Synthesis of functionalized organic second-order nonlinear optical chromophores for electrooptic applications

Article abstract of DOI:10.1021/jo981707v

The design and syntheses of functionalized second-order nonlinear optical chromophores, suitable for covalent incorporation into functionalized high-performance polymers, are described. The chromophores with hydroxy alkyl functionality have diarylamino groups as the donor moiety and a styryl thiophene moiety as the conjugated bridge. The triarylamine parts of the molecules were synthesized using palladium-catalyzed C-N bond forming reactions. The conjugated bridge was assembled using the Wittig reaction. The acceptor groups were installed in the last steps of the syntheses.

Full text of DOI:10.1021/jo981707v

J . Org. Chem. 1999, 64, 4289-4297
4289
Syn th esis of F u n ction a lized Or ga n ic Secon d -Or d er Non lin ea r
Op tica l Ch r om op h or es for Electr oop tic Ap p lica tion s
S. Thayumanavan,† J effrey Mendez,† and Seth R. Marder*,†,‡,§
Beckman Institute, 139-74 California Institute of Technology, Pasadena, California 91125, J et Propulsion
Laboratory, 139-74 California Institute of Technology, Pasadena, California 91125, and Department of
Chemistry, University of Arizona, Tucson, Arizona 85721
Received August 21, 1998
The design and syntheses of functionalized second-order nonlinear optical chromophores, suitable
for covalent incorporation into functionalized high-performance polymers, are described. The
chromophores with hydroxy alkyl functionality have diarylamino groups as the donor moiety and
a styryl thiophene moiety as the conjugated bridge. The triarylamine parts of the molecules were
synthesized using palladium-catalyzed C-N bond forming reactions. The conjugated bridge was
assembled using the Wittig reaction. The acceptor groups were installed in the last steps of the
syntheses.
Electrooptic materials, whose index of refraction can
be changed by the application of an electric field, are of
interest due to their potential for use in applications
including optical data transmission and optical informa-
tion processing.1,2 One of the important components of
these materials is nonlinear optical (NLO) chromo-
phores.3-5 The NLO chromophores can be incorporated
into polymer hosts as guests or they can be covalently
attached to the polymer backbone. Covalent incorporation
of the NLO chromophores is preferred over the host-
guest system, since: (i) sublimation of the NLO chro-
mophores under poling conditions is obviated when they
are covalently incorporated into the polymeric system and
(ii) processibility problems due to phase separation at
high loading is less likely with covalently incorporated
systems.
Covalent incorporation can be achieved by using func-
tionalized NLO chromophores as comonomers in the
polymerization reaction or by attaching the chromophores
to a prefunctionalized polymer under mild reaction
conditions.6 In the former process, the chromophore can
either be a part of the polymer backbone or a side-chain
appendage.7-10 Both of these procedures involve survival
of the NLO chromophores under the often harsh polym-
erization reaction conditions. Therefore, incorporation of
chromophores into a prefunctionalized polymer as a side-
chain appendage using the latter procedure is preferable
† Beckman Institute, California Institute of Technology.
‡ J et Propulsion Laboratory, California Institute of Technology.
§ University of Arizona.
(1) (a) Nonlinear Optical Properties of Organic Molecules and
Crystals; Chemla, D. S., Zyss, J ., Eds.; Academic Press: New York,
1987. (b) Materials for Nonlinear Optics: Chemical Perspectives;
Marder, S. R., Sohn, J . E., Stucky, G. D., Eds.; ACS Symposium Series;
American Chemical Society: Washington, DC, 1991. (c) Optical Non-
linearities in Chemistry. Chem. Rev. 1994 (1). (d) Bosshard, C.; Sutter,
K.; Pretre, P.; Hulliger, J .; Flo¨rsheimer, M.; Kaatz, P.; Gu¨nter, P.
Organic Nonlinear Optical Materials; Gordon & Breach: Basel, 1995.
(e) Polymers for Second-Order Nonlinear Optics; Lindsay, G. A., Singer,
K. D., Eds.; ACS Symposium Series Vol. 601; Amercian Chemical
Society: Washington DC, 1995. (f) Miyata, S.; Sasabe, H. Poled
Polymers and Their Applications to SHG and EO Devices; Gordon and
Breach: Amsterdam, 1997. (g) Kajzar, F.; Swalen, J . Organic Thin
Films for Waveguiding Nonlinear Optics; Gordon & Breach: Amster-
dam, 1996. (h) Nalwa, H. S. Nonlinear Optics of Organic Molecules
and Polymers; CRC Press: Boca Raton, 1997. (i) Kuzyk, M. G.; Singer,
K. D.; Twieg, R. J . J . Opt. Soc. Am. B. Opt. Phys. 1998, 15, 254.
(2) For pertinent reviews, see: (a) Marder, S. R.; Kippelen, B.; J en,
A. K.-Y.; Peyghambarian, N. Nature 1997, 388, 845. (b) Wolff, J . J .;
Wortmann, R. J . Prakt. Chem. 1998, 340, 99. (c) Marks, T. J .; Ratner,
M. A. Angew. Chem., Int. Ed. Engl. 1995, 34, 155. (d) Denning, R. G.
J . Mater. Chem. 1995, 5, 365.
(6) For leading references, see: Dalton, L. R.; Harper, A. W.; Ghosn,
R.; Steier, W. H.; Ziari, M.; Fetterman, H.; Shi, Y.; Mustacich, R. V.;
J en, A. K.-Y.; Shea, K. J . Chem. Mater. 1995, 7, 1060.
(7) For references to main-chain polymers, see: (a) Lindsay, G. A.;
Wynne, K. J .; Stengersmith, J . D.; Chafin, A. P.; Hollins, R. A.; Roberts,
M. J .; Merwin, L. H.; Hermann, W. N. ACS Symp. Ser. 1997, 672, 133.
(b) Hall, H. K., J r.; Kuo, T.; Leslie, T. Macromolecules 1989, 22, 3525.
(c) Robello, D.; Martinez, C. I.; Pangborn, A. B.; Shi, J .; Urankar, E.
J .; Willard, C. S. Polym. Prepr. 1994, 35, 124. (d) Dobler, M.; Weder,
C.; Ahumada, O.; Neuenschwander, P.; Suter, U. W.; Follonier, S.;
Bosshard, C.; Gunter, P. Macromolecules 1998, 31, 7676.
(8) For references to side-chain NLO chromophores, see: (a) Singer,
K. D.; Kuzyk, M. G.; Holland, W. R.; Sohn, J . E.; Lalama, S. J .;
Comizzoli, R. B.; Katz, H. E.; Schilling, M. L. Appl. Phys. Lett. 1988,
53, 1800. (b) Ye, C.; Marks, T. J .; Yang, J .; Wong, G. Macromolecules
1987, 20, 2322. (c) Schilling, M. L.; Katz, H. E.; Cox, D. J . Org. Chem.
1988, 53, 5538. (d) Lindsay, G.; Henry, R.; Hoover, J .; Knoessen, A.;
Mortazavi, M. Macromolecules 1992, 25, 4888. (e) Woo, H. Y.; Shim,
H.-K.; Lee, K.-S.; J eong, M.-Y.; Lim, T.-K. Chem. Mater. 1999, 11, 218.
(9) For the use of multifunctionalized chromophores to synthesize
sol-gel materials, see: (a) Yang, Z.; Xu, C.; Wu, B.; Dalton, L. R.;
Kalluri, S.; Steier, W. H.; Shi, Y.; Bechtel, J . H. Chem. Mater. 1994, 6,
1899. (b) Sung, P.-H.; Hsu, T.-F.; Ding, Y.-H.; Wu, A. Y. Chem. Mater.
1998, 10, 1642 and references therein.
(10) For other related references, see: (a) J en, A. K.-Y.; Drost, K.
J .; Cai, Y.; Rao, V. P.; Dalton, L. R. J . Chem. Soc., Chem. Commun.
1994, 965. (b) J en, A. K.-Y.; Liu, Y.-J .; Cai, Y.; Rao, V. P.; Dalton, L.
R. J . Chem. Soc., Chem. Commun. 1994, 2711. (c) Becker, M. W.;
Sapochak, L. S.; Ghosen, R.; Xu, C.; Dalton, L. R.; Shi, Y.; Steier, W.
H.; J en, A. K.-Y. Chem. Mater. 1994, 6, 104. (d) J en, A. K.-Y.; Wu, X.;
Ma, H. Chem. Mater. 1998, 10, 471. (e) Yu, D.; Yu, L. Macromolecules
1994, 27, 6718. (f) Peng, Z.; Yu, L. Macromolecules 1994, 27, 2638. (g)
Yu, D.; Gharavi, A.; Yu, L. J . Am. Chem. Soc. 1995, 117, 11680. (h)
Saadeh, H.; Gharavi, A.; Yu, L. Macromolecules 1997, 30, 5403.
(3) Singer, K. D.; Kuzyk, M. G.; Holland, W. R.; Sohn, J . E.; Lalama,
S. J .; Cornizzolo, R. B.; Katz, H. E.; Schilling, M. L. Appl. Phys. Lett.
1991, 69, 2568.
(4) (a) Marder, S. R.; Beratan, D. N.; Cheng, L.-T. Science, 1991,
252, 103. (b) Gorman, C. B.; Marder, S. R. Proc. Natl. Acad. Sci. U.S.A.
1993, 90, 11297. (c) Meyers, F.; Marder, S. R.; Pierce, B. M.; Bre´das,
J . L. J . Am. Chem. Soc. 1994, 116, 10703 and references therein.
(5) For examples of second-order nonlinear optical chromophores
with high µâ, see: (a) Ahlheim, M.; Barzoukas, M.; Bedworth, P. V.;
Blanchard-Desce, M.; Fort, A.; Hu, Z.-Y.; Marder, S. R.; Perry, J . W.;
Runser, C.; Staehelin, M.; Zysset, B. Science 1996, 271, 335. (b)
Blanchard-Desce, M.; Alain, V.; Bedworth, P. V.; Marder, S. R.; Fort,
A.; Runser, C.; Barzoukas, M.; Lebus, S.; Wortmann, R. Chem. Eur.
J . 1997, 3, 1091 and references therein. (c) Dirk, C. W.; Katz, H. E.;
Schilling, M. L.; King, L. A. Chem. Mater. 1990, 2, 700. (d) Blanchard-
Desce, M.; Alain, V.; Midrier, L.; Wortmann, R.; Lebus, S.; Glania, C.;
Kra¨mer, P.; Fort, A.; Muller, J .; Barzoukas, M. J . Photochem. Photobiol.
A 1997, 105, 115.
10.1021/jo981707v CCC: $18.00 © 1999 American Chemical Society
Published on Web 05/25/1999

4290 J . Org. Chem., Vol. 64, No. 12, 1999
Thayumanavan et al.
in many cases.11 This process commonly involves incor-
poration of hydroxy functionalized chromophores into
polymers with phenolic functionalities under Mitsunobu
reaction conditions.12
nated (diarylamino)aryl carboxaldehydes 3-5.17 The
main skeletons of the chromophores were then assembled
by Wittig reactions with a thiophene phosphonium salt
6. The acceptor moieties were installed in the last or the
penultimate step of the synthesis.
The required noncentrosymmetric alignment of chro-
mophores in organic electrooptic materials is achieved
by electric poling at temperatures near the glass transi-
tion temperature (Tg) of the host polymer. Therefore, it
is imperative that the NLO chromophores possess high
thermal stabilities. It has been recently shown that
substitution of the diarylamino group as the donor in
place of the dialkylamino group improves the thermal
stabilities of the chromophores without a major compro-
mise in optical nonlinearities.13-15 Using this design
principle, we have recently demonstrated that chro-
mophores represented by structure 1 exhibit enhanced
photochemical stabilities in addition to high optical
nonlinearities and thermal stabilities when compared to
the corresponding dialkylamino donor-based chromo-
phores.16 We also observed that the incorporation of an
additional methoxy group on the bridging phenyl ring
(represented by 2) further enhances the optical nonlin-
earity without any major effect on the thermal and
photochemical stabilities. Therefore, we chose to incor-
porate hydroxy alkyl functionality on the aryl rings in
the chromophores of the types represented by 1 and 2.
In this paper, we describe the syntheses of these hydroxy-
functionalized chromophores with tricyanovinyl, dicy-
anovinyl, or 3-phenylisoxazolone moieties as acceptors.
The triarylamines were assembled using the pal-
ladium-catalyzed aryl carbon-nitrogen bond-forming
reaction reported in the literature recently.18 We realized
that this methodology can be used to rapidly assemble
unsymmetrically substituted triarylamines by a sequen-
tial addition of aryl bromides to the anilines.19 To
synthesize 3, aniline was treated sequentially with the
aryl bromides 7 and 8 in the presence of sodium tert-
butoxide and catalytic amounts of tris(dibenzylidene-
acetone)dipalladium (Pd2(dba)3) and 1,1′-bis(diphenylphos-
phino)ferrocene (DPPF) to afford the triarylamine prod-
uct 9 in 72% yield.19 The allylic double bond in the
compound 9 was hydroborated using 9-BBN, which after
oxidative workup afforded the corresponding alcohol. The
alcohol was then protected as the TBS ether to afford
the compound 10 in 66% overall yield. Compound 10 was
then treated with N-bromosuccinimide in DMF to bro-
minate the only available para position of the triaryl-
amine. Bromine-lithium exchange followed by treatment
with DMF provided the aldehyde 3 in 75% yield.20 The
synthetic approach is outlined in Scheme 1.
To synthesize the triarylaminecarboxaldehyde 4, we
utilized the one-pot triarylamine synthetic strategy with
4-butylaniline, bromobenzene, and 1,4-dibromobenzene
to obtain the brominated triarylamine 11 in 75% yield.
Treatment of the compound 11 with tert-butyllithium
followed by 6-bromohex-1-ene afforded the triarylamine
12 in 73% yield. Hydroboration followed by oxidation
afforded the corresponding primarily alcohol, which was
then protected as a TBS ether 13 as shown in Scheme
2.21
Resu lts a n d Discu ssion
The syntheses of these chromophores were approached
in a convergent fashion. The functionalized triarylamine
parts of the chromophores were synthesized as tert-
butyldimethylsilyl (TBS)-protected hydroxyalkyl termi-
(11) (a) Chen, T.-A.; J en, A. K.-Y.; Cai, Y. J . Am. Chem. Soc. 1995,
117, 7295. (b) Chen, T.-A.; J en, A. K.-Y.; Cai, Y. Macromolecules 1996,
29, 535.
(12) Mitsunobu, O. Synthesis 1981, 1.
(13) (a) Moylan, C. R.; Twieg, R. J .; Lee, V. Y.; Swanson, S. A.;
Betterton, K. M.; Miller, R. D. J . Am. Chem. Soc. 1993, 115, 12599.
(b) Twieg, R. J .; Burland, D. M.; Hedrick, J .; Lee, V. Y.; Miller, R. D.;
Moylan, C. R.; Seymour, C. M.; Volkson, C. A.; Walsh, C. A. Proc. SPIE
1994, 2, 2143.
(14) (a) J en, A. K.-Y.; Cai, Y.; Bedworth, P. V.; Marder, S. R. Adv.
Mater. 1997, 9, 132. (b) Bedworth, P. V.; Cai, Y.; J en, A.; Marder, S.
R. J . Org. Chem. 1996, 61, 2242. (c) Wu, X.; Wu, J .; Liu, Y.; J en, A.
K.-Y. J . Am. Chem. Soc. 1999, 121, 472.
(15) For the covalent incorporation of a diarylamino donor-based
chromophore into a polymeric system, see: (a) Verbiest, T.; Burland,
D. M.; J urich, M. C.; Lee, V. Y.; Miller, R. D.; Volksen, W. Science 1995,
268, 1604. (b) Verbiest, T.; Burland, D. M.; J urich, M. C.; Lee, V. Y.;
Miller, R. D.; Volksen, W. Macromolecules 1995, 28, 3005. (c) Miller,
R. D.; Burland, D. M.; J urich, M.; Lee, V. Y.; Moylan, C. R.; Thackara,
J . I.; Twieg, R. J .; Verbiest, T.; Volksen, W. Macromolecules 1995, 28,
4970.
(17) We are interested in analyzing the effect of the additional
ethereal linkage, such as in 5, on the stability of the chromophores.
Therefore, we targeted both 3 and 4 to analyze the effect of an
additional ethereal linkage in the absence of other variables.
(18) (a) Driver, M. S.; Hartwig, J . F. J . Am. Chem. Soc. 1996, 118,
7217. (c) Wolfe, J . P.; Wagaw, S.; Buchwald, S. L. J . Am. Chem. Soc.
1996, 118, 7215. For a recent review, see: (c) Hartwig, J . F. Angew.
Chem., Int. Ed. Engl. 1998, 37, 2046.
(19) Thayumanavan, S.; Barlow, S.; Marder, S. R. Chem. Mater.
1997, 9, 3231.
(20) Application of Vilsmeier-type reaction conditions to synthesize
3 from 10 resulted in the conversion of the -OTBS group to the -Cl
group.
(16) Thayumanavan, S. et al. Manuscript in preparation.

Synthesis of Second-Order Nonlinear Optical Chromophores
J . Org. Chem., Vol. 64, No. 12, 1999 4291
Sch em e 1
Sch em e 2
Sch em e 3
Bromination of the available para position in the
triarylamine ring using N-bromosuccinimide in DMF
provided the brominated triarylamine 14. Bromine-
lithium exchange and the subsequent treatment of the
organolithium intermediate with DMF afforded the tri-
arylamine carboxaldehyde 4 in 91% yield as depicted
below.
The alkoxy-functionalized triarylaminecarboxaldehyde
5 was synthesized from the triarylamine 15, which was
assembled in 84% yield from m-anisidine and 8 under
palladium catalysis conditions. The methoxy-substituted
triarylamine 15 was converted to the phenol 16 by
reaction with BBr3 in 66% yield. Treatment of 16 with
monoprotected pentane-1,5-diol 17 under Mitsunobu
reaction conditions affords the product 18. The synthetic
sequence is shown in Scheme 3.
forded the triarylamine carboxaldehyde 5 in 14% overall
yield from 16.22
Bromination of the open para position in the triaryl-
amine ring in 18 using N-bromosuccinimide in DMF
provided the brominated triarylamine 19 in low yield.
Bromine-lithium exchange and the subsequent treat-
ment of the organolithium intermediate with DMF af-
(21) We also attempted to synthesize 13 directly from 11 by treating
the lithiated intermediate with the TBS ether of 6-bromo-1-hexanol.
However, the product had an inseparable impurity that was carried
over from the preparation of the TBS ether of 6-bromo-1-hexanol. The
origin of the impurity is ascribed to an inseparable impurity in the
commercially available starting material.
For the synthesis of 4-hexylthiophene-2-methylene-
triphenylphosphonium chloride (6), we utilized the com-

4292 J . Org. Chem., Vol. 64, No. 12, 1999
Thayumanavan et al.
Sch em e 4
Sch em e 5
afforded the corresponding tricyanovinyl-substituted chro-
mophores. Deprotection of the TBS ether at this juncture,
using acetic acid, afforded the hydroxy-functionalized
tricyanovinylated chromophores 26-28.25 When we at-
tempted to synthesize these chromophores by heating
tetracyanoethylene in DMF with 23, the product 26 was
directly obtained in only 12% yield. In all these reactions,
the chromophores were obtained exclusively as the trans
isomer after the installation of the tricyanovinyl moiety
in the structure. This result is attributed to the strength
of the tricyanovinyl group as an acceptor that favors
significant contribution from the charge-transfer struc-
ture. This reduces the double-bond character of the
formal CdC bond, thus lowering the barrier for isomer-
ization to the thermodynamically more stable trans
isomer (Scheme 5).
mercially available 4-bromothiophene-2-carboxaldehyde
(20) as the starting material. Reduction of the aldehyde
to the corresponding alcohol followed by protection of the
hydroxy group provided the 4-bromothiophenemethylene
ether (21). At this juncture, the hexyl group was installed
by a nickel-catalyzed coupling reaction to afford 22.23 The
methylene ether was then converted to the phosphonium
salt 6 through the corresponding alcohol and chloride.
The synthetic sequence is outlined in Scheme 4.24
Treatment of the aldehydes 3-5 with the phosphonium
salt 6 under Wittig reaction conditions using sodium
ethoxide as the base in ethanol afforded the thiophenyl
stilbene compounds 23-25 as outlined below. The com-
pounds were obtained as a mixture of cis and trans
isomers which were not separated before performing the
next step of the reaction sequence.
We are also interested in NLO chromophores that
absorb in different regions of the visible spectrum (see
Table 1). Therefore, we targeted functionalized chro-
mophores with dicyanovinyl and 3-phenylisoxazolone
groups as acceptor moieties. For this purpose, we treated
(23) Tamo, K. In Comprehensive Organic Synthesis: Selectivity,
Strategy, and Efficiency in Modern Organic Chemistry; Trost, B. M.,
Fleming, I., Eds.; Pergamon Press: New York, 1991; Vol. 3, Chapter
2.2.
Treatment of the compound 23-25 with n-butyl-
lithium, followed by reaction with tetracyanoethylene,
(24) We have used an alternate route to synthesize 6.16 However,
the route reported here is useful since it allows for flexibility to
introduce groups other than the hexyl at the 4-position.
(25) The reason for the low yield in the synthesis of 28 under the
current unoptimized reaction conditions is not clear.
(22) We suggest that the low-yielding step in the reaction is the
bromination reaction. During an independent effort to brominate 15,
we realized that longer reaction times are needed for this type of
substrate.

Synthesis of Second-Order Nonlinear Optical Chromophores
J . Org. Chem., Vol. 64, No. 12, 1999 4293
Ta ble 1. Lin ea r Op tica l Da ta of th e NLO Ch r om op h or es
Sch em e 6
λmax (CH2Cl2)
ꢀ (CH2Cl2)
peak width at
compd
(nm)
(L‚mol-1‚cm-1
)
half-height (cm-1
)
26
28
31
34
32
670
696
539
558
570
38000
45000
41000
41000
41000
3250
3500
3830
4170
3830
the compound 23 with n-butyllithium followed by DMF
to afford the aldehyde product 29 in 80% yield as a 6:4
mixture of trans and cis isomers. This mixture was then
treated with aqueous acetic acid in THF for 12 h at room
temperature and for another 12 h at 45 °C. At this time,
in addition to the deprotection of the hydroxy group there
was a partial isomerization to afford the hydroxy-func-
tionalized aldehyde product 30 in 88% yield as a 9:1
mixture of trans and cis isomers.
Exp er im en ta l Section
1H NMR and 13C NMR spectra were recorded on a 300 MHz
FT NMR spectrometer. 13C NMR spectra were recorded as
proton-decoupled spectra or as attached proton test (APT)
spectra. Fast atom bombardment (FAB) mass spectra were
performed at the University of California, Riverside, or at the
University of California, Los Angeles, Mass Spectrometry
Facilities. The high-resolution mass spectra were obtained
within an uncertainty of +3.2 ppm. Elemental analyses were
performed by the Atlantic Microlab, Inc., Norcross, GA. Where
microanalyses are not reported, the purity of the compounds
was judged to be >95% by NMR. All the reported yields are
isolated yields unless otherwise indicated. Melting points are
reported for all solids isolated and are uncorrected. Toluene
was distilled over Na/Ph2CO ketyl. Aniline was used as
obtained from the commercial sources, and m-anisidine was
distilled under reduced pressure prior to use. All the other
solvents and reagents were used as obtained from the com-
mercial sources unless otherwise mentioned. Flash chroma-
tography was performed with 37-75 µm silica gel. Analytical
thin-layer chromatography was performed on silica gel plates
with F-254 indicator, and the visualization was accomplished
by UV lamp or using the molybdic acid stain mixture.
Synthesis of the compound 9 has been reported elsewhere.19
Syn th esis of th e TBS Eth er 10 fr om 9 by Hyd r obor a -
tion F ollow ed by P r otection . To the neat allyl ether 9 (1.51
g, 3.91 mmol) in a round-bottom flask was added 9-BBN (20.63
mL, 0.50 M solution in THF, 10.32 mmol), and the mixture
was stirred for 24 h at room temperature. At this time, water
(3.0 mL) was added, and the solution was stirred for 5 min.
Then a 3 M aqueous NaOH (3.5 mL) solution followed by 30%
hydrogen peroxide solution (3.5 mL) was added, and the
resulting solution was stirred at 50 °C for 2 h. The solution
was cooled to room temperature and poured into ether (2 ×
100 mL) and water (100 mL). The combined organic layer was
The aldehyde 30 was subjected to Knoevenagel reac-
tion conditions with malononitrile and 3-phenylisox-
azolone to afford the chromophores 31 and 32, respec-
tively. The aldehyde was treated with malononitrile in
methylene chloride for 5 h at room temperature in the
presence of catalytic amount of triethylamine to obtain
the chromophore 31 in 93% yield. However, the reaction
with 3-phenylisoxazolone required 12 h at reflux in
ethanol to afford the chromophore 32 in only 61% yield
(Scheme 6). The chromophore 31 remained as a 9:1
mixture of trans and cis isomers while only the trans
isomer of the chromophore 32 could be isolated.26 Chro-
mophore 34 was also synthesized through a similar route
from 25 through the aldehyde 33.
In summary, we designed and synthesized hydroxy
alkyl-functionalized chromophores with second-order non-
linear optical properties. Since the corresponding un-
functionalized chromophores have been demonstrated to
show high optical nonlinearities, along with enhanced
thermal and photochemical stabilities, we expect these
chromophores to have similar properties associated with
them.16 Work is in progress to study the properties of bulk
electrooptic materials following incorporation of these
chromophores into functionalized high-performance poly-
mers.
(26) This result is attributed to the difference in the strength of the
dicyanovinyl and the 3-phenylisoxazolone acceptor. The stronger
acceptor would have more attenuated bond length alternation and thus
reduce the barrier to isomerization to the thermodynamically more
stable trans isomer.

4294 J . Org. Chem., Vol. 64, No. 12, 1999
Thayumanavan et al.
dried over Na2SO4, filtered, concentrated in vacuo, and purified
by flash column chromatography using 1:1 hexanes/ethyl
acetate mixture as the mobile phase to afford 1.20 g (76%) of
the alcohol product as an yellow oil. 1H NMR (C6D6, 300 MHz)
δ: 7.14-7.01 (m, 8H); 6.92 (d, 4H, J ) 8.0 Hz); 6.81 (t, 1H, J
) 7.1 Hz); 3.59 (bt, 2H); 3.36 (t, 2H, J ) 6.9 Hz); 3.29 (t, 2H,
J ) 5.9 Hz); 2.65 (t, 2H, J ) 6.9 Hz); 2.42 (t, 2H, J ) 7.7 Hz);
2.15 (s, 1H); 1.60 (m, 2H); 1.46 (m, 2H); 1.23 (m, 2H); 0.84 (t,
3H, J ) 7.3 Hz). 13C NMR (CDCl3, 75 MHz) δ: 148.1, 146.2,
145.3, 137.5, 132.7, 129.5, 129.1, 129.0, 124.4, 124.0, 123.3,
121.9, 72.1, 70.2, 62.0, 35.6, 35.0, 33.6, 31.9, 22.4, 14.0.
HRMS: calcd for C27H33NO2 403.2511, found 403.2502.
The alcohol from the last step (1.03 g, 2.55 mmol), imidazole
(0.38 g, 5.6 mmol), and tert-butyldimethylsilyl chloride (0.42
g, 2.8 mmol) were taken in a round-bottom flask with 20 mL
of DMF/dry CH2Cl2 (1:1) and stirred for 90 min at room
temperature. The resultant solution was poured into water
(100 mL) and extracted with methylene chloride (2 × 100 mL).
The combined organic layer was washed with water (4 × 150
mL), dried over Na2SO4, filtered, and concentrated under
reduced pressure. The resultant residue was purified by flash
column chromatography using 9:1 hexanes/ethyl acetate mix-
ture as the mobile phase to obtain 1.15 g (87%) of the product
ture for 10 min. Then, sodium tert-butoxide (19.8 g, 0.206
mmol) and 4-butylaniline (25 mL, 0.16 mol) were added, and
the resulting solution was stirred at 90 °C for 6 h. After the
completion of the reaction was confirmed by thin-layer chro-
matography, 1,4-dibromobenzene (112 g, 0.470 mol) and
sodium tert-butoxide (19.8 g, 0.210 mmol) were added, and the
mixture was stirred for another 12 h. Following workup using
water and ether, the reaction mixture was purified by flash
column chromatography using 30:1 hexanes/ethyl acetate
mixture as the mobile phase to afford 45.2 g (75%) of the
product as a colorless oil. 1H NMR (CD2Cl2, 300 MHz) δ: 7.35-
7.22 (m, 4H); 7.12-6.98 (m, 7H); 6.91 (d, 2H, J ) 7.0 Hz); 2.59
(t, 2H, J ) 7.7 Hz); 1.61 (m, 2H); 1.40 (m, 2H); 0.95 (t, 3H, J
) 7.3 Hz); 13C NMR (CD2Cl2, 75 MHz) δ: 147.9, 147.7, 145.2,
139.0, 132.3, 129.7, 129.6, 125.4, 124.8, 124.4, 123.3, 114.3,
35.4, 34.1, 22.8, 14.2.
Syn th esis of 12 fr om 11. To a solution of 11 (2.53 g, 6.64
mmol) in THF (50 mL) at -78 °C was added tert-butyllithium
(8.20 mL, 1.70 M solution in pentane, 13.9 mmol), and the
resultant mixture was stirred at this temperature for 15 min.
Then 6-bromo-1-hexene (over 2 equivalent) was added to this
solution, and the resultant mixture was stirred at -78 °C for
1 h and at ambient temperature for 3 h. Following workup
using water and ether, flash column chromatography with
hexanes as the mobile phase provided 1.86 g (73%) of 12 as a
1
10 as a yellow oil. H NMR (C6D6, 300 MHz) δ: 7.17 (bd, 6H,
J ) 8.3 Hz); 7.06 (d, 2H, J ) 7.3 Hz); 7.01 (d, 2H, J ) 7.2 Hz);
6.95 (t, 2H); 6.81 (t, 1H, J ) 7.2 Hz); 3.66 (t, 2H, J ) 6.1 Hz);
3.45 (t, 2H, J ) 7.0 Hz); 3.41 (t, 2H, J ) 6.0 Hz); 2.74 (t, 2H,
J ) 6.5 Hz); 2.42 (t, 2H, J ) 7.7 Hz); 1.75 (m, 2H); 1.47 (m,
2H); 1.23 (m, 2H); 0.97 (s, 9H); 0.84 (t, 3H, J ) 7.3 Hz); 0.05
(s, 6H). 13C NMR (CDCl3, 75 MHz) δ: 148.1, 146.1, 145.4,
137.5, 133.1, 129.6, 129.1, 129.0, 124.4, 124.0, 123.3, 121.9,
71.9, 67.5, 60.0, 35.7, 35.0, 33.7, 32.9, 26.0, 22.4, 18.3, 14.0,
-5.3. HRMS: calcd for C33H47NO2Si 517.3376, found: 517.3371.
Syn th esis of th e Tr ia r yla m in e 3 fr om 10. To a solution
of NBS (2.69 g, 15.09 mmol) in DMF (15 mL) was added a
solution of 10 (7.82 g, 15.1 mmol) in DMF (15 mL), and the
resulting solution was stirred overnight at ambient temper-
ature. The reaction mixture was then poured into water (100
mL) and ether (2 × 150 mL). The combined ether layer was
washed with water (4×), dried over Na2SO4, decanted, con-
centrated in vacuo, and purified by flash column chromatog-
raphy using 19:1 hexanes/ethyl acetate mixture as the mobile
phase to afford 8.50 g (94%) of bromo compound as a yellow
oil. This product was carried over to the next step without
further characterization.
1
colorless oil. H NMR (CD2Cl2, 300 MHz) δ: 7.20 (t, 2H, J )
8.3 Hz); 7.07 (d, 4H, J ) 8.1 Hz); 6.94 (bm, 7H); 5.80 (m, 1H);
4.99 (d, 1H, J ) 17.1 Hz); 4.90 (d, 1H, J ) 10.1 Hz); 2.56 (t,
4H, J ) 7.7 Hz); 2.08 (m, 2H); 1.63-1.35 (m, 8H); 0.93 (t, 3H,
J ) 7.4 Hz). 13C NMR (CD2Cl2, 75 MHz) δ: 148.8, 146.1, 146.0,
139.4, 138.1, 137.8, 129.6, 129.5, 124.8, 124.7, 123.5, 122.2,
114.1, 35.6, 35.4, 34.2, 34.1, 31.5, 29.1, 22.9, 14.2. One
overlapping aromatic 13C signal is assumed. HRMS: calcd for
C28H33N 388.2613, found 388.2615.
Syn th esis of 13 fr om 12. To the neat triarylamine 12 (1.85
g, 4.82 mmol) in a round-bottomed flask was added 9-BBN
(24.10 mL, 0.50 M solution in THF, 12.05 mmol), and the
resulting solution was stirred for 24 h at room temperature.
At this time, water (5 mL) was added, and the solution was
stirred for 5 min. Then to this solution was added 3 M aqueous
NaOH (6 mL) followed by 30% hydrogen peroxide solution (6
mL), and the resulting mixture was stirred at 50 °C for 2 h.
The solution was cooled to room temperature and poured into
ether (2 × 100 mL) and water (100 mL). The combined organic
layer was dried over Na2SO4, concentrated in vacuo, and
purified by flash column chromatography using 1:1 hexanes/
ethyl acetate mixture as the mobile phase to afford 1.74 g
To a solution of the TBS ether from the previous step (8.40
g, 14.1 mmol) in THF (150 mL) at -78 °C was added t-BuLi
(20.4 mL, 1.45 M solution in pentane, 29.6 mmol), and the
resultant mixture was stirred for 10 min at this temperature.
To this solution was added DMF (3.30 mL, 42.2 mmol), and
the resultant mixture was stirred at -78 °C for 15 min and at
ambient temperature for over 2 h. The solution was poured
into water (300 mL) and extracted with ether (2 × 250 mL).
The combined ether layer was washed with water (300 mL),
dried over MgSO4, filtered, concentrated in vacuo, and purified
by flash column chromatography using 9:1 hexanes/ethyl
acetate mixture as the mobile phase to afford 6.14 g (80%) of
the product 3 as a viscous oil. 1H NMR (acetone-d6, 300 MHz)
δ: 9.82 (s, 1H); 7.71 (d, 2H, J ) 8.7 Hz); 7.32 (d, 2H, J ) 8.3
Hz); 7.27 (d, 2H, J ) 8.2 Hz); 7.15 (d, 4H, J ) 8.1 Hz); 6.92 (d,
2H, J ) 8.7 Hz); 3.72 (t, 2H, J ) 6.2 Hz); 3.66 (t, 2H, J ) 6.8
Hz); 3.55 (t, 2H, J ) 6.1 Hz); 2.89 (t, 2H, J ) 6.8 Hz); 2.65 (t,
2H, J ) 7.6 Hz); 1.75 (m, 2H); 1.64 (m, 2H); 1.39 (m, 2H); 0.96
(t, 3H, J ) 7.4 Hz); 0.91 (s, 9H); 0.06 (s, 6H). 13C NMR (acetone-
d6, 75 MHz) δ: 190.4, 154.3, 145.0, 144.6, 141.0, 137.7, 131.8,
131.2, 130.6, 129.7, 127.4, 127.2, 118.7, 72.1, 67.7, 60.4, 36.4,
35.6, 34.4, 33.8, 26.2, 23.0, 18.9, 14.2, -5.2. HRMS: Calcd for
1
(90%) of the product as an oil. H NMR (CD2Cl2, 300 MHz) δ:
7.20 (t, 2H, J ) 7.8 Hz); 7.05 (d, 4H, J ) 8.2 Hz); 6.97 (bm,
7H); 3.60 (m, 2H); 2.55 (t, 4H, J ) 7.7 Hz); 1.63-1.53 (m, 6H);
1.42-1.32 (m, 6H); 1.22 (bm, 1H); 0.93 (t, 3H, J ) 7.3 Hz). 13
C
NMR (CD2Cl2, 75 MHz) δ: 148.8, 146.1, 146.0, 138.0, 137.9,
129.5, 129.4, 124.8, 124.7, 123.4, 122.2, 63.2, 35.7, 35.4, 34.7,
33.3, 32.0, 29.6, 26.1, 22.9, 14.2. One overlapping aromatic 13
C
signal is assumed. HRMS: calcd for C28H35NO 401.2719, found
401.2715.
The alcohol from the last step (1.61 g, 4.01 mmol), imidazole
(0.55 g, 8.0 mmol), and tert-butyldimethylsilyl chloride (0.73
g, 4.8 mmol) were taken in a round-bottomed flask with 20
mL of DMF/dry CH2Cl2 (1:1) and stirred for 90 min at room
temperature. The resultant solution was poured into water
(100 mL) and extracted with methylene chloride (2 × 100 mL).
The combined organic layer was washed with water (4 × 150
mL), dried over Na2SO4, and concentrated under reduced
pressure. The resultant residue was purified by flash column
chromatography using 9:1 hexanes/ethyl acetate mixture as
the mobile phase to obtain 1.98 g (96%) of the product 13 as a
C
34H47NO3Si 545.3325, found 545.3311.
1
yellow oil. H NMR (CD2Cl2, 300 MHz) δ: 7.20 (t, 2H, J ) 7.8
Syn th esis of 11 fr om 4-Bu tyla n ilin e, Br om oben zen e,
Hz); 7.06 (d, 4H, J ) 8.3 Hz); 6.94 (bm, 7H); 3.60 (t, 2H, J )
6.4 Hz); 2.55 (t, 4H, J ) 7.6 Hz); 1.63-1.33 (m, 12H); 0.93 (t,
3H, J ) 7.3 Hz); 0.88 (s, 9H); 0.04 (s, 6H). 13C NMR (CD2Cl2,
75 MHz) δ: 148.8, 146.1, 138.1, 138.0, 129.6, 129.4, 124.8,
123.4, 122.2, 63.6, 35.7, 35.4, 34.2, 33.3, 32.0, 29.6, 26.2, 26.1,
22.9, 18.7, 14.2, -5.1. Three overlapping aromatic 13C signals
a n d 1,4-Dib r om ob en zen e. To a solution of tris(dibenzyli-
deneacetone)dipalladium (Pd2(dba)3) (2.17 g, 2.38 mmol) and
1,1′-bis(diphenylphosphino)ferrocene (DPPF) (1.98 g, 3.56
mmol) in toluene (400 mL) under nitrogen atmosphere was
added bromobenzene (16.7 mL, 0.160 mol) at room tempera-
ture, and the resultant mixture was stirred at that tempera-

Synthesis of Second-Order Nonlinear Optical Chromophores
J . Org. Chem., Vol. 64, No. 12, 1999 4295
are assumed due to the similarities in the aliphatic side chains.
HRMS: calcd for C34H49NOS 515.3583, found 515.3576.
Syn th esis of th e Tr ia r yla m in e 4 fr om 13. The open para
position of the aromatic ring was brominated in 87% yield
using the same procedure adapted for the bromination of 10.
1H NMR (CD2Cl2, 300 MHz) δ: 7.27 (d, 2H, J ) 8.8 Hz); 7.07
(d, 4H, J ) 8.3 Hz); 6.96 (d, 4H, J ) 8.3 Hz); 6.85 (d, 2H, J )
8.8 Hz); 3.59 (t, 2H, J ) 6.4 Hz); 2.56 (t, 4H, J ) 7.5 Hz); 1.60-
1.32 (m, 12H); 0.93 (t, 3H, J ) 7.4 Hz); 0.88 (s, 9H); 0.03 (s,
6H). 13C NMR (CD2Cl2, 75 MHz) δ: 148.1, 145.5, 138.7, 132.3,
129.7, 125.1, 124.2, 113.8, 63.6, 35.7, 35.4, 34.2, 33.3, 32.0, 29.6,
2H), 0.89 (s, 9H), 0.04 (s, 6H). 13C NMR (CD2Cl2, 75 MHz) δ:
63.6, 62.9, 33.1, 33.0, 26.3, 22.6, 18.7, -5.1.
Syn th esis of 5 fr om 16. To a solution of 16 (0.96 g, 4.3
mmol), triphenylphosphine (1.39 g, 5.32 mmol), and 5-tert-
butyldimethylsilyloxypentanol (17) (0.77 g, 3.5 mmol) in THF
(50 mL) at 0 °C was added diethyl azodicarboxylate (DEAD)
(0.74 g, 4.3 mmol) dropwise with stirring. The resultant
solution was allowed to stir for 18 h while warming to room
temperature. Separation of the reaction mixture between
water and ether layers and concentration of the organic layer
in vacuo followed by purification by flash column chromatog-
raphy provided 0.83 g of a colorless oil that was a mixture of
product and triphenylphosphine. Since this mixture could not
be easily separated to afford the pure product 18, this mixture
was taken to the next step without further purification.
The mixture from the previous reaction (0.78 g) in DMF (2
mL) was mixed with a solution of N-bromosuccinimide (0.33
g, 1.8 mmol) in DMF (3 mL), and the resultant mixture was
stirred at room temperature overnight. The reaction mixture
was separated between ether and water, and then the organic
layer was washed with water. Concentration of the organic
layer followed by purification using silica gel flash column
chromatography afforded 0.51 g of colorless oil. This reaction
mixture contained small amounts of triphenylphosphine and
the product from the previous step along with the desired
brominated product. This mixture was taken to the next step
without further purification.
26.2, 26.1, 22.9, 18.7, 14.2, -5.1. HRMS: calcd for C34H48
NOBrSi 593.2689, found 593.2691.
-
The procedure for bromine lithium exchange used in the
synthesis of 3 was adapted here to afford 4 as a viscous oil in
1
91% yield. H NMR (CD2Cl2, 300 MHz) δ: 9.74 (s, 1H); 7.61
(d, 2H, J ) 8.7 Hz); 7.17 (d, 4H, J ) 8.3 Hz); 7.08 (d, 4H, J )
8.3 Hz); 6.91 (d, 2H, J ) 8.7 Hz); 3.59 (t, 2H, J ) 6.4 Hz); 2.60
(t, 4H, J ) 7.6 Hz); 1.65-1.32 (m, 12H); 0.94 (t, 3H, J ) 7.3
Hz); 0.88 (s, 9H); 0.03 (s, 6H). 13C NMR (CD2Cl2, 75 MHz) δ:
190.3, 154.1, 144.1, 140.7, 131.4, 130.1, 128.9, 126.9, 118.4,
63.5, 35.8, 35.5, 34.1, 33.2, 31.9, 29.5, 26.2, 26.1, 22.8, 18.6,
14.1, -2.6. HRMS: calcd for C35H49NO2Si 543.3533, found
543.3539.
Syn th esis of 4′,4′′-Dibu tyl-3-m eth oxytr ip h en yla m in e
(15). To a solution of Pd2(dba)3 (0.90 g, 0.98 mmol) and DPPF
(0.81 g, 1.5 mmol) in toluene (120 mL) under nitrogen
atmosphere was added 1-bromo-4-butylbenzene (20.90 g, 97.89
mmol) at room temperature, and the resultant mixture was
stirred at that temperature for 10 min. Then, sodium tert-
butoxide (10.69 g, 110 mmol) and m-anisidine (5.48 g, 44.5
mmol) were added to this solution and stirred at 90 °C for 24
h. Following workup, the reaction mixture was purified by
flash column chromatography using 20:1 hexanes/ethyl acetate
mixture as the mobile phase to afford 14.4 g (84%) of 15 as an
oil. 1H NMR (CD2Cl2, 300 MHz) δ: 7.19-7.10 (bt, 5H); 7.05
(d, 4H, J ) 8.4 Hz); 6.65-6.50 (m, 3H); 3.75 (s, 3H); 2.64 (t,
4H, J ) 7.7 Hz); 1.66 (m, 4H); 1.46 (m, 4H); 1.02 (t, 6H, J )
7.3 Hz). 13C NMR (CD2Cl2, 75 MHz) δ: 160.8, 150.0, 145.8,
138.1, 129.9, 129.5, 124.9, 115.5, 109.0, 107.1, 55.4, 35.4, 34.2,
To a solution of the crude product from the previous reaction
(0.48 g) in THF (10 mL) at -78 °C under nitrogen atmosphere
was added t-BuLi (1.37 mL, 1.45 M solution in pentane, 1.99
mmol), and the resultant solution was stirred at this temper-
ature for 10 min. Then, DMF (0.22 mL, 2.9 mmol) was added
to this solution and the resultant mixture was stirred at -78
°C for 1 h and at ambient temperature for 3 h. Separation of
the reaction mixture between water and ether and concentra-
tion of the organic layer in vacuo followed by purification by
flash column chromatography using 10:1 hexanes/ethyl acetate
mixture as the mobile phase afforded 0.20 g of the product 5
1
as a yellow oil. The overall yield of the reaction was 14%. H
NMR (CD2Cl2, 300 MHz) δ: 10.3 (s, 1H); 7.63 (d, 1H, J ) 8.7
Hz); 7.23 (d, 4H, J ) 8.2 Hz); 7.15 (d, 4H, J ) 8.3 Hz); 6.48 (d,
1H, J ) 8.7 Hz); 6.44 (s, 1H); 3.87 (t, 2H, J ) 6.2 Hz); 3.68 (t,
2H, J ) 6.0 Hz); 2.67 (t, 4H, J ) 7.6 Hz); 1.81-1.41 (m, 14H);
1.01 (t, 6H, J ) 7.3 Hz); 0.96 (s, 9H); 0.11 (s, 6H). 13C NMR
(CD2Cl2, 75 MHz) δ: 187.5, 163.2, 155.5, 144.0, 140.6, 129.9,
129.3, 126.9, 118.0, 111.3, 101.6, 68.5, 63.3, 35.5, 34.0, 32.9,
22.8, 14.2. HRMS: calcd for
387.2549.
C27H33NO 387.2562, found
Syn th esis of 16 fr om 15. To the round-bottom flask
containing 15 (31.90 g, 82.31 mmol) in CH2Cl2 (400 mL) under
nitrogen atmosphere at -78 °C was added BBr3 (8.97 mL, 98.8
mmol). The resultant solution was stirred at -78 °C for 5 min,
the cold bath was removed, and the solution was stirred for 3
h at ambient temperature. The reaction mixture was then
poured in 150 mL of ice-water slush and stirred for another
90 min. The solution was poured in a separatory funnel and
separated between methylene chloride and water. The organic
layer was concentrated in vacuo and purified by flash column
chromatography using 10:1 hexanes/ethyl acetate mixture as
the mobile phase to afford 20.4 g (66%) of the product 16 as
an oil. 1H NMR (CD2Cl2, 300 MHz) δ: 7.13 (d, 4H, J ) 8.4
Hz); 7.08 (d, 1H, J ) 8.2 Hz); 7.03 (d, 4H, J ) 8.4 Hz); 6.58
(dd, 1H, J ) 1.4 Hz; J ) 8.1 Hz); 6.48 (t, 1H, J ) 1.4 Hz); 6.43
(dd, 1H, J ) 2.0 Hz, J ) 7.5 Hz); 4.80 (s, 1H); 2.62 (t, 4H, J )
1.2 Hz); 1.64 (m, 4H, J ) 8.0 Hz); 1.43 (m, 4H, J ) 7.6 Hz);
0.99 (t, 6H, J )7.3 Hz). 13C NMR (CD2Cl2, 75 MHz) δ: 156.7,
150.2, 145.6, 138.4, 130.1, 129.5, 125.2, 114.9, 109.2, 108.5,
35.3, 34.1, 22.8, 14.1. HRMS: calcd for C26H31NO 373.2421,
found 373.2406.
Syn th esis of 17. To a solution of pentane-1,5-diol (47.7 g,
0.460 mol) in DMF (800 mL) were added imidazole (23.4 g,
0.340 mol) and tert-butyldimethylsilyl chloride (34.5 g, 0.230
mol), and the resultant solution was stirred at ambient
temperature for 2 h. The reaction mixture was partitioned
between ether and water and the organic layer was washed
with water (4×). The resultant organic mixture was concen-
trated in vacuo. The reaction mixture was purified by flash
column chromatography using 9:1 followed by 3:1 hexanes/
ethyl acetate mixture as the mobile phases to afford 31.11 g
(62%) of 17 as a colorless oil. 1H NMR (CDCl3, 300 MHz) δ:
3.61 (t, 4H, J ) 6.33 Hz), 2.09 (br, 1H), 1.52 (m, 4H), 1.39 (m,
29.2, 29.0, 26.1, 22.8, 18.6, 14.2, -5.2. HRMS: calcd for C38H56
NO3Si 602.4030, found 602.4026.
-
Syn th esis of 21 fr om 20. To a solution of the commercially
available aldehyde 20 (49 g, 0.26 mol) in absolute ethanol (500
mL) at room temperature was added sodium borohydride (27.4
g, 0.720 mol), and the resultant solution was stirred for 4 h at
ambient temperature. The reaction mixture was separated
between CH2Cl2 and water, and the organic layer was con-
centrated in vacuo. The resultant product mixture was passed
through a plug of silica gel and taken to the next step after
drying in vacuo without further purification or characteriza-
tion.
The product from the previous reaction was dissolved in a
mixture of methylene chloride (200 mL) and DMF (300 mL)
along with imidazole (34.9 g, 0.510 mol) and tert-butyldi-
methylsilyl chloride (42.5 g, 0.280 mol). The resultant mixture
was stirred at room temperature for 90 min and then sepa-
rated between methylene chloride and water. The organic layer
was washed with water (4×), concentrated in vacuo, and
passed through a silica gel plug to afford 72.1 g (92%) of the
product 21 as a colorless oil. 1H NMR (CD2Cl2, 300 MHz) δ:
7.16 (s, 1H); 6.85 (s, 1H); 4.84 (s, 2H); 0.94 (s, 9H); 0.12 (s,
6H). 13C NMR (CD2Cl2, 75 MHz) δ: 147.5, 126.1, 122.1, 109.1,
60.8, 28.0, 18.6, -5.2.
Syn th esis of 22 fr om 21. A cold solution (-10 °C) of
hexylmagnesium bromide (141 mL, 2 M solution in THF, 0.282
mol) was added to a cold round-bottomed flask (-10 °C)
containing 1,3-bis(diphenylphosphino)propanedichloronickel
(1.53 g, 2.82 mmol), and the resultant solution was stirred at

4296 J . Org. Chem., Vol. 64, No. 12, 1999
Thayumanavan et al.
this temperature for 10 min. Then the bromothiophene
compound 21 (72.1 g, 0.240 mol) was added dropwise over a
period of 1 h to this reaction mixture. The resultant solution
was stirred for 24 h while the solution warmed to room
temperature. The worked-up reaction mixture was purified by
flash column chromatography using 30:1 hexanes/ethyl acetate
mixture as the mobile phase to afford 30.6 g (42%) of the
product 22 as a colorless oil. 1H NMR (CD2Cl2, 300 MHz) δ:
6.81 (s, 1H); 6.76 (s, 1H); 4.79 (s, 2H); 2.54 (t, 2H, J ) 7.4 Hz);
1.55 (m, 2H); 1.30 (bs, 6H); 0.90 (bm, 12H); 0.09 (s, 6H). 13C
NMR (CD2Cl2, 75 MHz) δ: 145.2, 143.3, 125.8, 119.4, 61.1,
32.1, 30.9, 30.8, 29.4, 26.0, 23.0, 19.2, 14.3, -5.2.
column chromatography was performed to afford the chro-
mophore 26, 27, or 28.
Ch r om op h or e 26. Characterizing data for the TBS pro-
tected precursor follow: 1H NMR (CD2Cl2, 300 MHz) δ: 7.36
(d, 2H, J ) 8.7 Hz); 7.26-7.04 (m, 11H); 6.93 (d, 2H, J ) 8.7
Hz); 3.67 (t, 2H, J ) 6.2 Hz); 3.60 (t, 2H, J ) 6.9 Hz); 3.51 (t,
2H, J ) 6.3 Hz); 3.04 (t, 2H, J ) 7.6 Hz); 2.84 (t, 2H, J ) 6.8
Hz); 2.60 (t, 2H, J ) 7.6 Hz); 1.76-1.32 (m, 14H); 0.95-0.90
(m, 6H); 0.89 (s, 9H); 0.04 (s, 6H). 13C NMR (CD2Cl2, 75 MHz)
δ: 158.6, 155.4, 150.5, 145.0, 144.4, 139.9, 137.4, 136.1, 130.7,
130.3, 130.1, 129.8, 129.1, 127.7, 126.4, 126.2, 125.9, 120.6,
116.6, 113.9, 71.9, 67.7, 60.2, 36.0, 35.4, 34.1, 33.3, 31.9, 31.6,
31.2, 29.5, 26.1, 22.9, 22.8, 14.2, 14.1, 9.0, -5.3. Overlap of
three aromatic 13C signals are assumed. The overlapping peaks
can be identified by comparison with the 13C NMR spectrum
Syn th esis of 6 fr om 22. To a solution of 22 (27.4 g, 87.7
mmol) in THF (100 mL) was added tetrabutylammonium
fluoride (105 mL, 1 M solution in THF, 105 mmol), and the
resulting solution was stirred at ambient temperature for 24
h. Following workup with water and ether, the mixture was
purified by flash column chromatography using 10:1 hexanes/
ethyl acetate mixture as the mobile phase to afford 10.5 g
of 26. HRMS: calcd for
C50H62N4O2SSi 810.4363, found
810.4380.
Characterizing data for the chromophore 26 follow. Mp:
1
100-103 °C. H NMR (CD2Cl2, 300 MHz) δ: 7.37 (d, 2H, J )
1
8.7 Hz); 7.30-7.03 (m, 11H); 6.93 (d, 2H, J ) 8.7 Hz); 3.65 (m,
6H); 3.04 (t, 2H, J ) 7.7 Hz); 2.85 (t, 2H, J ) 6.8 Hz); 2.60 (t,
2H, J ) 7.7 Hz); 2.04 (t, 1H, J ) 5.5 Hz); 1.81-1.32 (m, 14H);
0.90 (m, 6H). 13C NMR (CD2Cl2, 75 MHz) δ: 158.6, 155.4,
150.4, 145.1, 144.4, 139.9, 137.4, 135.7, 130.7, 130.6, 130.5,
130.3, 130.0, 129.8, 129.1, 127.7, 126.6, 126.4, 126.2, 125.9,
120.6, 116.6, 113.9, 72.1, 70.4, 62.0, 36.0, 35.4, 34.0, 32.5, 31.8,
31.6, 31.1, 29.4, 22.9, 22.8, 14.2, 14.1. HRMS: calcd for
(60%) of the alcohol product was isolated as a colorless oil. H
NMR (CD2Cl2, 300 MHz) δ: 6.86 (s, 1H); 6.85 (s, 1H); 4.73 (d,
2H, J ) 5.7 Hz); 2.56 (t, 2H, J ) 7.6 Hz); 2.0 (bs, 1H); 1.59
(bm, 2H); 1.31 (bm, 6H); 0.89 (t, 3H, J ) 6.1 Hz). 13C NMR
(CD2Cl2, 75 MHz) δ: 144.3, 143.6, 127.1, 120.2, 60.3, 32.0, 30.8,
30.7, 29.3, 23.0, 14.2.
The alcohol product from the previous step (8.21 g, 41.4
mmol) was cooled to -78 °C, and concentrated hydrochloric
acid (25.0 mL, 298 mmol) was added slowly to result in an
inhomogeneous mixture. After 15 min, this mixture was
warmed to room temperature and stirred for 4 h. The reaction
mixture was separated between water and ether. The resultant
organic layer was dried over anhydrous sodium sulfate,
decanted, and concentrated in vacuo. The resultant product
was characterized by thin-layer chromatography and carried
over to the next step without further characterization.
C
44H48N4O2S 696.3498, found 696.3507.
Ch r om op h or e 27. Characterizing data for the TBS-
protected precursor follow. 1H NMR (CD2Cl2, 300 MHz) δ: 7.36
(d, 2H, J ) 8.8 Hz); 7.22 (d, 1H, J ) 16.0 Hz); 7.13 (d, 4H, J
) 8.3 Hz); 7.08-7.03 (bt, 6H); 6.91 (t, 2H, J ) 8.8 Hz); 3.60 (t,
2H, J ) 6.3 Hz); 3.04 (t, 2H, J ) 7.7 Hz); 2.59(t, 4H, J ) 7.7
Hz); 1.64-1.32 (m, 20H); 0.94 (t, 3H, J ) 7.3 Hz); 0.88 (bs,
12H); 0.04 (s, 6H). 13C NMR (CD2Cl2, 75 MHz) δ: 158.5, 155.5,
150.8, 144.6, 144.5, 139.9, 137.6, 130.7, 130.1, 129.9, 129.3,
127.5, 126.3, 126.0, 120.4, 116.6, 113.9, 113.8, 68.2, 63.5, 35.8,
35.5, 34.1, 33.3, 32.1, 32.0, 31.7, 31.3, 29.6, 26.3, 26.2, 23.0,
22.9, 18.7, 14.3, 14.2, -5.0. Overlap of one aromatic 13C signal
is assumed. The overlapping peak can be identified by com-
parison with the 13C NMR spectrum of 27. HRMS: calcd for
To a solution of the product from the above reaction in
xylene (50 mL) was added triphenylphosphine (11.94 g, 45.50
mmol), and the resultant mixture was heated to reflux
overnight. Then, the reaction mixture was allowed to cool to
room temperature and filtered. The solid obtained was washed
with benzene and dried in vacuo to afford 15.9 g (80%) of 6 as
C
51H64N4OSSi 808.4570, found 808.4591.
1
a white solid. Mp: 220-222 °C. H NMR (CD2Cl2, 300 MHz)
Characterizing data for the chromophore 27 follow. Mp: 95-
δ: 7.87-7.63 (m, 15H); 6.78 (s, 1H); 6.77 (s, 1H); 5.70 (d, 2H,
J ) 13.4 Hz); 2.44 (t, 2H, J ) 7.6 Hz); 1.42 (bm, 2H); 1.27
(bm, 6H); 0.87 (bt, 3H). 13C NMR (CD2Cl2, 75 MHz) δ: 143.5
(d, J ) 3.4 Hz); 134.9 (d, J ) 2.4 Hz); 134.4 (d, J ) 9.9 Hz);
132.7 (d, J ) 7.9 Hz); 130.0 (d, J ) 12.5 Hz); 127.9 (d, J )
10.2 Hz); 121.4 (d, J ) 4.5 Hz); 118.0 (d, J ) 85.8 Hz); 31.0 (d,
J ) 86.0 Hz); 30.1, 28.8, 26.9, 26.3, 22.6, 13.9. 31P NMR (CD2-
Cl2, 400 MHz) δ: 22.90.
97 °C. 1H NMR (CD2Cl2, 300 MHz) δ: 7.40 (d, 2H, J ) 8.8
Hz); 7.26 (d, 1H, J ) 16.0 Hz); 7.17 (d, 4H, J ) 8.3 Hz); 7.12-
7.06 (t, 6H); 6.95 (d, 2H, J ) 8.8 Hz); 3.63 (q, 2H, J ) 6.3 Hz);
3.08 (t, 2H, J ) 7.7 Hz); 2.63 (t, 4H, J ) 7.5 Hz); 1.75-1.21
(m, 21H); 0.97 (t, 3H, J ) 7.3 Hz); 0.91 (t, 3H). 13C NMR (CD2-
Cl2, 75 MHz) δ: 158.6, 155.5, 150.7, 144.5, 144.4, 139.9, 139.8,
137.5, 130.7, 130.0, 129.8, 129.2, 127.5, 126.2, 125.9, 120.4,
116.6, 113.9, 113.8, 63.1, 35.7, 35.5, 34.0, 33.2, 31.9, 31.8, 31.6,
31.2, 29.5, 29.4, 26.0, 22.9, 22.8, 14.2, 14.1. HRMS: calcd for
C45H50N4OS 694.3705, found 694.3764. Anal. Calcd for C45H50N4-
OS: C, 77.77; H, 7.25; N, 8.06, found C, 77.70; H, 7.28; N, 7.97.
Ch r om op h or e 28. Characterizing data for the TBS-
protected precursor follow. 1H NMR (CD2Cl2, 300 MHz) δ: 7.50
(d, 1H, J ) 16.0 Hz); 7.30 (d, 1H, J ) 8.3 Hz); 7.23 (d, 1H, J
) 16.0 Hz); 7.14 (d, 4H, J ) 8.3 Hz); 7.08 (m, 5H); 6.48 (m,
2H); 3.83 (t, 2H, J ) 6.4 Hz); 3.61 (t, 2H, J ) 6.7 Hz); 3.04 (t,
2H, J ) 6.7 Hz); 2.59 (t, 4H, J ) 7.6 Hz); 1.81-1.26 (m, 22H);
0.94 (m, 9H); 0.86 (s, 9H); 0.02 (s, 6H). 13C NMR (CD2Cl2, 75
MHz) δ: 159.4, 158.6, 157.3, 152.3, 144.5, 140.1, 134.0, 130.0,
129.9, 129.6, 129.3, 126.5, 126.0, 125.7, 117.1, 117.0, 114.2,
114.1, 114.0, 113.1, 103.8, 68.8, 63.4, 35.5, 34.1, 33.0, 32.0, 31.7,
31.3, 29.6, 29.3, 26.2, 23.0, 22.9, 22.8, 18.6, 14.3, 14.2, -5.1.
HRMS: calcd for C54H70N4O2SSi 866.4989, found 866.4979.
Characterizing data for chromophore 28 follow. Mp: 112-
Gen er a l P r oced u r e for th e Wittig Rea ction of th e
Ald eh yd es 3, 4, or 5 w ith 6. To a 1:1 mixture of the aldehyde
and the phosphonium salt 6 in ethanol was added a freshly
prepared solution of sodium ethoxide (1.5 equiv) in ethanol.
The resultant mixture was stirred at reflux for 5 h. Following
workup with ether and water, the product 23, 24, or 25 was
obtained as a mixture of trans and cis isomers. These products
were carried over to the next step without further character-
ization.
Gen er a l P r oced u r e for th e Syn th esis of th e Ch r o-
m op h or es 26-28 fr om 23-25. To a solution of the styryl
thiophene 23, 24, or 25 in THF at -78 °C was added
n-butyllithium (1.2 equiv), and the resultant mixture was
stirred at -78 °C for 45 min. Then tetracyanoethylene was
added as a solid to this solution, and the mixture was stirred
for 1 h at -78 °C and for 3 h at ambient temperature.
Following workup with ethyl acetate and water, flash column
chromatography was performed to afford the TBS-protected
chromophores.
1
114 °C. H NMR (CD2Cl2, 300 MHz) δ: 7.53 (d, 1H, J ) 16.0
Hz); 7.32 (d, 1H, J ) 8.6 Hz); 7.21 (d, 1H, J ) 16.0 Hz); 7.14
(d, 4H, J ) 8.3 Hz); 7.05 (m, 5H); 6.45 (m, 2H); 3.82 (t, 2H, J
) 6.1 Hz); 3.61 (q, 2H, J ) 5.6 Hz); 3.04 (t, 2H, J ) 7.8 Hz);
To a solution of the TBS-protected chromophore from the
above reaction in THF (3 mL for 1 mmol substrate) were added
acetic acid (10 mL) and water (3 mL). The resultant mixture
was stirred at ambient temperature for 12 h and at 45 °C for
12 h. Following workup with ethyl acetate and water, flash
2.59 (t, 4H, J ) 7.6 Hz); 1.82-1.30 (m, 23H); 0.90 (m, 9H). 13
C
NMR (CD2Cl2, 75 MHz) δ: 159.3, 158.9, 157,4, 152.3, 144.4,
140.1, 133.9, 130.3, 129.8, 129.7, 129.4, 126.4, 126.0, 125.7,
117.0, 116.9, 114.2, 114.1, 114.0, 113.0, 103.6, 68.7, 62.8, 35.5,

Synthesis of Second-Order Nonlinear Optical Chromophores
J . Org. Chem., Vol. 64, No. 12, 1999 4297
34.0, 32.9, 31.9, 31.7, 31.2, 29.5, 29.2, 23.1, 22.9, 22.8, 14.2,
14.1. HRMS: calcd for C48H56N4O2S 752.4124, found 752.4118.
Anal. Calcd for C48H56N4O2S: C, 76.56; H, 7.50; N, 7.44. Found
C, 76.48; H, 7.50; N, 7.41.
Characterizing data for trans-34 follow. Mp: 104-105 °C.
1H NMR (CD2Cl2, 300 MHz) δ: 7.81 (s, 1H); 7.47 (d, 1H, J )
16.1 Hz); 7.32 (d, 1H, J ) 9.0 Hz); 7.20 (d, 1H, J ) 16.1 Hz);
7.12 (d, 4H, J ) 8.3 Hz); 7.05 (m, 5H); 6.48 (m, 2H); 3.82 (t,
2H, J ) 6.0 Hz); 3.62 (q, 2H, J ) 5.6 Hz); 2.71 (t, 2H, J ) 7.6
Hz); 2.59 (t, 4H, J ) 7.6 Hz); 1.82-1.26 (m, 23H); 0.90 (m,
9H). 13C NMR (CD2Cl2, 75 MHz) δ: 158.7, 158.1, 156.2, 151.3,
147.7, 144.8, 139.5, 131.1, 129.7, 128.8, 128.4, 127.8, 126.0,
118.0, 117.7, 116.0, 115.0, 113.6, 104.6, 72.2, 68.7, 62.8, 35.4,
34.1, 32.9, 32.0, 31.6, 29.5, 29.4, 29.3, 23.1, 23.0, 22.8, 14.2,
14.1. HRMS: calcd for C47H57N3O2S 727.4172, found 727.4180.
Anal. Calcd for C47H57N3O2S: C, 77.54; H, 7.89; N, 5.77.
Found: C, 77.54; H, 7.88; N, 5.79.
Gen er a l P r oced u r e for th e Syn th esis of 30 or 33 fr om
23 or 25. To a solution of the styryl thiophene 23 or 25 at
-78 °C in THF was added n-butyllithium (1.2 equiv). The
resultant mixture was stirred at -78 °C for 45 min, and then
DMF (2 equiv) was added to the reaction. The reaction mixture
was stirred at -78 °C for 1 h and at room temperature for 3
h. Following workup and purification by column chromatog-
raphy, the product 29 or TBS-protected 33 was obtained as a
mixture of cis and trans isomers. These products were carried
over to the next step without further characterization.
The product from the above reaction was subjected to
deprotection using acetic acid using the procedure adapted in
the synthesis of the chromophores 26-28.
Syn th esis of th e Ch r om op h or e 32 by Kn oeven a gel
Rea ction . To a mixture of 3-phenylisoxazolone (1.47 g, 9.20
mmol), 30 (4.05 g, 6.13 mmol), and 4 Å molecular sieves in
ethanol (120 mL) was added few drops of piperidine (cat.). The
resultant mixture was stirred at reflux overnight. The solution
was concentrated and purified by flash column chromatogra-
phy to afford 3.00 g (61%) of 32 as a purple solid. Mp: 118-
The trans isomers of 30 and 33 were isolated by column
chromatography and characterized. Characterizing data for
1
trans-30 follow. H NMR (CD2Cl2, 300 MHz) δ: 9.95 (s, 1H);
1
7.35 (d, 2H, J ) 8.7 Hz); 7.15-6.94 (m, 13H); 3.67-3.58 (m,
6H); 2.92-2.81 (m, 4H); 2.58 (t, 2H, J ) 7.7 Hz); 2.06 (bs, 1H);
1.78 (m, 2H); 1.69-1.54 (m, 4H); 1.41-1.22 (m, 8H); 0.96-
0.86 (m, 6H). 13C NMR (CD2Cl2, 75 MHz) δ: 181.7, 154.3,
152.1, 149.2, 145.9, 145.1, 139.2, 135.6, 134.9, 132.8, 130.2,
129.7, 129.2, 128.8, 128.2, 125.7, 125.4, 122.0, 118.8, 72.3, 70.3,
62.0, 36.0, 35.4, 34.1, 32.7, 32.0, 31.7, 29.4, 28.8, 23.0, 22.8,
14.2, 14.1. HRMS: calcd for C40H49NO3S 623.3433, found
623.3461.
121 °C. H NMR (CD2Cl2, 300 MHz) δ: 7.81 (s, 1H); 7.59 (bd,
4H); 7.38 (d, 2H, J ) 8.6 Hz); 7.30 (d, 1H, J ) 16.0 Hz); 7.17-
7.02 (m, 11H); 6.95 (d, 2H, J ) 8.6 Hz); 3.68 (m, 6H); 2.85 (t,
2H, J ) 6.8 Hz); 2.65 (t, 2H, J ) 7.5 Hz); 2.59 (t, 2H, J ) 7.5
Hz); 2.05 (t, 1H, J ) 5.5 Hz); 1.78 (m, 2H); 1.63-1.53 (m, 4H);
1.42-1.24 (m, 8H); 0.94 (t, 3H, J ) 7.3 Hz); 0.86 (t, 3H, J )
6.8 Hz). 13C NMR (CD2Cl2, 75 MHz) δ: 170.2, 164.4, 159.7,
157.6, 149.9, 145.8, 145.1, 139.6, 138.1, 135.5, 135.1, 131.1,
130.5, 130.3, 129.9, 129.6, 129.1, 129.0, 128.7, 128.6, 126.0,
125.8, 121.6, 118.6, 109.5, 72.3, 70.2, 62.0, 36.2, 35.5, 34.1, 32.9,
32.0, 31.9, 30.0, 29.5, 23.0, 22.9, 14.2, 14.1. Overlap of one
aromatic 13C signal is assumed. HRMS: calcd for C49H54N2O4S
767.3883, found 767.3881. Anal. Calcd for C49H54N2O4S: C,
76.73; H, 7.10; N, 3.65. Found: C, 76.48; H, 7.15; N, 3.59.
1
Characterizing data for trans-33 follow. H NMR (CD2Cl2,
300 MHz) δ: 9.93 (s, 1H); 7.40 (d, 1H, J ) 16.2 Hz); 7.32 (d,
1H, J ) 8.7 Hz); 7.12 (m, 5H); 7.02 (d, 4H, J ) 8.2 Hz); 6.91
(s, 1H); 6.50 (bm, 2H); 3.82 (t, 2H, J ) 6.3 Hz); 3.63 (q, 2H, J
) 5.6 Hz); 2.89 (t, 2H, J ) 7.6 Hz); 2.58 (t, 4H, J ) 7.6 Hz);
1.81-1.23 (m, 23H); 0.91 (m, 9H). 13C NMR (CD2Cl2, 75 MHz)
δ: 181.6, 158.2, 154.5, 153.5, 150.5, 145.1, 139.1, 135.1, 129.7,
128.6, 128.4, 128.2, 125.7, 118.9, 118.4, 114.2, 105.6, 68.8, 62.9,
35.4, 34.1, 33.0, 32.0, 31.8, 29.4, 28.8, 23.0, 22.9, 22.8, 14.3,
14.2. Overlap of one aliphatic 13C signal is assumed. HRMS:
calcd for C44H57NO3S 679.4059, found 679.4058.
Ack n ow led gm en t. Support from the US Air Force
Office of Scientific Research (AFOSR grants AFS5X
F496209610387 and AFS 5 F496209610295) and US
Office of Naval Research (ONR grant N00014-95-1-
1319) are acknowledged. The research described in this
paper was performed in part by the J et Propulsion
Laboratory, (J PL) California Institute of Technology, as
part of its Center for Space Microelectronics Technology
and was supported by the Ballistic Missile Defense
Initiative Organization, Innovative Science and Tech-
nology Office, and AFOSR through an agreement with
the National Aeronautics and Space Administration
(NASA). Support from Lockheed-Martin Corp. and
Lightwave Microsystems is also acknowledged. J .M.
thanks the Summer Undergraduate Research Fellow-
ship Program at Caltech for support. We thank Galina
Levina for helpful discussions and technical assistance.
We are also thankful to the reviewers for helpful
comments.
Gen er a l P r oced u r e for th e Kn oeven a gel Rea ction
w ith Ma lon on itr ile To Syn th esize 31 a n d 34. To a solution
of the aldehyde 30 or 33 in methylene chloride were added
malononitrile (5 equiv), triethylamine (cat.), and 4 Å molecular
sieves. The resultant solution was stirred at ambient temper-
ature for 5 h. Following workup with water and methylene
chloride, the crude reaction mixture was purified by flash
column chromatography to afford 31 or 34. The major trans
isomer was isolated in pure form by column chromatography
and characterized.
1
Characterizing data for trans-31 follow. Mp: 77-79 °C. H
NMR (CD2Cl2, 300 MHz) δ: 7.83 (s, 1H); 7.35 (d, 2H, J ) 8.7
Hz); 7.23-7.01 (m, 11H); 6.93 (d, 2H, J ) 8.7 Hz); 3.67 (m,
6H); 2.84 (t, 2H, J ) 6.8 Hz); 2.70 (t, 2H, J ) 6.9 Hz); 2.58 (t,
2H, J ) 7.9 Hz); 2.06 (t, 1H, J ) 5.5 Hz); 1.79 (m, 2H); 1.61
(m, 4H); 1.41-1.28 (m, 8H); 0.90 (m, 6H). 13C NMR (CD2Cl2,
75 MHz) δ: 157.8, 154.5, 149.8, 147.7, 145.5, 144.8, 139.5,
135.3, 135.1, 130.2, 129.8, 128.7, 128.6, 128.3, 125.9, 125.7,
121.3, 117.7, 115.8, 114.7, 73.2, 72.2, 70.1, 61.8, 36.0, 35.4, 34.0,
32.7, 31.9, 31.5, 29.5, 29.4, 22.9, 22.8, 14.2, 14.1. Overlap of
one aromatic 13C signal is assumed. HRMS: calcd for
Su p p or t in g In for m a t ion Ava ila b le: 1H and 13C NMR
spectra of new compounds 3-6, unprotected alcohol 10, 10-
12, unprotected alcohol 13, 13-17, 21, 22, deprotected 22,
TBS-protected 26, 26, TBS-protected 27, TBS-protected 28, 30,
and 33. This material is available free of charge via the
Internet at http://pubs.acs.org.
C
C
43H49N3O2S: 671.3546. Found: 671.3560. Anal. Calcd for
43H49N3O2S: C, 76.86; H, 7.35; N, 6.25. Found: C, 76.60; H,
7.38; N, 6.51.
J O981707V