in a pressure tube at
150 °C for 4 h. The reaction mixture was cooled to room
temperature and purified by column chromatography to afford
28 (1.282 g, 97%) as a clear oil: Rf ) 0.24 (hexanes/EtOAc )
1-(Bromomethyl)-2,5-diethyl-4-iodobenzene (24). To the
clear solution of 23 (4.302 g, 14.83 mmol) and PPh3 (4.667 g,
17.79 mmol) in THF (80 mL) was added portionwise NBS
(3.167 g, 17.79 mmol) while stirring in an ice bath. A white
precipitate formed immediately. The reaction mixture was
then stirred at room temperature for 15 min, poured into H2O
in a separatory funnel, and the aqueous layer was extracted
with EtOAc. The organic layer was washed with H2O twice
and brine twice, dried over MgSO4, and filtered, and the
solvent was removed in vacuo. The residue was passed through
a plug of silica gel to afford 24 (4.89 g, 93%) as white crystals:
Rf ) 0.43 (hexanes 100%); mp 29-30 °C; IR (KBr) 2965 (s),
1/1); IR (KBr) 2958 (m), 1211 (s), 1028 (s) cm-1 1H NMR
;
(CDCl3, 400 MHz) δ 7.12 (s, 1H), 6.77 (d, JP-H ) 2.6 Hz, 1H),
3.93 (2q, J ) 7.2 Hz, 4H), 3.85 (t, J ) 6.4 Hz, 2H), 3.79 (t, J
) 6.4 Hz, 2H), 3.08 (d, JP-H ) 21.8 Hz, 2H), 1.66 (m, 4H), 1.40
(m, 4H), 1.14 (t, J ) 7.1 Hz, 6H), 0.87 (2t, J ) 7.4 Hz, 6H); 13
C
NMR (CDCl3, 100 MHz) δ 151.9 (d, JP-C ) 3.2 Hz), 151.5 (d,
JP-C ) 7.0 Hz), 122.7 (d, JP-C ) 2.8 Hz), 121.6 (d, JP-C ) 9.1
Hz), 115.3 (d, JP-C ) 5.0 Hz), 84.7 (d, JP-C ) 4.5 Hz), 69.8,
69.0, 62.1 (d, JP-C ) 6.3 Hz), 31.6, 31.5, 26.6 (d, JP-C ) 138.6
Hz), 19.5, 19.4, 16.5 (d, JP-C ) 6.2 Hz), 14.0 (2C, overlap);
HRMS calcd for C19H32IO5P 498.1032, found 498.1035.
1
1209(s) cm-1; H NMR (CDCl3, 500 MHz) δ 7.68 (s, 1H), 7.17
(s, 1H), 4.49 (s, 2H), 2.71 (2q, J ) 7.5 Hz, 4H), 1.29 (t, J ) 7.5
Hz, 3H), 1.23 (t, J ) 7.5 Hz, 3H); 13C NMR (CDCl3, 100 MHz)
δ 144.7, 142.5, 139.9, 135.9, 130.4, 101.8, 33.9, 31.5, 24.7, 15.2,
14.9; HRMS calcd for C11H14BrI 351.9324, found 351.9327.
Diethyl (2,5-Diethyl-4-iodophenyl)methylphosphonate
(25). The mixture of 24 (0.35 g, 0.99 mmol) and P(OEt)3 (2.0
mL, 12 mmol) was heated in a pressure tube at 150-160 °C
for 5 h. Afterward, most of excess P(OEt)3 was removed in
vacuo (∼2 mmHg). The residue was purified by column
chromatography to afford 25 (0.39 g, 96%) as a clear oil: Rf )
0.28 (hexanes/EtOAc ) 1/1); IR (KBr, neat) 2968 (s), 1251 (s),
5-Bromo-1,3-dinitrobenzene (32).70,71 To the mixture of
1,3-dinitrobenzene (29.964 g, 178.24 mmol), Br2 (4.76 mL, 92.7
mmol), and HNO3 (concd 56 mL), cooled in an ice bath, was
added H2SO4 (200 mL) slowly while stirring. The reaction
mixture was heated to 80 °C for 2 h (monitored by TLC, until
minimum starting material remained), cooled to room tem-
perature, and poured into ice. The pale solid was collected by
filtration and washed with H2O until the washings were
neutral. The crude product was recrystallized from EtOH to
give 32 (37.61 g, 85%) as a slightly yellow solid: Rf ) 0.62
(hexanes/EtOAc ) 4/1) (1,3-dinitrobenzene has Rf ) 0.32 on
(92) Sato, O. Bull. Chem. Soc. Jpn. 1957, 30, 702-704.
J. Org. Chem, Vol. 70, No. 9, 2005 3417

Jian and Tour
1
TLC under the same conditions); H NMR (CDCl3, 400 MHz)
35b.96 To mixture of K2CO3 (6.62 g, 48.0 mmol)/HNEt2 (3.3
mL, 32 mmol)/H2O (40 mL), cooled in an ice bath, was added
the solution of 2b47 (5.10 g, 16.0 mmol) in CH3CN (100 mL).
The reaction mixture was stirred in an ice bath that was
allowed to warm to room temperature overnight. The reaction
mixture was poured into water in a separatory funnel and
extracted with EtOAc. The organic layer was washed with H2O
twice and brine once, concentrated in vacuo, and purified by
column to afford 35b (4.75 g, 98%) as an orange oil: Rf ) 0.43
(hexanes/CH2Cl2 ) 3/1); 1H NMR (CDCl3, 400 MHz) δ 7.68 (d,
J ) 8.6 Hz, 2H), 7.24 (d, J ) 8.6 Hz, 2H), 3.77 (q, J ) 7.1 Hz,
4H), 1.30 (br-t, J ) 7.1 Hz, 6H); 13C NMR (CDCl3, 100 MHz)
δ 151.4, 138.2, 123.0, 89.5.
δ 9.03 (t, J ) 2.0 Hz, 1H), 8.74 (d, J ) 2.0 Hz, 2H).
5-Iodo-1,3-dinitrobenzene (33).93,94 A screw-cap tube
charged with 32 (3.029 g, 12.26 mmol), NaI (3.677 g, 24.53
mmol), and CuI (0.117 g, 0.613 mmol) was evacuated and back-
filled with N2 three times. N,N′-Dimethylethylenediamine
(0.13 mL, 1.2 mmol) was added via syringe, followed by 1,4-
dioxane (50 mL, previously dried over 4 Å molecular sieves
and flushed with N2 for at least 2 h). The tube was sealed with
its screw cap and heated at 110 °C for 31 h. The reaction
mixture was cooled back to room temperature, diluted with
aqueous ammonia (30%, 8 mL), poured into water in a
separatory funnel, and extracted with EtOAc. The organic
layer was washed with H2O three times and brine once, dried
over MgSO4, and filtered and the solvent removed in vacuo.
The residue was purified by column chromatography to give
33 (3.28 g, 91%) as a white solid: Rf ) 0.44 (hexanes/EtOAc
) 8/1); mp 102-103 °C (lit.90 mp 104.5-105.5 °C, lit.91 mp
101-102 °C); 1H NMR (CDCl3, 400 MHz) δ 9.04 (t, J ) 2.0
Hz, 1H), 8.90 (d, J ) 2.0 Hz, 2H); 13C NMR (CDCl3, 100 MHz)
δ 149.0, 138.2, 118.9, 93.9.
35c. To the mixture of K2CO3 (6.46 g, 46.8 mmol)/HNEt2
(3.6 mL, 35 mmol)/CH3CN (80 mL), cooled in ice bath, was
added portionwise 2c (7.86 g, 23.4 mmol). The reaction mixture
was then stirred in an ice bath that was allowed to warm to
room temperature overnight. The reaction mixture was poured
into H2O in a separatory funnel and extracted with EtOAc.
The organic layer was washed with H2O twice and brine once,
concentrated in vacuo, and purified by column to afford 35c
(6.76 g, 90%, a yield as high as 98% was obtained) as an orange
oil: Rf ) 0.52 (hexanes/CH2Cl2 ) 3/1); IR (KBr, neat) 2975
3,5-Dinitrostyrene (34).95 A two-neck flask charged with
ZnCl2 (2.34 g, 17.2 mmol) under vacuum was heated over a
Bunson burner until the ZnCl2 melted and began to sublime.
The flask was then allowed to cool to room temperature under
vacuum and back-filled with N2. THF (10 mL) was added via
syringe to dissolve the ZnCl2. The white slurry was cooled to
0 °C, and vinylmagnesium bromide (1M in THF, 10.3 mL) was
added slowly over 10 min. The mixture was then stirred at
room temperature for 1 h. A solution of 33 (2.02 g, 6.87 mmol),
Pd(PPh3)2Cl2 (0.0964 g, 0.137 mmol), and BHT (one crystal)
in THF (50 mL) was cannulated into the mixture above. The
reaction mixture was stirred at room temperature for 18 h and
quenched with NH4Cl (satd aq, 10 mL). The mixture was
poured into water in a separatory funnel and extracted with
CH2Cl2 three times. The combined organic layer was dried over
MgSO4 and filtered, and the solvent was removed in vacuo.
The residue was purified by column chromatography to afford
34 (1.19 g, 89%) as a slightly yellow solid: Rf ) 0.38 (hexanes/
EtOAc ) 8/1); mp 89-90 °C (lit.92 mp 88 °C); IR (KBr) 3098
(m), 1534 (s), 1345 (s), 907 (s) cm-1; 1H NMR (CDCl3, 400 MHz)
δ 8.91 (t, J ) 2.0 Hz, 1H), 8.56 (d, J ) 2.0 Hz, 2H), 6.87 (dd,
J ) 17.5, 11.1 Hz, 1H), 6.10 (d, J ) 17.5 Hz, 1H), 5.68 (d, J )
11.1 Hz, 1H); 13C NMR (CDCl3, 100 MHz) δ 149.3, 141.7, 133.4,
126.3, 120.8, 117.8; HRMS calcd for C8H6N2O4 194.0328, found
194.0326.
1
(m), 1476-1102 (m) cm-1; H NMR (CDCl3, 500 MHz) δ 7.44
3
4
3
(dd, JF-H ) 10.3 Hz, JH-H ) 1.9 Hz, 1H), 7.39 (dm, JH-H
)
8.5 Hz, 1H), 7.20 (t, 4JF-H ) 3JH-H ) 8.4 Hz, 1H), 3.79 (q, J )
7.2 Hz, 4H), 1.33 and 1.26 (2 br, 6H); 13C NMR (CDCl3, 125
MHz) δ 156.5 (d, JC-F ) 252.8 Hz), 139.8 (d, JC-F ) 7.5 Hz),
133.7 (d, JC-F ) 3.8 Hz), 125.7 (d, JC-F ) 22.9 Hz), 121.1 (d,
JC-F ) 2.4 Hz), 87.7 (d, JC-F ) 7.6 Hz); 19F NMR (CDCl3, 470
MHz) δ -126.2 (m, 1F); HRMS calcd for C10H13IN3F 321.0138,
found 321.0136.
35d. To the mixture of K2CO3 (2.86 g, 20.8 mmol)/HNEt2
(1.6 mL, 16 mmol)/H2O (50 mL)/CH3CN (50 mL), cooled in ice
bath, was portionwise added 2d48 (4.01 g, 10.4 mmol). The
reaction mixture was then stirred in an ice bath that was
allowed to warm to room temperature overnight. The reaction
mixture was poured into H2O in a separatory funnel and
extracted with EtOAc. The organic layer was washed with H2O
twice and brine once, concentrated in vacuo and purified by
column to afford 35d (3.40 g, 88%) as a red oil: Rf ) 0.25
(hexanes 100%); IR (KBr, neat): 2977 (m), 1467-1139 (m)
1
cm-1; H NMR (CDCl3, 400 MHz) δ 7.97 (d, J ) 1.9 Hz, 1H),
7.77 (dd, J ) 8.6 Hz, 1.9 Hz, 1H), 7.39 (d, J ) 8.6 Hz, 1H),
3.84-3.75 (m, 4H), 1.37 (q, J ) 7.1 Hz, 3H), 1.24 (q, J ) 6.9
Hz, 3H); 13C NMR (CDCl3, 100 MHz) δ 149.1, 141.4, 135.4 (q,
35a. To the dark solution of 1a (13.22 g, 53.50 mmol) in a
mixed solvent of H2O-CH3CN (1:1, 100 mL), cooled in ice bath,
was added HCl (concd, 17.7 mL). A precipitate formed at once.
To the mixture above, while efficiently stirring, was added
dropwise a solution of NaNO2 (5.538 g, 80.26 mmol) in H2O
(20 mL) over 20 min. The dark red mixture was stirred at 0
°C for 15 min, room temperature 1.5 h, then poured into a
solution of K2CO3 (36.9 g, 267 mmol)/HNEt2 (11.0 mL, 107
mmol)/H2O (100 mL). The resulting mixture was stirred at
room temperature for 2 h, poured into H2O in a separatory
funnel, and extracted with CH2Cl2 three times. The combined
organic layer was dried over MgSO4, filtered, and the solvent
was removed in vacuo. The residue was purified by column to
give 35a (14.34 g, 81%) as a dark orange oil: Rf ) 0.25
JC-F ) 5.7 Hz), 125.7 (q, JC-F ) 29.8 Hz), 123.8 (q, JC-F
)
272.7 Hz), 119.6, 87.5, 49.9, 42.6, 14.9, 11.5; 19F NMR (CDCl3,
470 MHz) δ -60.8 (s, 3F); HRMS calcd for C11H13IN3F3
371.0106, found 371.0102.
4-[4-(3,3-Diethyl)triazene]styrylbenzaldehyde (36). Ac-
cording to the general coupling procedure C, 35b (1.271 g,
4.193 mmol) was coupled with 954 (0.554 g, 4.19 mmol) in the
presence of Pd(OAc)2 (0.047 g, 0.21 mmol), P(o-tolyl)3 (0.256
g, 0.841 mmol), DMF (20 mL), and NBu3 (5.0 mL, 21 mmol)
at 90 °C for 49 h to give 36 (0.79 g, 61%) as a yellow solid: Rf
) 0.41 (hexanes/EtOAc ) 5/1); mp 149-150 °C; IR (KBr) 2936
(m), 2977 (m), 1696 (s), 970 (s), 835 (s) cm-1; 1H NMR (CDCl3,
400 MHz) δ 10.00 (s, 1H), 7.87 (d, J ) 8.2 Hz, 2H), 7.65 (d, J
) 8.2 Hz, 2H), 7.53 (d, J ) 8.5 Hz, 2H), 7.46 (d, J ) 8.5 Hz,
2H), 7.28 (d, J ) 16.3 Hz, 1H), 7.11 (d, J ) 16.3 Hz, 1H), 3.81
(q, J ) 7.1 Hz, 4H), 1.31 (t, J ) 7.1 Hz, 6H); 13C NMR (CDCl3,
100 MHz) δ 192.0, 151.9, 144.3, 135.4, 133.7, 132.7, 130.7,
128.0, 127.1, 126.2, 121.2; HRMS calcd for C19H21N3O 307.1685,
found 307.1686.
(hexanes 100%); IR (KBr, neat) 2970 (m), 1465-1202 (m) cm-1
;
1H NMR (CDCl3, 400 MHz) δ 7.56 (d, J ) 2.1 Hz, 1H), 7.49
(dd, J ) 2.1 Hz, 8.4 Hz, 1H), 7.17 (d, J ) 8.4 Hz, 1H), 3.78 (q,
J ) 7.1 Hz, 4H), 2.85 (q, J ) 7.5 Hz, 2H), 1.31 (t-br, J ) 7.0
Hz, 6H), 1.26 (t, J ) 7.5 Hz, 3H); 13C NMR (CDCl3, 100 MHz)
δ 148.6, 141.4, 138.1, 135.6, 118.9, 89.9, 25.0, 15.7; HRMS calcd
for C12H18IN3 331.0545, found 331.0544.
37. According to the general HWE reaction procedure, 36
(0.096 g, 0.31 mmol), 2163 (0.130 g, 0.350 mmol), NaH (0.014
g, 60% in mineral oil, 0.34 mmol), and DME (10 mL) gave 37
(93) Wolff, J. J.; Gredel, F.; Oeser, T.; Irngartinger, H.; Pritzkow,
H. Chem. Eur. J. 1999, 5, 29-38.
(94) Segura, P.; Bunnett, J. F.; Villanova, L. J. Org. Chem. 1985,
50, 1041-1045.
(96) Yamaguchi, Y.; Kobayashi, S.; Amita, N.; Wakamiya, T.;
Matsubara, Y.; Sugimoto, K.; Yoshida, Z. Tetrahedron Lett. 2002, 43,
3277-3280.
(95) Yates, K.; Leung, H. W. J. Org. Chem. 1980, 45, 1401-1406.
3418 J. Org. Chem., Vol. 70, No. 9, 2005

Synthesis of Diazonium-Functionalized Oligo(phenylenevinylene)s
(0.13 g, 81%) as a yellow solid: Rf ) 0.41 (hexanes/CH2Cl2 )
) 5/1); mp >145 °C dec; IR (KBr) 2923 (m), 1083 (s) cm-1; 1H
NMR (CDCl3, 400 MHz) δ 7.65 (d, J ) 8.4 Hz, 2H), 7.45 (d, J
) 8.8 Hz, 2H), 7.41 (d, J ) 8.7 Hz, 2H), 7.20 (d, J ) 8.4 Hz,
2H), 7.18 (d, J ) 16.1 Hz, 1H), 7.13 (d, J ) 16.1 Hz, 1H), 6.86
(d, J ) 16.2 Hz, 1H), 6.73 (d, J ) 16.2 Hz, 1H), 4.33 (s, 4H),
3.79 (q, J ) 7.0 Hz, 4H), 1.30 (t, J ) 7.1 Hz, 6H); decomposed
while obtaining 13C NMR in CDCl3.
1/1); mp >200 °C dec; IR (KBr) 2918 (m), 968 (s), 838 (s) cm-1
;
1H NMR (CDCl3, 400 MHz) δ 7.70 (d, J ) 8.4 Hz, 2H), 7.54-
7.43 (m, 8H), 7.28 (d, J ) 8.3 Hz, 2H), 7.18-7.00 (m, 4H), 3.81
(q, J ) 7.2 Hz, 4H), 1.30 (t, J ) 7.2 Hz, 6H); the solubility of
this compound was too low to obtain a good 13C NMR; HRMS
calcd for C26H26IN3 507.1171, found 507.1178.
1,4-Dibutoxy-2,5-bischloromethylbenzene (43).97,98
A
38. According to the general HWE reaction procedure, 36
(0.083 g, 0.27 mmol), 25 (0.166 g, 0.405 mmol), NaH (0.0162
g, 60% in mineral oil, 0.405 mmol), and DME (10 mL) at room
temperature for 16 h gave 38 (0.030 g, 20%) as a yellow solid:
Rf ) 0.32 (hexanes/CH2Cl2 ) 3/1); mp 104-106 °C; IR (KBr)
three-neck flask was charged a mixture of 1,4-dibutoxylben-
zene90 (2.609 g, 11.73 mmol), formaldehyde (37% w/w aq, 7.1
mL, 88 mmol), dioxane (30 mL), and HCl (conc, 6.0 mL). The
reaction mixture was heated at 65 °C for 9 h. HCl gas freshly
generated from NaCl and H2SO4 (concd) was continuously
introduced to the reaction mixture throughout the process. The
reaction mixture was cooled back to room temperature, poured
into water, and extracted with EtOAc. The organic layer was
washed with H2O three times, Na2CO3 (satd aq) twice,and
brine once, dried over MgSO4, and filtered and the solvent
removed in vacuo. The residue was purified by flash column
to give 43 (2.75 g, 73%) as white crystals: Rf ) 0.54 (hexanes/
CH2Cl2 ) 3/1); mp 87-88 °C (lit.97 mp 84-86 °C); 1H NMR
(CDCl3, 500 MHz) δ 6.93 (s, 2H), 4.65 (s, 4H), 4.01 (t, J ) 6.4
Hz, 4H), 1.80 (sext, J ) 6.6 Hz, 4H), 1.54 (m, 4H), 1.01 (t, J )
7.3 Hz, 6H); 13C NMR (CDCl3, 100 MHz) δ 151.1, 127.5, 114.8,
69.3, 41.9, 31.9, 19.8, 14.4; HRMS calcd for C16H24Cl2O2
318.1153, found 318.1157.
1
2960 (m), 2924 (m), 960 (s), 833 (m) cm-1; H NMR (CDCl3,
400 MHz) δ 7.67 (s, 1H), 7.53-7.45 (m, 9H), 7.30 (d, J ) 15.9
Hz, 1H), 7.18-7.02 (m, 3H), 3.81 (q, J ) 7.2 Hz, 4H), 2.80-
2.71 (m, 4H), 1.33-1.24 (m, 12H); 13C NMR (CDCl3, 100 MHz)
δ 151.3, 144.6, 141.8, 139.9, 137.7, 136.9, 136.6, 134.6, 130.6,
129.2, 127.6, 127.4, 127.22, 127.17, 125.9, 125.5, 121.2, 99.8,
34.2, 26.1, 15.7, 15.3; HRMS calcd for C30H34IN3 563.1797,
found 563.1799.
39. According to the general coupling procedure C, 38 (41
mg, 0.073 mmol), styrene (0.083 mL, 0.73 mmol), Pd(OAc)2 (0.8
mg, 0.004 mmol), P(o-tolyl)3 (4.4 mg, 0.015 mmol), DMF (5 mL),
and NBu3 (0.26 mL, 1.1 mmol) at 80 °C for 17 h gave 39 (28
mg, 71%) as a yellow solid: Rf ) 0.27 (hexanes/CH2Cl2 ) 2/1);
mp 170-172 °C; IR (KBr) 3022 (m), 2961 (m), 962 (s) cm-1
;
(2,5-Dibutoxy-4-cyanomethylphenyl)acetonitrile (44).99
To the solution of 47 (2.039 g, 6.386 mmol) in DMSO (50 mL)
was added KCN (1.081 g, 16.60 mmol). The reaction mixture
was stirred at room temperature for 8 h and then poured into
cold water in an ice bath. The white precipitate was collected
by filtration, washed thoroughly with H2O, and dried under
vacuum. Recrystallization from EtOH afforded 44 (4.07 g, 78%)
as a white solid: Rf ) 0.15 (hexanes/CH2Cl2 ) 3/1); mp 107-
108 °C (lit.99 106-107 °C); IR (KBr) 2960 (s), 2940 (s), 2250
(s), 1225 (s), 1043 (m) cm-1; 1H NMR (CDCl3, 400 MHz) δ 6.93
(s, 2H), 4.00 (t, J ) 6.4 Hz, 4H), 3.71 (s, 4H), 1.80 (sext, J )
6.4 Hz, 4H), 1.51 (m, 4H), 1.00 (t, J ) 7.4 Hz, 6H); 13C NMR
(CDCl3, 100 MHz) δ 150.5, 119.6, 118.3, 113.1, 69.1, 31.8, 19.8,
19.1, 14.3; HRMS calcd for C18H24N2O2 300.1838, found
300.1838.
1H NMR (CDCl3, 400 MHz) δ 7.58-7.49 (m, 10H), 7.46-7.39
(m, 6H), 7.30 (dm, J ) 7.4 Hz, 1H), 7.19-7.06 (m, 4H), 3.81
(q, J ) 7.2 Hz, 4H), 2.85 (2q, J ) 7.5 Hz, 4H), 1.32 (m, 12H);
13C NMR (CDCl3, 100 MHz, 1 aliphatic and 2 aromatic peaks
missing because of overlap, triazene N-ethyl carbons were
broadened and not observed) δ 151.3, 140.3, 138.3, 137.5,
137.3, 135.6, 135.5, 134.6, 130.0, 129.7, 129.2, 129.0, 128.0,
127.6, 127.3, 127.2, 127.0, 126.5, 126.44, 126.41, 126.0, 121.1,
26.8 (2 Cs overlap), 16.22, 16.20; HRMS calcd for C38H41N3
539.3300, found 539.3300.
2,5-Dibutoxyl-4-[4-(3,3-diethyl)triazene]styrylbenzal-
dehyde (40). According to the general coupling procedure C,
16 (0.754 g, 2.73 mmol) coupled with 35b (0.992 g, 3.27 mmol)
in the presence of Pd(OAc)2 (0.0294 g, 0.131 mmol), P(o-Toly)3
(0.159 g, 0.523 mmol), NBu3 (3 mL, 16 mmol), and DMF (15
mL), at 80 °C for 19 h, to give 40 (0.372 g, 30%) as a yellow
solid: Rf ) 0.29 (hexanes/CH2Cl2 ) 1/1); mp 97-98 °C; IR
1,4-Bis[1-cyano-2-{(3,4-(ethylenedioxy)thien-2-yl}vinyl]-
2,5-dibutoxybenzene (45). To the mixture of 44 (0.118 g,
0.394 mmol), 19 (0.134 g, 0.787 mmol), and MeOH (40 mL)
was added NaOMe (0.043 g, 0.787 mmol). The reaction mixture
was heated at 60 °C for 25 h. MeOH was removed in vacuo.
The residue was diluted with CH2Cl2, washed with H2O three
times, dried over MgSO4,and filtered and solvent removed in
vacuo. The residue was recrystallized in MeOH to give 45
(0.128 g, 54%) as a yellow solid: Rf ) 0.52 (hexanes/EtOAc )
2/1); mp > 200 °C dec; IR (KBr) 2959 (m), 2209 (s), 1216 (s),
1
(KBr) 2955 (s), 2934 (s), 1669 (s), 1205 (s), 978 (m) cm-1; H
NMR (CDCl3, 400 MHz) δ 10.46 (s, 1H), 7.54 (d, J ) 8.4 Hz,
2H), 7.47-7.43 (m, 3H), 7.34 (s, 1H), 7.28 (s, 1H), 7.22 (d,
J ) 17.0 Hz, 1H), 4.14 (t, J ) 6.4 Hz, 2H), 4.06 (t, J ) 6.5
Hz, 2H), 3.80 (q, J ) 7.2 Hz, 4H), 1.89-1.84 (m, 4H), 1.60-
1.54 (m, 4H), 1.30 (t, J ) 7.1 Hz, 6H), 1.03 (t, J ) 7.3 Hz, 3H),
1.03 (t, J ) 7.4 Hz, 3H); 13C NMR (CDCl3, 100 MHz) δ 189.6,
156.8, 151.8, 151.1, 135.3, 134.5, 132.8, 128.1, 124.4, 121.8,
121.2, 110.7, 110.5, 69.35, 69.27, 31.8 (2C, overlap), 19.9, 19.8,
14.4, 14.3; HRMS calcd for C27H37N3O3 451.2835, found
451.2841.
1
1067 (s), 850 (m) cm-1; H NMR (CDCl3, 400 MHz) δ 8.26 (s,
2H), 7.11 (s, 2H), 6.63 (s, 2H), 4.33 (m, 4H), 4.27 (m, 4H), 4.08
(t, J ) 6.1 Hz, 4H), 1.87 (m, 4H), 1.57 (m, 4H), 1.00 (t, 6H, J
) 7.3 Hz); 13C NMR (CDCl3, 100 MHz) δ 151.0, 144.8, 141.9,
135.1, 124.2, 119.5, 114.7, 114.4, 105.5, 101.8, 69.7, 65.7, 65.0,
31.9, 19.9, 14.5; HRMS calcd for C32H32N2O6S2 604.1702, found
604.1690.
41. According to the general coupling procedure A, 35b
(0.276 g, 0.991 mmol), 19 (0.149 g, 0.759 mmol), Pd(OAc)2 (5.2
mg, 0.023 mmol), n-Bu4NBr (0.245 g, 0.759 mmol), i-PrNEt2
(0.8 mL, 5 mmol), DMF (10 mL), and a crystal of BHT gave
41 (0.20 g, 72%). Recrystallization from CH2Cl2/hexanes af-
forded bronze shiny crystals: Rf ) 0.25 (hexanes/EtOAc ) 3/1);
mp 179.5-180.5 °C; IR (KBr) 2972 (m), 1628 (s), 1274 (s), 1080
(s) cm-1; 1H NMR (CDCl3, 400 MHz) δ 9.89 (s, 1H), 7.47 (d, J
) 8.7 Hz, 2H), 7.42 (d, J ) 8.6 Hz, 2H), 7.14 (d, J ) 16.2 Hz,
1H), 7.09 (d, J ) 16.2 Hz, 1H), 4.39 (m, 2H), 4.37 (m, 2H),
3.79 (q, J ) 7.1 Hz, 4H), 1.29 (br-t, J ) 6.8 Hz, 6H); 13C NMR
(CDCl3, 100 MHz) δ 179.8, 152.0, 149.2, 138.8, 133.5, 132.3,
129.3, 128.0, 121.3, 116.2, 115.6, 65.9, 65.0; HRMS calcd for
C19H21SN3O3 371.1304, found 371.1304.
4-[3-Ethyl-4-(3,3-Diethyl)triazene]styrylbenzalde-
hyde (46). According to the general coupling procedure A,
35a (1.48 g, 4.47 mmol), 954 (0.537 g, 4.06 mmol), Pd(OAc)2,
n-Bu4NBr (1.31 g, 4.06 mmol), NBu3 (2.9 mL, 12 mmol), and
DMF (20 mL) at 95 °C for 32 h gave 46 (0.690 g, 46%) as a
dark sticky oil: Rf ) 0.30 (hexanes/CH2Cl2 ) 1/1); IR (KBr)
2969 (m), 1696 (s), 1593 (m), 1096 (m) cm-1; 1H NMR (CDCl3,
500 MHz) δ 9.97 (s, 1H), 7.84 (d, J ) 8.2 Hz, 2H), 7.61 (d, J )
(97) Ndayikengurukiye, H.; Jacobs, S.; Tachelet, W.; Looy, J. V. D.;
Pollaris, A.; Geise, H. J.; Claeys, M.; Kauffmann, J. M.; Janietz, S.
Tetrahedron 1997, 53, 13811-13828.
42. According to the general HWE reaction procedure, 41
(0.016 g, 0.043 mmol), 2163 (0.031 g, 0.086 mmol), NaH (5.2
mg, 60% in mineral oil, 0.13 mmol), and DMF (10 mL) gave
42 (0.021 g, 85%) as an orange solid: Rf ) 0.26 (hexanes/EtOAc
(98) Mel’nikov, N. N.; Prilutskaya, M. V. Zh. Obshch. Khim. 1959,
29, 3746-3747.
(99) Prilutskaya, M. V.; Mel’nikov, N. N. Chem. Abstr. 1960, 8692.
J. Org. Chem, Vol. 70, No. 9, 2005 3419

Jian and Tour
8.2 Hz, 2H), 7.49 (d, J ) 8.3 Hz, 1H), 7.42 (d, J ) 1.8 Hz, 1H),
7.38 (dd, J ) 8.3 Hz, 2.0 Hz, 1H), 7.24 (d, J ) 16.3 Hz, 1H),
7.08 (d, J ) 16.3 Hz, 1H), 3.80 (q, J ) 7.2 Hz, 4H), 2.95 (q, J
) 7.5 Hz, 2H), 1.34-1.30 (m, 9H); 13C NMR (CDCl3, 125 MHz)
δ 191.7, 149.1, 144.2, 139.2, 135.2, 133.5, 132.8, 130.4, 128.2,
126.9, 125.7, 125.5, 117.0, 25.3, 15.8; HRMS calcd for C21H25N3O
335.1998, found 335.1990.
47. According to the general HWE reaction procedure, 46
(0.705 g, 2.10 mmol), 2163 (0.992 g, 2.73 mmol), NaH (0.420 g,
60% in mineral oil, 10.5 mmol), and THF (60 mL) at room
temperature for 2.5 h gave 47 (0.426 g, 38%) as a yellow
solid: Rf ) 0.34 (hexanes/CH2Cl2 ) 3/1); mp 182-183 °C; IR
1
(KBr) 3017 (m), 2964 (m), 1087 (s), 965 (s), 834 (s) cm-1; H
NMR (CDCl3, 400 MHz) δ 7.70 (d, J ) 8.4 Hz, 2H), 7.52 (m,
4H), 7.42 (d, J ) 8.3 Hz, 1H), 7.38 (d, J ) 1.7 Hz, 1H), 7.35
(dd, J ) 8.3 Hz, 1.7 Hz, 1H), 7.28 (overlap with solvent peak,
d, J ) 8.4 Hz, 2H), 7.18-7.06 (overlap of 4 doublets, J ) 16.3
Hz, 4H), 3.80 (q, J ) 7.2 Hz, 4H), 2.90 (q, J ) 7.5 Hz, 2H),
1.35-1.25 (m, 9H); 13C NMR (CDCl3, 100 MHz) δ 148.6, 139.3,
138.2, 138.0, 137.4, 136.2, 134.5, 129.7, 129.6, 128.6, 127.9,
127.5, 127.4, 127.1, 126.9, 125.3, 117.1, 93.1, 25.5, 16.0; HRMS
calcd for C28H30IN3 535.1484, found 535.1481.
48. A centrifuge tube charged with the solution of 47 (0.121
g, 0.226 mmol) in CH2Cl2 (3 mL) was cooled at 0 °C. To this
solution was added HBF4‚OMe2 (0.11 mL, 0.90 mmol) via a
syringe. The reaction mixture turned red immediately. The
mixture was kept in an ice bath for 30 min, and intermittent
sonication was applied during this period. The reaction
mixture was centrifuged, and the liquid was decanted. The
solid was washed with ether twice, dissolved in a minimum
amount of CH3CN, and precipitated by adding ether. The
diazonium salt 48 (0.053 g, 57%) was collected by filtration as
a red solid: IR (KBr) 2236 (s), 1578 (s), 1051 (s) cm-1; 1H NMR
(DMSO-d6, 500 MHz) δ 8.61 (d, J ) 8.7 Hz, 1H), 8.05 (s, 1H),
8.01 (d, J ) 8.7 Hz, 1H), 7.87-7.71 (m, 7H), 7.55 (d, J ) 16.3
Hz, 1H), 7.45 (d, J ) 8.2 Hz, 2H), 7.35 (m, 2H), 3.05 (q, J )
7.5 Hz, 2H), 1.39 (t, J ) 7.5 Hz, 3H); 13C NMR (DMSO-d6, 125
MHz) δ 150.5, 150.0, 139.3, 138.8, 138.4, 137.4, 136.0, 134.2,
129.59, 129.56, 129.4, 129.2, 128.8, 128.1, 127.2, 126.7, 111.2,
94.8, 25.6, 13.8.
FIGURE 6. HPLC results of the mixture 49a-d. Gradient
conditions: H2O-MeOH (MeOH from 80% to 100% in 20 min).
Compound (retention time): 49a (9.08 min); 49b (12.02 min);
49c (16.45 min); 49d (21.22 min).
49a-d. According to the general coupling procedure A, a
mixture of 8a (0.185 g, 0.283 mmol), 8b (0.221 g, 0.305 mmol),
8c (0.184 g, 0.218 mmol), and 8d (0.202 g, 0.203 mmol) was
coupled with 954 (0.199 g, 1.51 mmol) in the presence of
Pd(OAc)2 (0.0091 g, 0.040 mmol), n-Bu4NBr (0.326 g, 1.01
mmol), NBu3 (0.71 mL, 3.0 mmol), BHT (one crystal), and DMF
(15 mL) to give the mixture of 49a-d as a yellow solid (0.55
g, crude). The product mixture gave four major fluorous peaks
corresponding to the four products in the analytical HPLC
(Figure 6).
49b. According to the general coupling procedure A, 8b
(0.821 g, 1.13 mmol), 954 (0.164 g, 1.24 mmol), Pd(OAc)2 (0.013
g, 0.056 mmol), n-Bu4NBr (0.364 g, 1.13 mmol), NBu3 (0.81
mL, 3.4 mmol), and DMF (15 mL) gave 49b (0.723 g, 88%) as
a yellow solid: Rf ) 0.27 (hexanes/CH2Cl2 ) 3/2); mp 124.5-
125.5 °C; IR (KBr) 2963 (m), 1701 (s), 1592 (m), 1257-1139
(s), 970 (m), 840 (m) cm-1; 1H NMR (CDCl3, 400 MHz) δ 10.01
(s, 1H), 7.88 (d, J ) 8.3 Hz, 2H), 7.67 (d, J ) 8.2 Hz, 2H), 7.55
(d, J ) 8.6 Hz, 2H), 7.50 (d, J ) 8.5 Hz, 2H), 7.31-7.10 (m,
6H), 4.98 (s, 2H), 3.68 (s-br, 2H), 2.93 (m, 2H), 2.39 (m, 2H),
1.71 (t-br, 2H), 0.94 (t, J ) 7.3 Hz, 3H); HRMS calcd for
C33H28F13N3O 729.2025, found 729.2557. Anal. Calcd: C, 54.33;
H, 3.87. Found: C, 54.37; H, 3.82.
FIGURE 7. HPLC results of the mixture 50a-d. Gradient
conditions: H2O-CH3CN (CH3CN from 80% to 100% in 30
min). Compound (retention time): 50a (9.94 min); 50b (13.89
min); 50c (20.67 min); 50d (29.84 min).
mmol), NBu3 (0.38 mL, 1.6 mmol), BHT (one crystal), and DMF
(15 mL) give a mixture of 51a-d as an orange solid (∼0.21 g,
crude). Product analysis by HPLC gave four major fluorous
peaks corresponding to the four coupled products (Figure 8).
The peak attributed to 51a was small, indicating a low yield
or unstable product. 51b, 51c, and 51d were isolated by
preparative HPLC.
51b. Isolated by preparative HPLC on FluoroFlash column;
the overall yield was 50% for three steps (from 8b): mp > 100
°C dec; IR (KBr) 2961 (m), 2926 (m), 1508 (s), 1339 (s), 960
50a-d. According to the general HWE reaction procedure,
the mixture of 49a-d (crude, 0.295 g), 25 (0.313 g, 0.764
mmol), NaH (0.076 g, 60% in mineral oil, 1.9 mmol), and DME
(20 mL) gave 50a-d as a yellow solid (0.16 g, crude). The
analytical HPLC gave four major fluorous peaks corresponding
to the four coupled products (Figure 7).
51a-d. According to the general coupling procedure C, the
mixture of 50a-d (crude, 0.16 g), 3167 (0.048 g, 0.32 mmol),
Pd(OAc)2 (0.0018 g, 0.0078 mmol), P(o-tolyl)3 (0.0096 g, 0.031
1
(m) cm-1; H NMR (CDCl3, 400 MHz) δ 8.26 (d, J ) 8.8 Hz,
2H, Ar-H, o-NO2), 7.68 (d, J ) 8.8 Hz, 2H), 7.59-7.48 (m, 11H),
7.39 (d, J ) 16.0 Hz, 1H, trans alkene-H), 7.28-7.09 (m, 8H),
4.98 (s, 2H, benzyl-H), 3.65 (br-t, 2H, NCH2CH2CH3), 2.96-
2.92 (m, 2H, C6F13CH2CH2-Ar), 2.86 (q, J ) 7.5 Hz, 4H,
Ar-CH2CH3), 2.45-2.33 (m, 2H, C6F13CH2CH2-Ar), 1.72 (br,
2H, NCH2CH2CH3), 1.33 (t, J ) 7.5 Hz, 6H, Ar-CH2CH3), 0.95
(t, 3H, J ) 7.3 Hz, NCH2CH2CH3); 19F NMR (CDCl3, 470 MHz)
3420 J. Org. Chem., Vol. 70, No. 9, 2005

Synthesis of Diazonium-Functionalized Oligo(phenylenevinylene)s
FIGURE 8. HPLC results of the mixture 51a-d. Gradient
conditions: H2O-CH3CN (CH3CN from 80% to 100% in 30
min). Compound (retention time): 51a (9.71 min); 51b (13.56
min); 51c (20.23 min); 51d (29.16 min).
FIGURE 9. HPLC results of the mixture 52a-d. Gradient
conditions: H2O-CH3CN (CH3CN from 85% to 90% in 15 min,
then to 100% in 2 min). Compound (retention time): 52a (5.47
min); 52b (8.78 min); 52c (17.02 min); 52d (22.40 min).
δ -81.3 (t, J ) 10.1 Hz, 3F), -115.1 (m, 2F), -122.4 (m, 2F),
-123.4 (m, 2F), -124.0 (m, 2F), -126.6 (m, 2F); MALDI-TOF
MS m/z (matrix: dithranol) calcd for C52H47F13N4O2 1006.3,
found 1006.2.
(500 MHz, CDCl3) δ 8.07 (d, J ) 8.2 Hz, 2H, Ar-H, o-COOCH3),
7.62 (d, J ) 8.3 Hz, 2H), 7.57-7.50 (m, 10H), 7.42 (d, J )
16.0 Hz, 1H, trans alkene-H), 7.32-7.08 (m, 8H), 4.98 (s,
2H, benzyl-H), 3.96 (s, 3H, Ar-COOCH3), 3.68 (br, 2H,
NCH2CH2CH3), 2.95-2.92 (m, 2H, C6F13CH2CH2-Ar), 2.86 (m,
6H, Ar-CH2CH3), 2.45-2.33 (m, 2H, C6F13CH2CH2-Ar), 1.72
(br, 2H, NCH2CH2CH3), 1.33 (m, 9H, Ar-CH2CH3), 0.95 (t-br,
J ) 7.2 Hz, 3H, NCH2CH2CH3).
51c. Isolated by preparative HPLC on FluoroFlash column;
the overall yield was 46% for three steps (from 8c): mp >120
°C dec; IR (KBr) 2925 (m), 1508 (s), 1339 (s), 1203 (s), 957 (m)
1
cm-1; H NMR (CDCl3, 400 MHz) δ 8.26 (d, J ) 8.8 Hz, 2H,
Ar-H, o-NO2), 7.67 (d, J ) 8.8 Hz, 2H), 7.59-7.47 (m, 8H),
7.41 (d, J ) 16.1 Hz, 1H, trans alkene-H), 7.28-7.06 (m,
10H), 4.99 (s, 2H, benzyl-H), 3.71 (br-t, 2H, NCH2CH2CH3),
2.95-2.92 (m, 2H, C6F13CH2CH2-Ar), 2.86 (q, J ) 7.6 Hz, 4H,
Ar-CH2CH3), 2.45-2.37 (m, 2H, C6F13CH2CH2-Ar), 1.74 (br,
2H, NCH2CH2CH3), 1.33 (t, J ) 7.6 Hz, 6H, Ar-CH2CH3), 0.95
(br, 3H, NCH2CH2CH3); 19F NMR (CDCl3, 470 MHz) δ -81.2
(t, J ) 10.1 Hz, 3F), -115.5 (m, 2F), -121.9 (m, 2F), -122.2
52b. Isolated by preparative HPLC on FluoroFlash column;
the overall yield was 50% for three steps (from 8b): 1H NMR
(500 MHz, CDCl3) δ 8.07 (d, J ) 8.2 Hz, 2H, Ar-H, o-COOCH3),
7.61 (d, J ) 8.3 Hz, 2H), 7.57-7.50 (m, 10H), 7.42 (d, J )
16.0 Hz, 1H, trans alkene-H), 7.32-7.08 (m, 9H), 4.98
(s, 2H, benzyl-H), 3.96 (s, 3H, Ar-COOCH3), 3.68 (br, 2H,
NCH2CH2CH3), 2.95-2.91 (m, 2H, C6F13CH2CH2-Ar), 2.86
(m, 4F), -123.2 (m, 2F), -124.0 (m, 2F), -126.6 (m, 2F),
-128.1 and -128.3 (2m, 1F, cis and trans Ar-F); MALDI-TOF
MS m/z (matrix: dithranol) calcd for C54H46F18N4O2 1124.3,
found 1124.3.
(q, J ) 7.6 Hz, 4H, Ar-CH2CH3), 2.45-2.33 (m, 2H,
C6F13CH2CH2-Ar), 1.72 (br, 2H, NCH2CH2CH3), 1.33 (t,
J ) 7.6 Hz, 6H, Ar-CH2CH3), 0.95 (t-br, J ) 7.2 Hz, 3H,
NCH2CH2CH3).
51d. Isolated by preparative HPLC on FluoroFlash column;
the overall yield was 47% for three steps (from 8d): mp
147-149 °C; IR (KBr) 2925 (m), 1517 (s), 1340 (s), 961 (m)
52c. Isolated by preparative HPLC on FluoroFlash column;
the overall yield was 55% for three steps (from 8c): mp
108-110 °C; IR (KBr) 2960 (m), 1719 (s), 1205 (s), 960 (m)
cm-1; H NMR (CDCl3, 400 MHz) δ 8.26 (d, J ) 8.6 Hz, 2H,
cm-1; H NMR (500 MHz, CDCl3) δ 8.07 (d, J ) 8.2 Hz, 2H,
1
1
Ar-H, o-NO2), 7.81 (m, 1H, Ar-H, o-CF3), 7.68 (d, J ) 8.7 Hz,
2H), 7.59-7.47 (m, 7H), 7.39 (d, J ) 16.0 Hz, 1H, trans al-
kene-H), 7.28-7.09 (m, 10H), 5.03 and 4.98 (2 s, 2H, ben-
zyl-H), 3.77 and 3.64 (2 br, 2H, NCH2CH2CH3), 2.93 (m,
2H, C6F13CH2CH2-Ar), 2.86 (q, J ) 7.5 Hz, 4H, Ar-CH2CH3),
2.39 (m, 2H, C6F13CH2CH2-Ar), 1.79 and 1.59 (2 br, 2H,
NCH2CH2CH3), 1.33 (t, J ) 7.5 Hz, 6H, Ar-CH2CH3), 0.95 (t,
3H, J ) 7.3 Hz, NCH2CH2CH3); 19F NMR (CDCl3, 470 MHz) δ
-60.3 and -60.5 (2 s, 3F, cis and trans Ar-CF3), -81.2 (t, J
) 10.1 Hz, 3F), -115.1 (m, 2F), -122.2 (m, 10F), -123.2 (m,
2F), -124.0 (m, 2F), -126.6 (m, 2F); MALDI-TOF MS m/z
(matrix: dithranol) calcd for C57H46F24N4O2 1274.3, found
1275.5.
Ar-H, o-COOCH3), 7.61 (d, J ) 8.3 Hz, 2H), 7.57-7.50 (m, 8H),
7.42 (d, J ) 16.0 Hz, 1H, trans alkene-H), 7.32-7.21 (m, 6H),
7.12-7.08 (m, 4H), 4.99 (s, 2H, benzyl-H), 3.96 (s, 3H,
Ar-COOCH3), 3.73 (br, 2H, NCH2CH2CH3), 2.93-2.88 (m, 2H,
C6F13CH2CH2-Ar), 2.85 (q, J ) 7.5 Hz, 4H, Ar-CH2CH3), 2.45-
2.33 (m, 2H, C6F13CH2CH2-Ar), 1.75 (br, 2H, NCH2CH2CH3),
1.33 (t, J ) 7.5 Hz, 6H, Ar-CH2CH3), 0.95 (br, 3H, NCH2-
CH2CH3); 19F NMR (CDCl3, 470 MHz) δ -81.2 (t, J ) 10.1
Hz, 3F), -115.1 (m, 2F), -122.2 (m, 2F), -122.4 (m, 4F),
-123.2 (m, 2F), -123.9 (m, 2F), -126.6 (m, 2F), -128.1 and
-128.3 (2m, 1F, cis and trans Ar-F); MALDI-TOF MS m/z
(matrix: dithranol) calcd for C54H45F18N3O2 1109.3, found
1109.5.
52a-d. According to the general coupling procedure C, the
mixture of 50a-d (crude, 0.29 g), 3066 (0.094 g, 0.58 mmol),
Pd(OAc)2 (0.0034 g, 0.015 mmol), P(o-tolyl)3 (0.018 g, 0.060
mmol), NBu3 (0.70 mL, 3.0 mmol), BHT (one crystal), and DMF
(20 mL) give a mixture of 52a-d as a yellow solid (∼0.38 g,
crude). Analytical HPLC analysis gave four major fluorous
peaks corresponding to the four coupled products (Figure 9),
and each was isolated by preparative HPLC.
52d. Isolated by preparative HPLC on FluoroFlash column;
the overall yield was 64% for three steps (from 8d): mp 170-
172 °C; IR (KBr) 2965 (m), 1725 (s), 1212 (s), 961 (m) cm-1
;
1H NMR (CDCl3, 400 MHz) δ 8.06 (d, J ) 8.2 Hz, 2H, Ar-H,
o-COOCH3), 7.81 (m, 1H, Ar-H, o-CF3), 7.68-7.49 (m, 11H),
7.42 (d, J ) 16.1 Hz, 1H, trans alkene-H), 7.32-7.21 (m, 8H),
5.02 and 4.97 (2 s, 2H, benzyl-H), 3.95 (s, 3H, Ar-COOCH3),
3.77 and 3.63 (2 m, 2H, NCH2CH2CH3), 2.93-2.88 (m, 2H,
C6F13CH2CH2-Ar), 2.85 (q, J ) 7.5 Hz, 4H, Ar-CH2CH3), 2.45-
2.33 (m, 2H, C6F13CH2CH2-Ar), 1.78 and 1.63 (2 m, 2H,
52a. Isolated by preparative HPLC on FluoroFlash column;
the overall yield was 50% for three steps (from 8a): 1H NMR
J. Org. Chem, Vol. 70, No. 9, 2005 3421

Jian and Tour
FIGURE 10. HPLC results of the mixture 53a-d. Gradient
conditions: H2O-THF (THF from 70% to 100% in 30 min).
Compound (retention time): 53a (7.53 min); 53b (9.95 min);
53c (13.43 min); 53d (17.46 min).
FIGURE 11. HPLC results of the mixture 54a-d. Gradient
conditions: H2O-THF (THF from 70% to 100% in 30 min).
Compound (retention time): 54a (8.52 min); 54b (10.97 min);
54c (14.43 min); 54d or other C10F21 tagged products (18.02
min).
NCH2CH2CH3), 1.32 (t, J ) 7.5 Hz, 6H, Ar-CH2CH3), 0.97 and
0.90 (2 t, J ) 7.3 Hz, 3H, NCH2CH2CH3); 19F NMR (CDCl3,
470 MHz) δ -60.3 and -60.5 (2 s, 3F), -81.2 (t, J ) 10.1 Hz,
3F), -115.1 (m, 2F), -122.2 (m, 10F), -123.2 (m, 2F), -123.9
(m, 2F), -126.6 (m, 2F); MALDI-TOF MS m/z (matrix: dithra-
nol) calcd for C59H49F24N3O2 1287.3, found 1287.4.
53a-d. According to the general HWE reaction procedure,
the mixture of 49a-d (crude, 0.503 g), 28 (0.611 g, 1.23 mmol),
t-BuOK (0.303 g, 2.70 mmol), and DMF (30 mL) gave 53a-d
as an orange solid (0.55 g, crude). Analysis by HPLC gave four
major fluorous peaks as four coupled products (Figure 10).
From Figure 10, there are a significant number of C10F21
tagged compounds present. Thus, side products of 53d were
formed in this coupling reaction.
54a-d. According to the general coupling procedure C, the
mixture of 53a-d (crude, 0.48 g), 3167 (0.268 g, 1.80 mmol),
Pd(OAc)2 (0.0081 g, 0.036 mmol), P(o-tolyl)3 (0.0438 g, 0.144
mmol), NEt3 (0.70 mL, 5.0 mmol), BHT (one crystal) and
DMF (20 mL) give a mixture of 54a-d as a yellow solid
(∼0.75 g, crude). Analysis by HPLC gave four major fluorous
peaks corresponding to the four coupled products (Figure 11).
From Figure 11, we can see that at least two C4F9 tagged
products were formed, one of which was presumably 54a. The
tetramers 54b and 54c were collected after preparative HPLC.
Because the C10F21 tagged trimer was not pure, the group of
C10F21 peaks was a mixture of compounds and 54d was not
isolated. Only 54b and 54c were isolated by preparative
HPLC.
FIGURE 12. HPLC results of the mixture 55a-d. Gradient
conditions: H2O-THF (THF from 70% to 100% in 30 min).
Compound (retention time): 55a (5.92 min); 55b (8.07 min);
55c (11.46 min); 55d (16.19 min).
54b. Isolated by preparative HPLC on FluoroFlash column;
red solid; the overall yield was 48% for three steps (from
8b): mp 100-102 °C; IR (KBr) 2956 (m), 1513 (s), 1338 (s),
mp 105-107 °C; IR (KBr) 2959 (m), 1513 (s), 1338 (s), 1205
1
(s), 962 (m) cm-1; H NMR (CDCl3, 400 MHz) δ 8.25 (d, J )
1
1205 (s), 963 (m) cm-1; H NMR (500 MHz, CDCl3) δ 8.25 (d,
8.8 Hz, 2H, Ar-H, o-NO2), 7.68-7.64 (m, 3H), 7.59-7.50 (m,
6H), 7.28-7.09 (m, 12H), 4.99 (s, 2H, benzyl-H), 4.13 and
4.10 (2t, J ) 7.4 Hz, 4H, Ar-OCH2CH2CH2CH3), 3.71 (br,
2H, NCH2CH2CH3), 2.98-2.91 (m, 2H, C6F13CH2CH2-Ar),
2.46-2.32 (m, 2H, C6F13CH2CH2-Ar), 1.92 (m, 4H,
Ar-OCH2CH2CH2CH3), 1.75 (br, 2H, NCH2CH2CH3), 1.63 (m,
J ) 8.8 Hz, 2H, Ar-H, o-NO2), 7.70-7.67 (m, 3H), 7.57-7.48
(m, 6H), 7.28-7.08 (m, 13H), 4.99 (s, 2H, benzyl-H), 4.13
and 4.11 (2t, J ) 7.4 Hz, 4H, Ar-OCH2CH2CH2CH3), 3.69 (br,
2H, NCH2CH2CH3), 2.95-2.92 (m, 2H, C6F13CH2CH2-Ar),
2.46-2.34 (m, 2H, C6F13CH2CH2-Ar), 1.93 (m, 4H,
Ar-OCH2CH2CH2CH3), 1.76 (br, 2H, NCH2CH2CH3), 1.63
(m, 4H, Ar-OCH2CH2CH2CH3), 1.07 (t, J ) 7.4 Hz, 6H,
Ar-OCH2CH2CH2CH3), 0.95 (br, 3H, NCH2CH2CH3); 19F NMR
(CDCl3, 470 MHz) δ -81.3 (t, J ) 10.1 Hz, 3F), -115.1 (m,
2F), -122.4 (m, 2F), -123.4 (m, 2F), -124.0 (m, 2F), -126.6
(m, 2F); MALDI-TOF MS m/z (matrix: dithranol) calcd for
C56H55F13N4O4 1094.4, found 1094.6.
4H, Ar-OCH2CH2CH2CH3), 1.07 (t,
J ) 7.4 Hz, 6H,
Ar-OCH2CH2CH2CH3), 0.95 (br, 3H, NCH2CH2CH3); 19F NMR
(CDCl3, 470 MHz) δ -81.2 (t, J ) 10.1 Hz, 3F), -115.1 (m,
2F), -122.2 (m, 2F), -122.4 (m, 4F), -123.2 (m, 2F), -124.0
(m, 2F), -126.6 (m, 2F), -128.1 and -128.3 (2 s, 1F, cis and
trans Ar-F); MALDI-TOF MS m/z (matrix: dithranol) calcd
for C58H54F18N4O4 1212.4, found 1212.5.
54c. Isolated by preparative HPLC on FluoroFlash column;
red solid; the overall yield was 42% for three steps (from 8c):
55a-d. According to the general HWE reaction procedure,
the mixture of 49a-d (0.469 g, crude), 2163 (0.282 g, 0.777
3422 J. Org. Chem., Vol. 70, No. 9, 2005

Synthesis of Diazonium-Functionalized Oligo(phenylenevinylene)s
FIGURE 15. HPLC results of the mixture 59a-d. Gradient
conditions: H2O-THF (THF from 70% to 100% in 30 min).
Compound (retention time): 59a (4.77 min); 59b (6.58 min);
59c (9.53 min); 59d (13.80 min).
FIGURE 13. HPLC results of the mixture 57a-d. Gradient
conditions: H2O-MeOH (MeOH from 80% to 100% in 15 min).
Compound (retention time): 57a (7.78 min); 57b (10.10 min);
57c (13.50 min); 57d (17.12 min).
FIGURE 16. HPLC results of the mixture 60a-d. Gradient
conditions: H2O-THF (THF from 70% to 100% in 30 min).
Compound (retention time): 60a (4.94 min); 60b (7.16 min);
60c (11.31 min); 60d (18.44 min).
FIGURE 14. HPLC results of the mixture 58a-d. Gradient
conditions: H2O-THF (THF from 70% to 100% in 30 min).
Compound (retention time): 58a (5.21 min); 58b (7.34 min);
58c (10.46 min); 58d (15.01 min).
The products mixture gave four major fluorous peaks corre-
sponding to the four coupled products in the analytical HPLC
(Figure 13).
58a-d. According to the general HWE reaction procedure,
the mixture of 57a-d (crude, 0.269 g), 2163 (0.231 g, 0.636
mmol), NaH (0.0382 g, 60% in mineral oil, 0.954 mmol), and
DMF (30 mL) gave 58a-d as an orange solid (0.230 g, crude).
The analytical HPLC gave four major fluorous peaks corre-
sponding to the four coupled products (Figure 14).
59a-d. According to the general coupling procedure C, the
mixture of 58a-d (crude, 0.143 g), 3167 (0.0509 g, 0.341 mmol),
Pd(OAc)2 (1.5 mg, 0.0068 mmol), P(o-tolyl)3 (8.3 g, 0.027 mmol),
NBu3 (0.24 mL, 1.1 mmol), BHT (one crystal), and DMF (20
mL) gave a mixture of 59a-d as a red solid (∼0.19 g, crude).
Analytical HPLC of the product gave four major fluorous peaks
corresponding to the four coupled products (Figure 15).
Because of poor solubility, the preparative HPLC isolation
could only be achieved using THF-based eluents. Only 59d
was successfully isolated. The isolated fractions of 59b and
59c were mixtures of the desired products and side prod-
mmol), NaH (0.072 g, 60% in mineral oil, 1.8 mmol) and DME
(15 mL) gave 55a-d as a yellow solid (0.50 g, crude). The
analytical HPLC gave four major fluorous peaks corresponding
to the four coupled products (Figure 12).
56a-d. According to the general coupling procedure C, the
mixture of 55a-d (0.50 g, crude), 3167 (0.152 g, 1.02 mmol),
Pd(OAc)2 (0.0046 g, 0.020 mmol), P(o-tolyl)3 (0.025 g, 0.082
mmol), NEt3 (0.35 mL, 2.5 mmol), and DMF (10 mL) gave
mixture 56a-d as a yellow solid (0.65 g, crude). The mixture
was extremely insoluble; thus, HPLC analyses were not
obtained.
57a-d. According to the general coupling procedure C, the
mixture of 8a (0.103 g, 0.158 mmol), 8b (0.106 g, 0.146 mmol),
8c (0.078 g, 0.092 mmol), 8d (0.070 g, 0.070 mmol), Pd(OAc)2
(0.0051 g, 0.023 mmol), P(o-tolyl)3 (0.028 g, 0.093 mmol), NBu3
(0.55 mL, 2.3 mmol), BHT (one crystal), and DMF (20 mL)
gave a mixture of 57a-d as an orange solid (0.29 g, crude).
J. Org. Chem, Vol. 70, No. 9, 2005 3423

Jian and Tour
Pd(OAc)2 (0.0011 g, 0.0049 mmol), P(o-tolyl)3 (0.0056 g, 0.018
mmol), NBu3 (0.20 mL, 0.84 mmol), BHT (one crystal), and
DMF (8 mL) gave a mixture of 60a-d as a red solid (∼0.079
g, crude). Analytical HPLC of the product gave four major
fluorous peaks corresponding to the four coupled products
(Figure 16).
61a-d. According to the general coupling procedure C, the
mixture of 58a-d (crude, 0.064 g), styrene (0.020 mL, 0.20
mmol), Pd(OAc)2 (0.0011 g, 0.0049 mmol), P(o-tolyl)3 (0.0061
g, 0.020 mmol), NBu3 (0.20 mL, 0.84 mmol), BHT (one crystal)
and DMF (8 mL) gave a mixture of 61a-d as a red solid. HPLC
analysis of the mixture gave four major fluorous peaks
corresponding to the four coupled products (Figure 17).
62b. The solution of 51b (0.024 g, 0.024 mmol) in CH2Cl2
(2.5 mL) was cooled to 0 °C. HBF4‚OMe2 (0.1 mL, 0.8 mmol)
was added via a syringe. The reaction mixture immediately
turned red. The mixture was stirred in an ice bath for 10 min.
Anhydrous CH3CN (2 mL, twice) was added to extract the
reaction mixture. The solid salt of the amine tag 7b was
isolated from the CH3CN extract, and 7b was recovered after
a basic workup (9.8 mg, 82%). The extraction solution was
concentrated, and adding ether precipitated a red solid. The
precipitate was recrystallized from CH3CN/ether. The diazo-
nium salt 62b (8.6 mg, 60%) was collected by filtration as a
FIGURE 17. HPLC results of the mixture 61a-d. Gradient
conditions: H2O-THF (THF from 70% to 100% in 30 min).
Compound (retention time): 61a (4.99 min); 61b (6.90 min);
61c (10.00 min); 61d (14.44 min).
red solid: IR (KBr) 2928 (m), 2336 (w), 1570 (s), 1373 (s) cm-1
;
1H NMR (CD3CN, 400 MHz) δ 8.38 (d, J ) 9.0 Hz, 2H), 8.22
(d, J ) 8.9 Hz, 2H), 8.02 (d, J ) 9.0 Hz, 2H), 7.78 (d, J ) 8.7
Hz, 2H), 7.73-7.60 (m, 8H), 7.54 (d, J ) 16.2 Hz, 1H), 7.42 (d,
J ) 16.2 Hz, 1H), 7.27 (d, J ) 16.7 Hz, 1H), 7.22 (d, J ) 16.7
Hz, 1H), 2.86 (2q, J ) 7.5 Hz, 4H), 1.26 (2t, J ) 7.5 Hz, 6H);
13C NMR (CD3CN, 100 MHz) δ 152.8, 148.2, 145.8, 142.3,
141.9, 141.2, 140.5, 137.0, 136.3, 135.8, 134.3, 131.4, 130.4,
130.2, 129.9, 128.8, 128.6, 128.5, 128.3, 127.8, 127.6, 126.6,
125.4, 110.1, 27.1 (2C, overlap), 16.7, 16.6.
ucts. MS verified the presence of desired 59b and 59c: 59b,
MALDI-TOF MS m/z (Matrix: dithranol), calcd for
C48H39F13N4O4S 1014.2, found 1014.9; 59c, MALDI-TOF MS
m/z (matrix: dithranol), calcd for C50H38F18N4O4S 1132.2,
found 1132.7.
59d. Isolated by preparative HPLC on FluoroFlash col-
umn; brown solid; the overall yield was 22% for three steps
(from 8d): mp >200 °C dec; IR (KBr) 2923 (m), 1515 (s), 1340
1
(s), 1213 (s) cm-1; H NMR (500 MHz, CDCl3) δ 8.24 (d, J )
Acknowledgment. The work was funded by the
Defense Advanced Research Projects Agency, the Office
of Naval Research, and the National Institute of Stan-
dards and Testing (U.S. Department of Commerce). The
National Science Foundation, CHEM 0075728, provided
partial funding for the 400 MHz NMR.
8.7 Hz, 2H, Ar-H, o-NO2), 7.72 (m, 1H, Ar-H, o-CF3), 7.65
(d, J ) 8.8 Hz, 2H), 7.57-7.48 (m, 5H), 7.32-7.15 (m, 10H),
6.86 (d, J ) 16.1 Hz, 2H, alkene-H), 5.01 and 4.97 (2 s, 2H,
benzyl-H), 4.36 (s, 4H, OCH2CH2O), 3.76 and 3.62 (2-m, 2H,
NCH2CH2CH3), 2.93 (m, 2H, C6F13CH2CH2-Ar), 2.38 (m, 2H,
C6F13CH2CH2-Ar), 1.78 and 1.63 (2m, 2H, NCH2CH2CH3), 0.97
and 0.90 (2m, 3H, NCH2CH2CH3); 19F NMR (CDCl3, 470 MHz)
δ -60.3 and -60.6 (2 s, 3F), -81.2 (t, J ) 10.1 Hz, 3F), -115.1
(m, 2F), -122.2 (m, 10F), -123.2 (m, 2F), -123.9 (m, 2F),
-126.6 (m, 2F); MALDI-TOF MS m/z (matrix: dithranol) calcd
for C53H38F24N4O4S 1282.2, found 1282.9.
Supporting Information Available: 1H, 13C, and 19F
NMR spectra of selected compounds as well as general reaction
procedures. This material is available free of charge via the
Internet at http://pubs.acs.org.
60a-d. According to the general coupling procedure C, the
mixture of 58a-d (crude, 0.061 g), 3066 (0.019 mL, 0.12 mmol),
JO048051S
3424 J. Org. Chem., Vol. 70, No. 9, 2005