Synthesis and Conversions of Substituted o-[(Trimethylsilyl)methyl]benzyl p-Tolyl Sulfones to o-Quinodimethanes and Products Thereof

Article abstract of DOI:10.1021/jo970592c

Use of o-[(trimethylsilyl)methyl]benzyl p-tolyl sulfone (3) for synthesis and cycloaddition of substituted o-quinodimethanes has been investigated. Sulfone 3 is prepared from 2-methylbenzyl alcohol (4) by reactions with n-BuLi and chlorotrimethylsilane to form o-[(trimethylsilyl)methyl]-benzyl alcohol (7) which phosphorus tribromide converts to o-[(trimethylsilyl)methyl]benzyl bromide (8). Displacement of 8 with sodium p-toluenesulfinate yields 3. Sulfone 3 is alkylated at its α-sulfonyl position upon deprotonation with n-BuLi followed by methyl iodide, ethyl, butyl, allyl, and benzyl bromides, and 5-bromo-1-pentene, respectively. Acylations occur using acid chlorides. Dialkylation occurs upon further reaction with n-BuLi and an alkyl halide. 1,4-Eliminations of α,α-dialkyl sulfones 11 with tetrabutylammonium fluoride (TBAF) give α,α-dialkyl-o-quinodimethanes (29); 3 is therefore a synthon for the o-quinodimethane-α,α-dianion (34). o-Quinodimethanes 29 undergo (1) cycloaddition with acrylonitrile, acrylate esters, and alkyl fumarates to yield 1,1-disubstituted-tetrahydronaphthalenes (30) and (2) 1,5-sigmatropic rear-rangements of hydrogen to give styrenes (32). The stereochemistries of the various cycloadditions reveal significant mechanism information.

Full text of DOI:10.1021/jo970592c

2072
J . Org. Chem. 1998, 63, 2072-2085
Articles
Syn th esis a n d Con ver sion s of Su bstitu ted
o-[(Tr im eth ylsilyl)m eth yl]ben zyl p-Tolyl Su lfon es to
o-Qu in od im eth a n es a n d P r od u cts Th er eof
Brian D. Lenihan and Harold Shechter*
Department of Chemistry, The Ohio State University, Columbus, Ohio 43210
Received April 1, 1997 (Revised Manuscript Received October 14, 1997)
Use of o-[(trimethylsilyl)methyl]benzyl p-tolyl sulfone (3) for synthesis and cycloaddition of
substituted o-quinodimethanes has been investigated. Sulfone 3 is prepared from 2-methylbenzyl
alcohol (4) by reactions with n-BuLi and chlorotrimethylsilane to form o-[(trimethylsilyl)methyl]-
benzyl alcohol (7) which phosphorus tribromide converts to o-[(trimethylsilyl)methyl]benzyl bromide
(8). Displacement of 8 with sodium p-toluenesulfinate yields 3. Sulfone 3 is alkylated at its
R-sulfonyl position upon deprotonation with n-BuLi followed by methyl iodide, ethyl, butyl, allyl,
and benzyl bromides, and 5-bromo-1-pentene, respectively. Acylations occur using acid chlorides.
Dialkylation occurs upon further reaction with n-BuLi and an alkyl halide. 1,4-Eliminations of
R,R-dialkyl sulfones 11 with tetrabutylammonium fluoride (TBAF) give R,R-dialkyl-o-quin-
odimethanes (29); 3 is therefore a synthon for the o-quinodimethane-R,R-dianion (34). o-
Quinodimethanes 29 undergo (1) cycloaddition with acrylonitrile, acrylate esters, and alkyl
fumarates to yield 1,1-disubstituted-tetrahydronaphthalenes (30) and (2) 1,5-sigmatropic rear-
rangements of hydrogen to give styrenes (32). The stereochemistries of the various cycloadditions
reveal significant mechanism information.
In tr od u ction
methylsilyl)ethane and related derivatives yield their
corresponding olefins efficiently4 and (2) the fluoride
eliminative methodology is excellent for preparing 1,3-
dienes from varied 1-(benzenesulfonyl)-4-(trimethylsilyl)-
2-butenes.5
Synthesis and the chemistry of o-quinodimethanes (1)
and benzocyclobutenes (2) are subjects of considerable
interest.1 Important to the inception of this research is
that 1,4-elimination of [o-((trimethylsilyl)methyl)benzyl]-
trimethylammonium halides by fluoride ion is a versatile
method for generating substituted o-quinodimethanes
which cycloadd with dienophiles to form substituted
tetrahydronaphthalenes.2 Preparation and utilization of
trimethyl[o-[p-tolylsulfonyl)methyl]benzyl]silane (3) for
generating and determining the detailed chemistry of 1
are now reported.3 The present study has its specific
origins in that (1) fluoride-induced (trimethylsilyl)ben-
zenesulfonyl eliminations of 1-(benzenesulfonyl)-2-(tri-
Resu lts a n d Discu ssion
P r ep a r a tion of 3. Silyl sulfone 3 is now readily
prepared in multigram quantities from 2-methylbenzyl
alcohol (4) as shown in Scheme 1. Conditions which
maximize the yield (71%) of o-[(trimethylsilyl)methyl]-
benzyl alcohol (7) involve (1) reaction of 4 with n-BuLi
(2.1 equiv) in diethyl ether at 30-35 °C followed by
chlorotrimethylsilane (2.0 equiv) at -78 °C6,7 and (2)
(1) For reviews of o-quinodimethanes, benzocyclobutenes, and re-
lated chemistry with important references therein, see: (a) Klundt, I.
L. Chem. Rev. 1970, 70, 471. (b) Oppolzer, W. Synthesis 1978, 793. (c)
Thummel, R. P. Acc. Chem. Res. 1980, 1370. (d) Funk, R. L.; Vollhardt,
K. P. C. Chem. Soc. Rev. 1980, 9, 41. (e) Magnus, P.; Gallagher, T.;
Brown, P.; Pappalardo, P.; Acc. Chem. Res. 1984, 17, 35. (f) Charlton,
J . L.; Alauddin, M. M. Tetrahedron 1987, 43, 2873. (g) Pindur, U.;
Erfanian-Abdoust, H. Chem. Rev. 1989, 89, 1681. (h) Martin, N.;
Seoane, C.; Hanack, M. Org. Prep. Proc. Intl. 1991, 23, 237. (i)
Oppolzer, W. Compr. Org. Synth. 1991, 5, 388. (j) Rigby, J . H. Compr.
Org. Synth. 1991, 5, 622, 638. (k) Chou, T. Rev. Heteroatom. Chem.,
Vol. 8; Shigeru, O., Ed.; MYU K.K.: Tokyo, J apan, 1993. (l) Footnote
2 and references therein.
(2) (a) Ito, Y. Current Trends in Organic Synthesis; Pergamon
Press: New York, 1983; p 169. (b) Ito, Y.; Nakatsuka, M.; Saegusa, T.
J . Am. Chem. Soc. 1980, 102, 863. (c) Ito, Y.; Nakatsuka, M.; Saegusa,
T. J . Am. Chem. Soc. 1981, 103, 476. (d) Ito, Y.; Nakatsuka, M.;
Saegusa, T. J . Am. Chem. Soc. 1982, 104, 7609. (e) Ito, Y.; Amino, Y.;
Nakatsuka, M.; Saegusa, T. J . Am. Chem. Soc. 1983, 105, 1586. (f)
Trahanovsky, W. S.; Macias, J . R. J . Am. Chem. Soc. 1986, 108, 6820.
(3) The present results have been communicated in part by Lenihan,
B. D.; Shechter, H. Tetrahedron Lett. 1994, 35, 7505.
(4) (a) Kocienski, P. J . Tetrahedron Lett. 1979, 2649. (b) Kocienski,
P. J . J . Org. Chem. 1980, 45, 2037. (c) Paquette, L. A.; Williams, R. V.
Tetrahedron Lett. 1981, 22, 4643. (d) Hsiao, C.-N. Ph.D. Dissertation,
The Ohio State University, 1982. (e) McCullough, K. J . Tetrahedron
Lett. 1982, 23, 2223. (f) Kocienski, P. Phosphorus Sulfur 1985, 24, 97.
(g) Eisch, J . J .; Behrooz, M.; Dua, S. K. J . Organomet. Chem. 1985,
285, 121. (h) Williams, R. V.; Sung, C. A. J . Chem. Soc., Chem.
Commun. 1987, 590. (i) Hsiao, C.-N.; Shechter, H. J . Org. Chem. 1988,
53, 2688.
(5) (a) Hsiao, C.-N.; Shechter, H. Tetrahedron Lett. 1984, 25, 1219.
(b) Pegram, J . J .; Anderson, C. B. Tetrahedron Lett. 1988, 29, 6719.
(c) Meagher, T. P. Ph.D. Dissertation, The Ohio State University, 1988.
(d) Yet, L. M.S. Thesis, The Ohio State University, 1990.
S0022-3263(97)00592-6 CCC: $15.00 © 1998 American Chemical Society
Published on Web 03/17/1998

Synthesis of Quinodimethanes
Sch em e 1
J . Org. Chem., Vol. 63, No. 7, 1998 2073
Ta ble 2. Dia lk yla tion s of Lith io Su lfon e 9 to 11 w ith
P r im a r y a n d Secon d a r y Ha lid es (eq 2)
sulfone product
R
R′
yield, %
11a
11b
11c
11d
11e
11f
11g
11h
11i
methyl
ethyl
ethyl
1-propyl
butyl
allyl
allyl
4-pentenyl
2-propyl
methyl
ethyl
methyl
methyl
methyl
allyl
methyl
methyl
methyl
78
57
60
63
70
75
82
77
72
Ta ble 1. Mon oa lk yla tion s of Lith io Su lfon e 9 to 10a -d
w ith P r im a r y a n d Secon d a r y Ha lid es (eq 1)
Ta ble 3. Rea ction s of Su lfon es 10a -d w ith TBAF a n d
P r oton a tion To Give Su lfon es 27a -d
halide
sulfones 10a -d
yield, %
methyl iodide
allyl bromide
benzyl bromide
2-bromopropane
cyclohexyl bromide
10a
10b
10c
10d
10e
77
81
69
66
0
sulfones 10a -d
sulfones 27a -d
yield, %
10a ; R ) methyl
10b; R ) allyl
10c; R ) benzyl
10d ; R ) 2-propyl
27a
27b
27c
27d
67
62
70
69
hydrolysis of 6 with 10% H2SO4. Bromide 8 is obtained
(95%) from 7 and phosphorus tribromide in diethyl ether
at 25 °C. Displacement of 8 by sodium p-toluenesulfinate
in poly(ethylene glycol) (PEG, av MW 400) at 60-80 °C
then gives 3.8
Alk yla tion s a n d Acyla tion s of Su lfon es 3 a n d 10.
Sulfone 3 in THF is monoalkylated R to its sulfone group
to give 10a -c in 69-81% yields by adding n-BuLi (1.05
equiv) in THF followed by a primary, allyl, or benzyl
halide (eq 1, Table 1). A typical alkylation involves
generation of lithio derivative 9 at -78 °C, warming to
20-25 °C, cooling to -78 °C, addition of a halide, and
then warming to ∼25 °C. The reactions are followed by
the fading of the yellow color of 9, TLC, and NMR
analyses of the products. In 10a -d the R-sulfonyl
hydrogens (δ 4-5) integrate to one proton.
n-BuLi and ethyl bromide, but the synthesis requires
HMPA and a third addition of n-BuLi and ethyl bromide.
R-2-Propyl sulfone 10d is alkylated by n-BuLi and methyl
iodide in the presence of HMPA to give 11i (72%).
Evidence for dialkylations of 3 to 11a -i include accept-
able elemental analyses and the absence of 1H NMR for
R-sulfonyl protons in the products.9 Most disubstituted
sulfones (11a -i) do not give mass spectral molecular ions;
a principal ion detected is the parent minus p-toluene-
sulfinate.
R,R-Dilithio derivatives such as dilithiomethyl phenyl
sulfone (12)10 and 1-(1,1-dilithio-2-trimethylsilyl)ethyl
phenyl sulfone (13)4g are known. Reactions of n-BuLi and
3 have been investigated in efforts to prepare R,R-dilithio
sulfone 14. Addition of n-BuLi (2 equiv) in hexane to 3
at -78 °C followed by warming to 20-25 °C and then
adding methyl iodide at -78 °C gives R,R-dimethyl
sulfone 11a (9%) and R,o-dimethyl sulfone 15 (57%), the
product resulting from dimethylation of R,o-dilithio sul-
fone 16. Generation of R,o-dilithiated phenyl sulfones
has been previously reported11 even though their R,R-
dilithio isomers are more stable. Dimetalation of alkyl
phenyl sulfones by n-BuLi at -78 °C occurs in general
at the R,o-positions.11 Upon warming the R,o-derivatives
to room temperature, transmetalation occurs to form the
R,R-dilithio derivatives.11 It is not yet clear whether 11a
is formed by successive methylations of 14 or/and R-meth-
ylation of 16, proton transfer, and then methylation of
17.
Alkylations of 3 with secondary halides are less ef-
ficient because of competitive eliminations. Reaction of
9 with 2-bromopropane yields 10d along with propene
and 3. Conversion of 3 to 10d is accomplished effectively
(66%), however, by successive additions of n-BuLi and
2-bromopropane in the presence of HMPA at 0 °C. 1H
NMR evidence for 10d is the doublet for its R-sulfonyl
proton. When cycloalkylation of 9 with cyclohexyl bro-
mide is attempted, elimination to cyclohexene occurs and
3 is regenerated.
Dialkylations of 3 in one pot with primary halides are
effected via successive additions of n-BuLi and a halide
(eq 2, Table 2). Alkylations in which the second alkyl
group is methyl give the best yields. Diethyl sulfone 11b
is produced (57%) by dialkylation of sulfone 3 with
Alkylation of R,R-dimethyl sulfone 11a with n-BuLi
and methyl iodide was attempted because of the possibil-
(6) Deprotonation of 2-methylbenzyl alcohol with n-BuLi in diethyl
ether to 5 is complete in 24 h at room temperature and in 4 h under
reflux. Braun, M.; Ringer, E. Tetrahedron Lett. 1983, 24, 1233.
(7) Silane 7 is obtained in 79% yield using 3 equiv of n-BuLi (Dai-
Ho, G.; Mariano, P. S. J . Org. Chem. 1988, 53, 5113) and in 87% yield
using 5 equiv of n-BuLi and TMEDA (Lan, A. J . Y.; Heuckeroth, R.
O.; Mariano, P. S. J . Am. Chem. Soc. 1987, 109, 2738).
(9) The NMR of some of the protons and carbons of sulfone 11i are
not defined at 303 K because restricted rotation causes signal broaden-
ing. At 350 K in C6D6, the signals become discrete because molecular
rotation is increased.
(10) Eisch, J . J .; Dua, S. K.; Behrooz, M. J . Org. Chem. 1985, 50,
3674.
(11) (a) Gais, H.-J .; Vollhardt, J . Tetrahedron Lett. 1988, 29, 1529.
(b) Vollhardt, J .; Gais, H.-J .; Lukas, K. L. Angew. Chem., Int. Ed. Engl.
1985, 24, 610.
(8) Poly(ethylene glycol) is a useful solvent for preparing sulfones.
Sukata, K. Bull. Chem. Soc. J pn. 1984, 57, 613.

2074 J . Org. Chem., Vol. 63, No. 7, 1998
Lenihan and Shechter
added slowly to an R-monoalkyl sulfone and a dienophile
in acetonitrile. Each drop of TBAF produces a yellow
color which fades after ∼5 s. The mixture is then diluted
with an inert solvent, worked up, and chromatographed
on silica gel.
ity of methylation R to its silyl group via 18 to form 19.
Reaction gives however trimethyl[o-[1-methyl-1-(2,4-xy-
lylsulfonyl)ethyl]benzyl]silane (20, 68%) and thus meta-
lation of 11a occurs ortho to its sulfone group. The
abilities of phenyl sulfones to undergo ortho-metalation
continue to be impressive.12
The study shows that 10a -d , silanes containing
hydrogen R to their sulfone groups, do not undergo 1,4-
eliminations by TBAF. Only products resulting from loss
of trimethylsilyl and from retention of p-tolylsulfonyl
groups (27a -d , eq 4) are obtained. Reactions involving
sulfones 10a -d with TBAF along with the yields of
27a -d are listed in Table 3. The results indicate
formation of benzyl anions 25a -d upon removal of the
trimethylsilyl group, transfer of acidic hydrogen R to the
sulfone group, and protonation of 26a -d to 27a -d on
workup. Products 27a -d are assigned from their el-
1
emental analyses and their H NMR spectra.
R-Metallo derivatives of 3 and 10 undergo other
transformations. Thus, treatment of 3 with n-BuLi and
then reactions with benzoyl chloride and with trimethyl-
acetyl chloride in THF yield R-acyl sulfones 21a (70%)
and 21b (69%). Similarly, R-benzoyl-R-methyl sulfone
21c (72%) is obtained from 10a and n-BuLi in THF and
then benzoyl chloride. R-Acyl-R-sulfonyl derivative 21a ,
an acid readily neutralized by sodium hydroxide (1.0
equiv), undergoes o-benzoylation (84%) upon addition of
sodium hydroxide and benzoyl chloride to give 22. That
22 is a sulfonyl enol benzoate is revealed by its 13C NMR
for 24 carbon atoms, its downfield 13C absorption at δ
164 for ester carbonyl carbons, and its strong IR absorp-
tion at 1746 cm-1 for ester carbonyls. The stereochem-
istry of 22, E or Z, is not yet assignable.
The behaviors of disubstituted sulfones 11 with fluo-
ride ion were then studied. Such sulfones have no
R-sulfonyl hydrogen and undergo 1,4-eliminations to form
o-quinodimethanes 29 which are trappable by dienophiles
to give tetrahydronaphthalenes 30 (eq 5; 30-60%).
Sigmatropic 1,5-shifts of hydrogen in 31 (29 which have
(Z)-allylic hydrogen, eq 6) yield styrene derivatives (32)
in competing processes. Sulfones 33 are also obtained
by desilylation of 11 and then protonation of 28 (eq 7).
The results obtained with 11 resulting in 29 reveal that
3 is a synthon for the o-quinodimethane-R,R-dianion (34)
and are discussed specifically as follows.
R,R-Dimethyl sulfone 11a in acetonitrile reacts with
TBAF (2 equiv) in the presence of acrylonitrile (40 equiv)
at 20-25 °C to give R,R-dimethyl-o-quinodimethane (29a ,
R and R′ ) Me; eq 5, Table 4). o-Quinodimethane 29a
then undergoes (1) directed 1,4-cycloaddition of acryloni-
trile yielding 2-cyano-1,1-dimethyltetrahydronaphthalene
Beh a vior s of Tr im eth ylsilyl Su lfon es 10 a n d 11
w ith F lu or id e Rea gen ts. Fluoride-induced elimina-
tions of R-monoalkyl sulfones 10a -d were investigated
in efforts to generate and capture R-monoalkyl-o-quin-
odimethanes 23 as 1,4-cycloadducts 24 (eq 3). In a
typical experiment, TBAF (2 equiv) in acetonitrile is
(12) (a) Iwao, M.; Iihama, T.; Mahalanabis, K. K.; Perrier, H.;
Snieckus, V. J . Org. Chem. 1989, 54, 24. (b) Lamothe, M.; Anderson,
M. B.; Fuchs, P. L. Synth. Commun. 1991, 21, 1675.

Synthesis of Quinodimethanes
J . Org. Chem., Vol. 63, No. 7, 1998 2075
Et) and the 4,4-dimethyltetralin-2-carboxylate (40a , R′
) Me; 40b, R′ ) Et) esters in 3:1 ratios and 40% and
47% yields along with styrene 36 and sulfone 33a .
o-Quinodimethane 29a therefore is not captured as
efficiently or as regiospecifically by acrylates as by
acrylonitrile. Poorer regioselectivity in cycloadditions of
acrylate esters as compared to acrylonitrile has been
reported previously.13 The directions of addition of 29a
to the electronegatively substituted conjugated olefins are
interpretable on the basis of favored transition states
having diradical or dipolar character such as 41 and 42.
Further, the poorer regioselectivities with the acrylates
leading to significant amounts of 40a (R′ ) Me) and 40b
(R′ ) Et) are explained by steric interactions between
the methyl groups in 29a and the carboalkoxy groups in
the dienophiles that cause retardation in cycloaddition
to yield 39a (R′ ) Me) and 39b (R′ ) Et).
Cycloadducts (43a and 43b) of 29a with dimethyl and
diethyl fumarates (Table 4) are obtained in 57% and 58%
1
yields, respectively. The H NMR spectrum of tetrahy-
dronaphthyl dicarboxylate 43a shows a doublet at δ 2.93
with a coupling constant of 11.5 Hz for its Ha proton (44,
45). The large coupling constant suggests that the
carbomethoxy groups are trans. NOE study of 44 and
45 involving irradiation of the methyl group at δ 1.53
results in 13% enhancement of the doublet at ∼δ 2.93
and 15% for the aromatic proton doublet at δ 7.35.
Enlargement of the doublet at δ 2.9 upon irradiation at
δ 1.53 indicates that the doublet arises from proton Ha
and that the methyl which absorbs at δ 1.53 is cis to Ha.
Irradiation of the methyl group at δ 1.21 causes increases
of 13% in the multiplet at δ 3.0-3.4 and 8% in the
aromatic doublet at δ 7.35. Because irradiation at δ 1.21
causes no enhancement in the Ha region, but does enlarge
the Hb region, the methyl group which absorbs at δ 1.21
is trans to Ha. The conclusion that the methyl group
which absorbs at δ 1.21 is close to Hb provides informa-
tion regarding the conformation of 43a and evidence that
its carbomethoxy groups are trans (44 and 45). The NOE
of 43b (46 and 47) is similar to that of 43a and leads to
the conclusion that 43b has trans stereochemistry.
Cycloadducts of 29a with dimethyl and diethyl fumarates
are therefore totally trans.
(35, Table 4, 54%) and (2) sigmatropic hydrogen rear-
rangement to form styrene 36 (Table 4, 17%). Formation
of sulfone 33a (R and R′ ) Me, eq 7, Table 4, 14%) along
with polymerization of acrylonitrile and of styrene 36 are
minor processes. Production of 33 (R and R′ ) Me)
suggests that 1,4-elimination of 11a is stepwise via 28
(eq 7, R and R′ ) Me) rather than concerted.
Reactions of 29a (R and R′ ) Me) with acrylonitrile
can give two regioisomeric adducts. 1H NMR and 13C
NMR show, however, that one isomer, 35 (Table 4), is
1
greatly favored. Evidence for 35 is the H NMR doublet
of doublets at δ 2.83 for the R-cyano proton. NOE results
as summarized in 37 provide further support of the
regiochemical assignment in that irradiation at δ 1.50
gives an 8% enhancement of the doublet of doublets at δ
2.83 (Ha), a 16% increase of the aromatic doublet of
doublets at δ 7.35 (Ho), and a 6% increase of the proton
multiplet at δ 2.0-2.3 (Hb, Hc). Also, oxidation of 35 with
chromium trioxide yields a product assignable as 3-cyano-
4,4-dimethyl-1-tetralone (38).
Elimination of 11a by TBAF after admixture with
diethyl maleate was then studied. In all experiments the
product from cycloaddition of o-quinodimethane 29a (eq
5) is singularly trans-dicarboxylate 43b (Table 4). The
fact that the overall stereochemistries are identical in
the cycloaddition reactions in the experiments with 11a ,
TBAF, and either diethyl fumarate or diethyl maleate
to give 43b raise important mechanism questions as
follows.
Maleate esters are known to (1) be isomerized by
fluoride ion to fumarate esters14 and (2) undergo cycload-
ditions of conjugated dienes slower and in lower yields
than do fumarate esters.15 Reaction of 11a , TBAF, and
diethyl maleate might thus involve partial or total
isomerization of diethyl maleate to diethyl fumarate and
stepwise (with steric control) or/and concerted addition
Reactions of R,R-dimethyl sulfone 11a with TBAF-
acetonitrile were then effected in the presence of methyl
acrylate and ethyl acrylate. 1,4-Cycloadditions of 29a
with each acrylate (Table 4) give the corresponding 1,1-
dimethyltetralin-2-carboxylate (39a , R′ ) Me; 39b, R′ )

2076 J . Org. Chem., Vol. 63, No. 7, 1998
Lenihan and Shechter
Ta ble 4. P r od u cts Der ived fr om Su lfon e 11a , TBAF , a n d Dien op h iles (eqs 5-7)
particular significance is that heterogeneous reaction of
11a in acetonitrile with cesium fluoride in the presence
of diethyl maleate (2 equiv) for 3 weeks at ∼25 °C
produces trans-dicarboxylate 43b in increased (59%) yield
and diethyl maleate in increased (38%) conversion.
Although the kinetics of the above reaction systems have
not been studied in further detail, it is clear that (1) 29a
does not react concertedly with diethyl maleate16 and (2)
upon admixture of 11a , diethyl maleate, and fluoride ion
sources, isomerization of the diethyl maleate to diethyl
fumarate is extensive and then cycloaddition of 29a to
the diethyl fumarate is a major or the (near) exclusive
source of 43b.
The behaviors of R,R-diethyl sulfone 11b with TBAF-
acetonitrile in the presence of dimethyl fumarate and
diethyl fumarate were then investigated. The R,R-
diethyl-o-quinodimethane (29b, Table 5) presumably
generated undergoes 1,4-cycloadditions with the fuma-
rate esters to give trans-dicarboxylates 48a and 48b.
Competitive 1,5-hydrogen rearrangements of 29b in the
above experiments as in 50a and 50b result (Table 5) in
3-o-tolyl-2-pentenes: 49a (E) and 49b(Z). Desilylation of
11b as in eq 7 yields 33b (Table 5, R and R′ ) Et). As
expected, 29b undergoes cycloadditions less effectively
and hydrogen rearrangements more extensively than
does 29a , steric effects lead to 49a in preference to 49b,
and desilylation to its sulfone is more prevalent in 11a
than 11b.
of 29a to the diethyl fumarate to form 43b. Admixture
of 11a , TBAF, and diethyl maleate (2 equiv) in acetoni-
trile at 20-25 °C for 90 min was then found to give trans-
dicarboxylate 43b in ∼32% yield along with ∼34%
recovery of the diethyl maleate and, interestingly, ∼38%
diethyl fumarate. Cesium fluoride also causes 1,4-
elimination of 11a in acetonitrile, but the reaction is
considerably slower than that with TBAF because cesium
fluoride is much less soluble in the acetonitrile. Of
Eliminations of R-ethyl-R-methyl sulfone 11c by fluo-
ride ion were then investigated to determine the various
behaviors of R-ethyl-R-methyl-o-quinodimethanes 29c
and 29d (Table 5). Reactions of 11c with TBAF in
acetonitrile at 20-25 °C yield styrene derivatives (eq 6)
(13) Ito, Y.; Nakatsuda, M.; Saegusa, T. J . Am. Chem. Soc. 1982,
104, 7609.
(14) Ito, Y.; Nakajo, E.; Saegusa, T. Synth. Commun. 1986, 16, 1073.
(15) (a) Arbuzov, B. A.; Fuzhenkova, A. V.; Devyatova, G. M. J . Gen.
Chem. USSR 1971, 41, 721. (b) Blankenburg, V. B.; Fiedler, H.;
Hampel, M.; Hauthal, H. G.; J ust, G.; Kahlert, K.; Korn, J .; Mu¨ller,
K.-H.; Pritzkow, W.; Reinhold: Y.; Ro¨llig, M.; Sauer, E.; Schnurpfeil,
D.; Zimmermann, G. J . Prakt. Chem. 1974, 316, 804. (c) J ung, M. E.;
McCombs, C. A. Tetrahedron Lett. 1976, 2935. (d) Inomata, K.;
Kinoshita, H.; Takemoto, H.; Murata, Y.; Kotake, H. Bull. Chem. Soc.
J pn. 1978, 51, 3341. (e) Zutterman, F.; Krief, A. J . Org. Chem. 1983,
48, 1135. (f) Charlton, J . L.; Alauddin, M. M.; Penner, G. H. Can. J .
Chem. 1986, 64, 793. (g) Meier, H.; Eckes, H.-L.; Niedermann, H.-P.;
Kolshorn, H. Angew. Chem., Int. Ed. Engl. 1987, 26, 1046. (h) Noguchi,
M.; Kiriki, Y.; Ushijima, T.; Kajigaeshi, S. Bull. Chem. Soc. J pn. 1990,
63, 2938. The lower reactivity of dimethyl maleate is explained by steric
effects between the dienophile substituents and the diene. The transi-
tion states become more crowded when the carboalkoxy groups are
cis. (i) Miki, T.; Matsuo, T. Chem. Pharm. Bull. 1971, 19, 858 and
references therein.
(16) (a) Reaction of dimethyl maleate with R,R′-dimethyl-o-quin-
odimethane generated by fluoride-induced elimination yields cis-2,3-
dicarbomethoxy-1,4-dimethyl-1,2,3,4-tetrahydronaphthalene. The prod-
uct is formed because the o-quinodimethane cannot undergo 1,5-
sigmatropic rearrangement. Cycloaddition of dimethyl maleate to yield
the cis adduct also occurs with the unsubstituted o-quinodimethane,
which cannot undergo 1,5-sigmatropic rearrangement. Ito, Y.; Nakat-
suda, M.; Saegusa, T. J . Am. Chem. Soc. 1982, 104, 7609. (b)
Cycloadditions of o-quinonemethide N-alkylimines with fumarate
esters give trans-2,3-dicarboalkoxy cycloadducts in good yields, whereas
maleate esters give low yields of mixtures of cis- and trans-2,3-
dicarboalkoxy cycloadducts in which the trans adducts dominate. Ito,
Y.; Nakajo, E.; Saegusa, T. Synth. Commun. 1986, 16, 1073.

Synthesis of Quinodimethanes
J . Org. Chem., Vol. 63, No. 7, 1998 2077
Ta ble 5. P r od u cts Der ived fr om Su lfon es 11b, 11c, 11e, 11g, a n d 11i w ith TBAF in th e Absen ce a n d P r esen ce of
Dien op h iles
nonvolatile materials. o-Quinodimethane 29c is expected
to be formed more extensively than 29d because of steric
51a (45%) and 51b (3.3%) in a 93:7 ratio along with
desilylated sulfone 33b (eq 7; R ) Me, R′ ) Et) and

2078 J . Org. Chem., Vol. 63, No. 7, 1998
Lenihan and Shechter
effects in elimination of 11c by fluoride ion. Sigmatropic
isomerizations of 29c and 29d with steric control as in
52 and 53 then yield 51a in favor of 51b.
esters are not captured as efficiently or as regioselectively
by 29c and 29d as is acrylonitrile and (2) 1,5-sigmatropic
rearrangements of 29c and 29d to 51a and 51b are more
pronounced in the presence of methyl acrylate than in
acrylonitrile.
Cyanotetrahydronaphthalenes 54a [(E), 14%] and 54b
[(Z), 28%] (Table 5), the cycloadducts of 29c and 29d with
acrylonitrile, are formed in a 1:2 ratio. Styrenes 51a
(24%) and 51b (5%) along with desilylated sulfone 33c
(eq 7; R ) Me, R′ ) Et) are also produced. Diastereomers
54a and 54b were separated by gas chromatography and
their stereochemistries determined by NOE methods.
Cycloadduct 54a , which has the shorter GC retention
time, was irradiated at δ 1.45 (55) for its methyl group.
The absorption for the R-cyano proton (Ha) at δ 3.05 in
55 is enhanced 1%. Irradiation of 54b at δ 1.41 causes
a 7% increase in absorption for the R-cyano proton at δ
2.90 (56). Because of the larger enhancement in 56, its
R-cyano proton and its methyl group are cis whereas the
R-cyano proton Ha is trans to the methyl group in 55.
The regioselectivities in formation of 54a and 54b from
29c and 29d are similar to that for cycloadditions of
unsymmetrical dienes and dienophiles17 and are consis-
tent with reaction mechanisms in which 29c and 29d add
to acrylonitrile as diradical or dipolar reactants 57 and
58. Of further interest, on the basis that the principal
o-quinodimethane which reacts with acrylonitrile is 29c,
is that the transition state leading to 54b as the major
cycloadduct may be stabilized by Alder-Stein endo
interaction as in 59.
Reactions of 11c with TBAF were then effected in the
presence of dimethyl fumarate and diethyl fumarate. The
results are summarized in Table 5. Of note are (1) the
fumarates are captured by 29c and 29d to give 62a ,b
and 63a ,b in 47-51% yields, (2) the initial trans stere-
ochemistries of the carboalkoxy groups are totally re-
tained in the cycloaddition processes, and (3) styrenes
51a and 51b along with desilylated sulfone 33c (R ) Me,
R′ ) Et) are formed. The 2,3-dicarboethoxytetrahy-
dronaphthalenes 63a and 63b are obtained in a 55:45
ratio as judged by NMR and are preparatively separable
by GC. The configurations of 63a and 63b are assigned
by NOE. Irradiation of the methyl group of the cycload-
duct, 63a , with the lower retention time gives a 14%
enhancement at the multiplet corresponding to proton
Hb as in 64. Irradiation of the methyl group of the
cycloadduct, 63b, with the higher retention time results
in a 16% increase at the doublet corresponding to proton
Ha as in 65. Further, the diastereomers with their
3-carboethoxy groups cis to the ethyl groups and there-
fore more hindered have the shorter retention times.
Finally, as expected, the overall behavior of 11c and
TBAF with dimethyl fumarate is essentially identical to
that with diethyl fumarate (Table 5).
Study was then made of decompositions (Table 5) of
R-methyl-R-substituted sulfones 11e (R ) Bu, R′ ) Me),
11g (R ) Allyl, R′ ) Me), and 11i (R ) 2-Propyl, R′ )
Me) by TBAF in the presence of dimethyl fumarate (2-4
equiv). The principal purpose of these experiments was
to determine if o-quinodimethanes more hindered and
presumably less enophilic than those previously studied
are readily captured by dimethyl fumarate. Further
objectives were to assign the stereochemistries of cy-
cloadducts and search for other intramolecular reactions
of o-quinodimethanes. o-Quinodimethanes 29e and 29f,
29g and 29h , and 29i and 29j, presumed as generated
from 11e, 11g, and 11i, have thus been found to react
with dimethyl fumarate (Table 5) to yield 2,3-dicar-
bomethoxytetrahydronaphthalenes 66a and 66b, 68a and
68b , and 70a and 70b , respectively. The o-quin-
odimethanes also undergo 1,5-hydrogen rearrangements
to give their corresponding styrene derivatives (eq 6;
Table 5; 67 and 69a and 69b). Desilylations of 11e, 11g,
and 11i occur as expected (eq 7); sulfones 33 were not
characterized in detail.
Sulfone 11c in the presence of methyl acrylate is
converted by TBAF in acetonitrile (Table 5) to 2- and
3-carbomethoxytetrahydronaphthalenes 60 (30%), sty-
renes 51a (31%) and 51b (5%), and desilylated sulfone
33c (eq 7; R ) Me, R′ ) Et; 13%). Similar results are
obtained with ethyl acrylate (Table 5). Four isomeric
carbomethoxytetrahydronaphthalenes (60) are possible
from 1,4-cycloadditions of methyl acrylate to 29c and
29d . The same possibilities exist in conversions of 29c
and 29d by ethyl acrylate to 61. All attempts to separate
60 or 61 or assign their structures precisely by NMR
methods failed. It is clear however in the above elimina-
tion-cycloaddition experiments with 11c that (1) acrylate
The stereochemistries of 66a and 66b, 68a and 68b,
and 70a and 70b were established as follows. In 43a ,
43b, and 63b, the methyl groups at C-1 which are trans
to the carboalkoxy groups at C-2 show 1H NMR at δ
1.50-1.54 whereas in 43a , 43b, and 63a , the cis methyls
at C-1 absorb at δ 1.20-1.22. Cycloadducts 66b, 68b,
(17) For reviews of the mechanisms of Diels-Alder reactions, see:
(a) Sauer, J . Angew. Chem., Int. Ed. Engl. 1967, 6, 16. (b) Martin, J .
G.; Hill, R. K. Chem. Rev. 1961, 61, 537. (c) Alder, K.; Stein, G. Angew.
Chem. 1937, 50, 510. (d) Woodward, R. B.; Baer, H. J . Am. Chem. Soc.
1944, 66, 645. (e) Sauer, J .; Sustmann, R. Angew. Chem. 1980, 92,
773. (f) Van Mele, B.; Huybrechts, G. Int. J . Chem. Kinet. 1989, 21,
967.

Synthesis of Quinodimethanes
J . Org. Chem., Vol. 63, No. 7, 1998 2079
and 70a having their C-1 methyls and their C-2 car-
1
bomethoxy groups trans are assigned from their H NMR
at δ 1.50, 1.51, and 1.56, respectively. The stereochem-
istry of pure 70a upon isolation by MPLC is assigned
1
much more comprehensively from its H NMR and NOE
as now described. Cycloadduct 70a (Table 5) exhibits a
doublet of doublets for Hd with a superimposed doublet
for Ha at δ 2.8-2.9 (71). The large coupling constant of
the superimposed doublet at 12.3 Hz for Ha supports the
trans stereochemical assignments of the carbomethoxy
groups. A doublet of doublets with coupling constants
of 6.6 and 16.6 Hz for proton Hc is observed at δ 3.15-
3.30, and Hb exhibits a doublet of doublet of doublets with
coupling constants of 12.3, 11.2, and 6.6 Hz, respectively.
The stereochemical assignment of 70a is finalized from
its NOE irradiation (71) at δ 1.56 resulting in 19%
enhancement of the doublet at δ 2.90 corresponding to
Ha rather than to Hb. Of particular interest is that 70a
and 70b are produced in ∼7:1 ratio when, upon consid-
eration of conformational effects, 70b is predicted to be
less strained than 70a . An interpretation of the observed
stereochemical results is that endo transition states
involving maximum overlap for formation of 70a and 70b
come early and thus 70a is formed in preference to 70b
because the steric repulsion of the C1-carbomethoxy
group with the 2-propyl and the methyl group in 72 is
considerably less than that in 73.
functionally substituted o-quinodimethanes as prepared
from 3 is now in progress.
Exp er im en ta l Section
All melting points are uncorrected. Proton shift values are
reported in parts per million (ppm) from tetramethylsilane on
the δ scale when CDCl3 is used as the solvent with residual
CHCl3 at δ 7.26 as an internal reference. Carbon chemical
shifts are reported in ppm relative to the center line of the
CDCl3 triplet (77.0 ppm). Elemental analyses of purified
products were performed by Micro Analysis, Wilmington, DE,
or Atlantic Microlab, Norcross, GA. All reactions were con-
ducted under argon unless otherwise noted. Solvents and
reagents were dried and purified when deemed necessary.
Analytical thin-layer chromatography was performed with EM
silica gel 60 F254 plates. Column chromatography was effected
on EM 70-230 mesh silica gel 60 or Scientific Adsorbents 63-
200 mesh silica gel. The chromatography solvent is denoted
as the proportion of solvent by volume.
o-[(Tr im eth ylsilyl)m eth yl]ben zyl Alcoh ol (7). n-BuLi
(661 mL, 1719 mmol, 2.60 M in hexane) was added to
2-methylbenzyl alcohol (4, 100 g, 819 mmol) in anhydrous
diethyl ether (1500 mL) at 0 °C. The mixture was warmed to
room temperature, refluxed for 24 h, cooled to -78 °C, treated
with chlorotrimethylsilane (260 mL, 2048 mmol), and warmed
to room temperature. At -20 °C, the yellow color faded. After
2 h, 10% H2SO4 was added (dropwise initially) and the mixture
was stirred overnight. The layers were then separated, and
the aqueous phase was extracted with diethyl ether. The
combined ether extracts were washed with saturated NaCl,
dried over MgSO4, and concentrated. Distillation of the
Fluoride ion elimination of R,R-diallyl sulfone 11f
(Table 2) in acetonitrile containing dimethyl fumarate
(4 equiv) is instructive in that 4-(2-tolyl)-1,3,5-hexatrienes
76 and 77 (eq 9) are formed in 85:15 ratios in >55% yield
by 1,5-hydrogen rearrangements of R,R-diallyl-o-quin-
odimethane (74). Of note are that 74 is not trapped by
dimethyl fumarate and does not form the intramolecular
Diels-Alder cycloadduct 75 (eq 8). Further, 11h is
converted by TBAF/acetonitrile to styrene derivative 80
(eq 11, 53%). Under the designated conditions, 78 does
not form 79 (eq 10). As expected, appropriately R,R-
disubstituted-o-quinodimethanes as generated by the
present methodologies undergo (1,5)-sigmatropic shifts
of hydrogen rather than intra- or intermolecular cycload-
ditions.
The generation and chemistry of various R,R-dialkyl-
o-quinodimethanes (29) as obtained by fluoride ion
eliminations of R,R-disubstituted sulfones 11 have been
described. Determination of the chemistry of various

2080 J . Org. Chem., Vol. 63, No. 7, 1998
Lenihan and Shechter
concentrate in a Vigreaux column gave 7 (bp 94 °C, 0.95
mmHg). Fractions contaminated with unhydrolyzed material
were treated with 10% H2SO4 and diethyl ether, worked up
as before, and distilled under reduced pressure to yield pure
7 (total yield 112.6 g, 71%). The spectroscopic properties of 7
agree with that reported:7,18 MS(EI) m/e (relative intensity)
179,.09 (12), 161.08 (25), 104.06 (100), 73.05 (22).
[o-(Br om om eth yl)ben zyl]tr im eth ylsila n e (8). Phospho-
rus tribromide (20 mL, 211 mmol, 1.12 equiv) was added to 7
(109.4 g, 563 mmol) in diethyl ether (600 mL) at 0 °C. The
mixture was stirred at room temperature 2 h, cooled in ice,
and treated with water, and the layers were separated. The
aqueous layer was extracted with diethyl ether. The combined
organic extracts were washed with 1 M NaHSO3, saturated
NaHCO3, and saturated NaCl, dried over MgSO4, concen-
trated, and vacuum distilled to give 8 (137.3 g, 95%, bp 88 °C,
0.9 mmHg). Spectroscopic data for 87 agree with those re-
ported: MS(EI) m/e (relative intensity) 258.03 (3), 256.03 (3),
243.00 (11), 241.00 (10), 177.11 (57), 145.05 (18), 104.06 (100),
73.05 (70), 45.02 (22); HRMS calcd for C11H17BrSi 256.0283,
found 256.0281.
(mp 148-149.5 °C): IR (KBr) 1600, 1300, 1255, 1150, 1090,
1
850 cm-1; H NMR (CDCl3) δ -0.32 (9H, s), 1.38 (1H, d, J )
14.8 Hz), 1.66 (1H, d, J ) 14.7 Hz), 2.39 (3H, s), 3.40 (1H, dd,
J ) 10.6, 13.8 Hz), 3.80 (1H, dd, J ) 13.8, 3.8 Hz), 4.67 (1H,
dd, J ) 10.6, 3.8 Hz), 6.79 (13H, m); 13C NMR (CDCl3) δ -1.4
(q), 21.5 (q), 22.1 (t), 34.6 (t), 67.7 (d), 124.3 (d), 126.7 (d), 128.1
(d), 128.4 (d), 128.6 (s), 128.8 (d), 129.1 (d), 129.3 (d), 129.4
(d), 129.5 (d), 134.6 (s), 136.9 (s), 142.0 (s), 144.3 (s); MS(EI)
m/e (relative intensity) 267.16 (9), 229.08 (12), 73.02 (100).
Anal. Calcd for C25H30O2SSi: C, 71.04; H, 7.15. Found: C,
71.00; H, 7.29.
Tr im et h yl[o-[2-m et h yl-1-(p -t olylsu lfon yl)p r op yl]b en -
zyl]sila n e (10d ). To 3 (5.00 g, 15.0 mmol) in THF (100 mL)
at -78 °C was added n-BuLi (6.5 mL, 15.0 mmol, 1 equiv, 2.30
M in hexane). After being warmed to room temperature, the
solution was cooled to 0 °C and treated with HMPA (7.8 mL,
45 mmol, 3 equiv) and 2-bromopropane (1.42 mL, 15.0 mmol,
1 equiv). The mixture was maintained at 0 °C for 2.5 h and
cooled to -78 °C, and then n-BuLi (1.30 mL, 3.0 mmol, 0.20
equiv, 2.30 M in hexane) was added. The mixture was warmed
to 0 °C and treated with 2-bromopropane (0.35 mL, 3.75 mmol,
0.25 equiv). After 2.5 h at 0 °C, the mixture was reacted
further with n-butyllithium (0.33 mL, 0.76 mmol, 0.05 equiv)
followed by 2-bromopropane (0.07 mL, 0.76 mmol, 0.05 equiv).
After 1.75 h at 0 °C, when TLC showed that almost all of the
3 had reacted, water and diethyl ether were added. The
organic layer was worked up as for 10a and concentrated to a
solid (5.54 g) which was recrystallized from methanol to give
10d (3.41 g, mp 74-78 °C, a white solid): IR (KBr) 1596, 1284,
1249, 1144, 1080, 844 cm-1; 1H NMR (CDCl3) δ -0.06 (9H, s),
0.88 (3H, d, J ) 6.8 Hz), 1.33 (1H, d, J ) 14.8 Hz), 1.45 (3H,
d, J ) 6.5 Hz), 1.77 (1H, d, J ) 14.7 Hz), 2.31 (3H, s), 2.77-
2.95 (1H, m), 4.23 (1H, d, J ) 9.3 Hz), 6.70-6.80 (1H, m),
7.00-7.13 (4H, m), 7.26-7.30 (2H, br d), 7.45-7.52 (1H, m);
13C NMR (CDCl3) δ -0.8, 21.4, 21.9, 22.4, 22.6, 29.1, 72.2,
124.4, 127.7, 128.6, 128.9, 129.2, 129.5, 130.5, 136.2, 141.0,
143.7; MS(EI) m/e (relative intensity) 219.16 (6), 73.04 (100).
Anal. Calcd for C21H30O2SSi: C, 67.33; H, 8.07. Found: C,
67.39; H, 8.10. Additional 10d was obtained by crystallization
from the mother liquor (0.33 g, total yield 3.74 g, 66%).
P r oced u r e B (Ta ble 2) for Dia lk yla t ion of 3. Tr i-
m et h yl[o-[1-m et h yl-1-(p -t olylsu lfon yl)et h yl]b en zyl]si-
la n e (11a ). n-BuLi (13.4 mL, 31.6 mmol, 2.35 M in hexane)
was added to 3 (10.00 g, 30.1 mmol) in anhydrous THF (200
mL) at -78 °C. The yellow mixture was warmed to room
temperature and cooled to -78 °C, and methyl iodide (1.97
mL, 31.6 mmol) was added. The solution was warmed to room
temperature and cooled to -78 °C, and n-BuLi (13.4 mL, 31.6
mmol, 2.35 M in hexane) was added. The mixture was
warmed to room temperature and then cooled to -78 °C.
Methyl iodide (2.06 mL, 33.1 mmol) was added, and the
mixture was warmed to room temperature. After the mixture
was diluted with diethyl ether and extracted with water, the
organic layer was washed with saturated NaCl, dried over
MgSO4, and concentrated to an oil which solidified. Recrys-
tallization from methanol yielded 11a as a white solid (8.48
g, 78%, mp 79-83 °C): IR (KBr) 1605, 1300, 1255, 1160, 1135,
Tr im eth yl[o-[(p-tolylsu lfon yl)m eth yl]ben zyl]sila n e (3).
A mixture of 8 (137.2 g, 533 mmol), sodium p-toluenesulfinate
hydrate (137 g, 600 mmol), and poly(ethylene glycol) (220 mL,
av MW 400, dried over 4 Å molecular sieves) was stirred at
80-100 °C for 5.5 h and then diluted with water. The
precipitate formed was vacuum-filtered and recrystallized from
methanol to yield 3 (136.6 g, 77%, mp 122-123 °C). A second
crop of 3 was obtained (6.16 g, 3%, mp 120-122 °C, total yield
80%). Spectral data for 3: IR (KBr) 1600, 1310, 1295, 1255,
1
1145, 1090, 860 cm-1; H NMR (CDCl3) δ -0.06 (9H, s), 1.95
(2H, s), 2.42 (3H, s), 4.30 (2H, s), 6.91-7.48 (8H, m); 13C NMR
(CDCl3) δ -1.6, 21.6, 23.5, 60.2, 124.3, 125.0, 128.6, 128.7,
129.4, 129.6, 132.1, 135.4, 140.9, 144.6; MS(EI) m/e (relative
intensity) 177.11 (22), 104.06 (100), 73.05 (54); HRMS calcd
for C18H24O2SSi 332.1266, found 332.1304. Additional crystal-
lizations from carbon tetrachloride and ligroin yielded an
analytical sample. Anal. Calcd for C18H24O2SSi: C, 65.02; H,
7.27. Found: C, 64.66; H, 7.11.
P r oced u r e A (Ta ble 1) for Mon osu bstitu tion of o-[(Tr i-
m eth ylsilyl)m eth yl]ben zyl p-Tolyl Su lfon e (3) w ith Elec-
tr op h iles. Tr im eth yl[o-[1-(p-tolylsu lfon yl)eth yl]ben zyl]-
sila n e (10a ). n-BuLi (7.5 mL, 9.5 mmol, 1.27 M in hexane)
was added to 3 (3.00 g, 9.02 mmol) in anhydrous THF (60 mL)
at -78 °C. The mixture became yellow, was warmed to room
temperature, and then cooled in dry ice-acetone, and methyl
iodide (0.59 mL, 9.47 mmol) was added. The mixture was
warmed to room temperature and diluted with water and
dichloromethane, and the layers were separated. The organic
layer was washed with saturated NaCl, dried over MgSO4, and
concentrated to an oil which solidified. The white product was
recrystallized from ligroin to yield 10a (2.41 g, 77%, mp 86-
87 °C): IR (KBr) 1600, 1310, 1300, 1255, 1155, 860, cm-1; 1H
NMR (CDCl3) δ -0.08 (9H, s), 1.64 (1H, d, J ) 14 Hz), 1.72
(3H, d, J ) 7 Hz), 1.97 (1H, d, J ) 14.3 Hz), 2.37 (3H, s), 4.47
(1H, q, J ) 7 Hz), 6.80-7.42 (8H, m); 13C NMR (CDCl3) δ -1.8,
14.5, 21.5, 23.4, 60.7, 124.3, 128.1, 128.2, 129.0, 129.2, 129.4,
130.4, 134.0, 140.4, 144.3; MS(EI) m/e (relative intensity)
191.13 (87), 73.05 (100). Anal. Calcd for C19H26O2SSi: C,
65.85; H, 7.56. Found: C, 65.62; H, 7.60.
Tr im et h yl[o-[1-(p -t olylsu lfon yl)-3-b u t en yl]b en zyl]si-
la n e (10b). Procedure A (Table 1), a white solid, yield 81%
(mp 67-69 °C): IR (KBr) 1645, 1600, 1315, 1290, 1260, 1150,
1090, 860 cm-1; 1H NMR (CDCl3) δ -0.06 (9H, s), 1.58 (1H, d,
J ) 14.6 Hz), 1.95 (1H, d, J ) 14.5 Hz), 2.39 (3H, s), 2.86 (1H,
m), 3.15 (1H, m), 4.48 (1H, dd), 4.98 (1H, br d), 5.10 (1H, br
d), 5.65 (1H, m), 6.84-7.37 (8H, m); 13C NMR (CDCl3) δ -1.1,
21.6, 23.0, 33.3, 65.5, 118.4, 124.4, 128.2, 128.7, 128.8, 129.1,
129.4, 129.6, 133.6, 134.3, 141.6, 144.4; MS(EI) m/e (relative
intensity) 217.14 (16), 73.05 (100). Anal. Calcd for C21H28O2-
SSi: C, 67.69; H, 7.57. Found: C, 67.19; H, 7.59.
1
1080, 855 cm-1; H NMR (CDCl3) δ 0.03 (9H, s), 1.89 (6H, s),
2.36 (3H, s), 2.56 (2H, s), 6.81-7.28 (8H, m); 13C (CDCl3) δ
0.5, 21.5, 26.1, 26.6, 67.7, 123.7, 128.0, 128.7, 130.1, 130.5,
131.9, 132.5, 133.6, 142.9, 144.0; MS(EI) m/e (relative inten-
sity) 205.15 (52), 73.05 (100). Anal. Calcd for C20H28O2SSi:
C, 66.62; H, 7.83. Found: C, 66.29, H, 7.72.
[o-[1-E t h y l-1-(p -t o ly ls u lfo n y l)p r o p y l]b e n z y l]t r i -
m eth ylsila n e (11b). To 3 (2.00 g, 6.01 mmol) in THF (30
mL) at -78 °C was added n-BuLi (2.3 mL, 6.3 mmol, 2.71 M
in hexane). The solution was warmed to room temperature,
cooled to -78 °C, and treated with HMPA (3.1 mL, 18 mmol)
and ethyl bromide (0.47 mL, 6.3 mmol). When TLC showed
that all starting material had reacted, the mixture was cooled
to -78 °C and n-BuLi (2.3 mL, 6.3 mmol, 2.71 M in hexane)
was added. After being warmed to room temperature, the
bright red solution was cooled to -78 °C, treated with ethyl
bromide (0.49 mL, 6.6 mmol), and warmed to room tempera-
ture. TLC showed that the alkylations were about half
Tr im e t h yl[o-[r-(p -t olylsu lfon yl)p h e n e t h yl]b e n zyl]-
sila n e (10c). Procedure A (Table 1), a white solid, yield 69%
(18) Shih, C.; Swenton, J . S. J . Org. Chem. 1982, 47, 2668.

Synthesis of Quinodimethanes
J . Org. Chem., Vol. 63, No. 7, 1998 2081
complete. The mixture was again treated with n-BuLi at -78
°C (1.1 mL, 3.0 mmol, 2.71 M in hexane) followed by ethyl
bromide at -78 °C (0.30 mL, 4.0 mmol). TLC showed that
reaction of 3 was mostly complete. The mixure was worked
up (procedure B) and concentrated. Chromatography on silica
gel using 1:19 ethyl acetate:ligroin yielded 11b as a white solid
(1.34 g, 57%, mp 70-76 °C): IR (KBr) 1597, 1300, 1244, 1143,
1078, 849 cm-1; 1H NMR (CDCl3) δ -0.05 (9H, s), 1.07 (6H, t,
J ) 7.3 Hz), 2.30-2.38 (2H, m, J ) 7.4 Hz), 2.35 (3H, s), 2.48
(2H, s), 2.61-2.75 (2H, sextet, J ∼ 7.3 Hz), 6.75-6.87 (2H,
m), 7.00-7.18 (6H, m); 13C NMR (CDCl3) δ -0.2, 9.3, 21.5, 25.2,
26.8, 75.2, 123.5, 127.6, 128.6, 130.1, 131.8, 131.9, 132.6, 133.3,
143.8, 144.0 cm-1; MS(EI) m/e (relative intensity) 233.17 (45),
73.05 (100). Recrystallization from ligroin yielded an analyti-
cal sample (mp 75-78 °C). Anal. Calcd for C22H32O2SSi: C,
67.99; H, 8.30. Found: C, 67.97; H, 8.41.
methyl iodide, and workup gave an oil which on chromatog-
raphy yielded 11h (0.478 g, 77%): IR (neat) 1641, 1597, 1298,
1
1248, 1143, 846 cm-1; H NMR (CDCl3) δ 0.04 (9H, s), 1.19-
1.38 (2H, m), 1.89 (3H, s), 1.98-2.14 (4H, m), 2.39 (3H, s), 2.50
(1H, d, J ) 14.8), 2.64-2.76 (1H, m), 4.94-5.03 (2H, m), 5.67-
5.83 (1H, m), 6.85-7.25 (8H, m); 13C NMR (CDCl3) δ -0.5,
21.5, 23.0, 23.7, 25.6, 33.8, 36.1, 71.3, 115.2, 123.7, 127.9, 128.7,
130.3, 131.1, 131.6, 131.9, 132.4, 137.7, 143.5, 144.0; MS(EI)
m/e (relative intensity) 177.11 (19), 91.05 (19), 73.05 (100).
[o-[1,2-Dim eth yl-1-(p-tolylsu lfon yl)p r op yl]ben zyl]tr i-
m eth ylsila n e (11i). To 10d (3.00 g, 8.01 mmol) in THF (60
mL) at -78 °C was added n-BuLi (3.80 mL, 8.81 mmol, 2.35
M in hexane). The red-orange mixture was warmed to room
temperature and then cooled to -78 °C, and HMPA (2.8 mL,
16 mmol) and methyl iodide (0.75 mL, 12 mmol) were added.
The mixture was worked up (procedure B) and concentrated
to an oil which crystallized from methanol to yield 11i (2.00
g, mp 79-83 °C). A second crop of 11i was obtained (0.24 g,
Tr im et h yl[o-[1-m et h yl-1-(p -t olylsu lfon yl)p r op yl]b en -
zyl]sila n e (11c). Procedure B (Table 2), alkylation of 3 using
n-BuLi and ethyl bromide followed by n-BuLi and methyl
iodide, gave 11c which crystallized from methanol as a white
solid, yield 60% (mp 70-73 °C): IR (KBr) 1600, 1305, 1290,
total yield 72%): IR (KBr) 1597, 1283, 1248, 1149, 844 cm-1
;
1H NMR (CDCl3, 303 K) δ 0.02 (9H, s), 0.73 (3H, d, J ) 6.9
Hz), 1.45 (3H, d, J ) 6.5 Hz), 1.77 (3H, s), 2.29 (3H, s), 3.47-
3.51 (1H, m), 6.85 (2H, br s), 6.94-7.09 (4H, m), 7.10-7.14
1
1250, 1150, 1080, 860 cm-1; H NMR (CDCl3) δ 0.03 (9H, s),
1
0.84 (3H, t), 1.86 (3H, s), 1.98-2.15 (2H, d and superimposed
m), 2.37 (3H, s), 2.53 (1H, d, J ) 14.8 Hz), 2.67-2.78 (1H, m),
6.85-7.30 (8H, m); 13C NMR (CDCl3) δ -0.5, 8.2, 21.5, 23.1,
25.8, 29.5, 71.7, 123.7, 127.8, 128.7, 130.3, 130.8, 131.7, 132.0,
132.5, 143.7, 144.0; MS(EI) m/e (relative intensity) 219.15 (68)
73.05 (100). Recrystallizations from ligroin yielded an analyti-
cal sample (mp 77-79 °C). Anal. Calcd for C21H30O2SSi: C,
67.33; H, 8.07. Found: C, 67.31; H, 8.23.
(2H, m); H NMR (C6D6, 350 K) δ 0.03 (9H, s), 0.63 (3H, d, J
) 6.9 Hz), 1.53 (3H, d, J ) 6.5 Hz), 1.74 (3H, s), 1.85 (3H, s),
2.48 (1H, d, J ) 14.1 Hz), 2.63 (1H, d, J ) 14.9 Hz), 3.61 (1H,
septet, J ) 6.7 Hz), 6.63 (2H, d), 6.69-6.76 (1H, m), 6.86-
6.90 (2H, m), 7.28-7.32 (3H, d and superimposed m); 13C NMR
(CDCl3) δ -0.3, 17.3, 18.8, 19.9, 21.4, 25.7, 32.5, 76.1, 124.0,
127.5, 128.4, 129.6, 130.6, 132.5, 134.6, 142.5, 143.4; 13C NMR
(C6D6, 350 K) δ -0.09 (q), 17.8 (q), 19.1 (q), 20.1 (q), 21.0 (q),
26.4 (t), 32.9 (d), 76.6 (s), 124.4 (d), 127.6 (d), 128.6 (d), 130.3
(d), 131.2 (d), 132.9 (d), 136.0 (s), 136.5 (s), 143.0 (s), 143.1 (s).
Recrystallization of 11i from ligroin gave an analytical sample,
mp 82-84 °C. Anal. Calcd for C22H32O2SSi: C, 67.99; H, 8.30.
Found: C, 68.06; H, 8.30.
Tr im eth yl[o-[1-m eth yl-1-(p-tolylsu lfon yl)pen tyl]ben zyl]-
sila n e (11e). Procedure B (Table 2), alkylation of 3 with
n-BuLi and 1-bromobutane followed by n-BuLi and methyl
iodide, gave 11c which crystallized from methanol as a white
solid, yield 70% (mp 70-76 °C): IR (neat film) 1600, 1305,
1250, 1150, 850 cm-1
;
1H NMR (CDCl3) δ 0.03 (9H, s), 0.87
Alk yla t ion of Dilit h io 3 w it h Met h yl Iod id e. Tr i-
m eth yl[o-[1-(2,4-xylylsu lfon yl)eth yl]ben zyl]sila n e (15).
n-BuLi (1.40 mL, 3.79 mmol, 2.5 equiv, 2.71 M in hexane) was
added to 3 (0.498 g, 1.50 mmol) and THF (10 mL) at -78 °C.
The dark red mixture was warmed to room temperature,
stirred for 1 h, and cooled to -78 °C, and methyl iodide was
added (0.28 mL, 4.5 mmol). The yellow solution was warmed
to room temperature, diluted with water, and extracted with
diethyl ether. The organic layer was washed with saturated
NaCl, dried over MgSO4, concentrated, and chromatographed
on silica gel with 1:19 ethyl acetate:ligroin to yield a mixture
(0.36 g) which NMR showed to be 15 and 11a in an 86:14 ratio
(adjusted yield of 15: 0.310 g, 57%). Recrystallization from
methanol gave pure 15 (mp 93-95 °C): IR (KBr) 1602, 1301,
(3H, t), 1.07-1.25 (2H, m), 1.29-1.39 (2H, m), 1.88 (3H, s),
1.96-2.06 (2H, d and superimposed m), 2.37 (3H, s), 2.50 (1H,
d, J ) 14.8 Hz), 2.63-2.73 (1H, m), 6.87-7.24 (8H, m); 13C
NMR (CDCl3) δ -0.5 (q), 13.8 (q), 21.5 (q), 23.1 (t), 23.8 (q),
25.7 (t), 25.8 (t), 36.4 (t), 71.5 (s), 123.7 (d), 127.8 (d), 128.7
(d), 130.4 (d), 131.5 (s), 131.6 (d), 132.0 (d), 132.6 (s), 143.6
(s), 144.0 (s); MS(EI) m/e (relative intensity) 247.19 (16), 73.05
(100). Recrystallization of the product from methanol gave
an analytical sample of 11e (mp 73.5-77 °C). Anal. Calcd
for C23H34O2SSi: C, 68.60; H, 8.51. Found: C, 68.85; H, 8.58.
[o-[1-Allyl-1-(p -t olylsu lfon yl)-3-b u t e n yl]b e n zyl]t r i-
m eth ylsila n e (11f). Procedure B (Table 2), alkylation of 3
using n-BuLi and allyl bromide, followed by n-BuLi and allyl
bromide resulted in an oil which on chromatography on silica
gel using petroleum ether/ethyl acetate as developer gave 11f,
yield 75%: IR (neat) 1637, 1597, 1301, 1248, 1145, 1083, 847
1
1245, 1182, 1145, 1121 cm-1; H NMR (CDCl3) δ -0.06 (9H,
s), 1.66-1.77 (4H, d and superimposed d), 2.11 (1H, d, J )
14.4 Hz), 2.27 (3H, s), 2.34 (3H, s), 4.53 (1H, q), 6.85-7.31
(6H, m), 7.62 (1H, d); 13C NMR (CDCl3) δ -1.7, 15.0, 20.0, 21.3,
23.4, 60.5, 124.4, 126.8, 128.2, 128.8, 129.4, 130.1, 131.8, 132.6,
133.1, 139.3, 140.6, 144.2; MS(EI) m/e (relative intensity)
191.12 (97), 73.05 (100). R,R-Dimethyl sulfone 11a was formed
in 9% yield as judged by NMR.
1
cm-1; H NMR (CDCl3) δ 0.08 (9H, s), 2.35 (3H, s), 2.48 (2H,
s), 3.11 (2H, dd, J ) 15.5, 7.2 Hz), 3.39 (2H, dd, J ) 15.6, 6.2
Hz), 5.0-5.2 (4H, m), 5.79-5.95 (2H, m), 6.76-6.90 (2H, m),
7.03-7.18 (6H, m); 13C NMR (CDCl3) δ -0.2, 21.5, 26.7, 37.8,
73.3, 119.0, 123.5, 127.9, 128.7, 130.2, 131.6, 132.1, 132.5,
132.7, 143.7, 144.1.
Tr im eth yl[o-[1-m eth yl-1-(2,4-xylylsu lfon yl)eth yl]ben -
zyl]sila n e (20). A mixture of 11a (2.00 g, 5.55 mmol), THF
(40 mL), and n-BuLi (3.0 mL, 7.1 mmol, 2.35 M in hexane)
was stirred 2 h at -78 °C, and then methyl iodide (0.43 mL,
6.9 mmol) was added. The solution was stirred at -78 °C for
30 min and then warmed to room temperature. The mixture
changed from red-orange to colorless. After being stirred at
room temperature 2 h, the mixture was processed as for 15
and concentrated. Chromatography on silica gel using 1:19
ethyl acetate:ligroin yielded solid 20 (1.59 g, 76%, mp 60-64
Tr im et h yl[o-[1-m et h yl-1-(p -t olylsu lfon yl)-3-b u t en yl]-
ben zyl]sila n e (11g). Procedure B (Table 2), alkylation of 3
using n-BuLi and allyl bromide followed by n-BuLi and methyl
iodide, workup, and then chromatography gave 11g, a colorless
oil, yield 82%: IR (neat) 1640, 1600, 1310, 1255, 1150, 850
1
cm-1; H NMR (CDCl3) δ 0.03 (9H, s), 1.86 (3H, s), 2.15 (1H,
d, J ) 14.9 Hz), 2.39 (3H, s), 2.55 (1H, d, J ) 14.8 Hz), 2.75
(1H, dd, J ) 14.4, 8.6 Hz), 3.55 (1H, dd, J ) 14, 4.5 Hz), 5.05
(1H, br d), 5.17 (1H, br d), 5.40-5.56 (1H, m), 6.86-7.27 (8H,
m); 13C NMR (CDCl3) δ -0.4, 21.5, 23.6, 26.0, 41.1, 70.5, 119.4,
123.7, 128.0, 128.8, 130.3, 131.3, 131.7, 132.0, 132.1, 132.5,
143.6, 144.2; HRMS calcd for C22H30O2SSi 386.1736, found
386.1697. Anal. Calcd for C22H30O2SSi: C, 68.34; H, 7.82.
Found: C, 68.00; H, 7.71.
°C): IR (KBr) 1600, 1290, 1250, 1176, 1152, 1111, 849 cm-1
;
1H NMR (CDCl3) δ 0.04 (9H, s), 1.89 (3H, s), 1.91 (6H, s), 2.33
(3H, s), 2.45 (2H, s), 6.85-6.90 (2H, m), 6.98-7.04 (3H, m),
7.11-7.17 (1H, m), 7.58 (1H, d); 13C NMR (CDCl3) δ -0.5, 19.7,
21.2, 26.2, 26.6, 68.6, 123.9, 126.2, 128.0, 130.5, 130.8, 132.1,
133.1, 133.9, 141.1, 143.2, 144.0; MS(EI) m/e (relative inten-
sity), 205.13 (53), 73.04 (100). Recrystallization of 20 from
ligroin gave an analytical sample (mp 63-65 °C). Anal. Calcd
Tr im et h yl[o-[1-m et h yl-1-(p -t olylsu lfon yl)-5-h exen yl]-
ben zyl]sila n e (11h ). Procedure B (Table 2), alkylation of 3
with n-BuLi and 5-bromo-1-pentene followed by n-BuLi and

2082 J . Org. Chem., Vol. 63, No. 7, 1998
Lenihan and Shechter
for C21H30O2SSi: C, 67.33; H, 8.07. Found: C, 67.29; H, 8.04.
2-(p-Tolylsu lfon yl)-2-[r-(tr im eth ylsilyl)-o-tolyl]acetoph e-
n on e (21a ). To 3 (5.00 g, 15.0 mmol) in THF (100 mL) at
-78 °C was added n-BuLi (6.9 mL, 15.9 mmol, 2.30 M in
hexane). After being warmed to room temperature, the
mixture was cooled to -78 °C, reacted with benzoyl chloride
(3.5 mL, 30 mmol), stirred at -78 °C for 30 min, and then
treated with 10% HCl (20 mL).19 The mixture was then
worked up as for 15 and concentrated. The solid obtained was
recrystallized from methanol to give pure 21a (4.62 g, 70%,
mp 132-133 °C): IR (KBr) 1682, 1594, 1320, 1274, 1220, 1145,
cal sample. Anal. Calcd for C32H32O4SSi: C, 71.08; H, 5.96;
S, 5.93. Found: C, 70.66; H, 5.92; S, 5.84.
Gen er a l P r oced u r e
C (Ta b le 3) for R ea ct ion s of
Mon oa lk yla ted Su lfon es w ith TBAF . o,r-Dim eth ylben -
zyl p-Tolyl Su lfon e (27a ). A solution of 1 M TBAF in
acetonitrile (2.15 mL, 2.15 mmol) was added in 40 min to 10a
(0.479 g, 1.38 mmol) in acetonitrile (5 mL). The mixture was
diluted with water and extracted with dichloromethane. The
organic phase was dried with MgSO4 and concentrated to a
solid which on recrystallization from 1:4 ethyl acetate:ligroin
yielded 27a as a white solid (0.223 g). A second crop of 27a
(0.032 g) was obtained (total yield 67%). The spectroscopic
1
846 cm-1; H NMR (CDCl3) δ -0.02 (9H, s), 2.20 (1H, d, J )
1
properties of 27a : IR (KBr) 1600, 1315, 1150 cm-1; H NMR
14.7 Hz), 2.32 (1H, d, J ) 14.7 Hz), 2.39 (3H, s), 6.54 (1H, s),
6.89-6.98 (1H, m), 7.07-7.22 (4H, m), 7.33-7.57 (6H, m),
7.84-7.88 (2H, m); 13C NMR (CDCl3) δ -0.9, 21.6, 22.5, 70.9,
124.4, 125.5, 128.6, 128.7, 128.9, 129.7, 130.3, 130.5, 133.6,
134.0, 136.7, 141.2, 144.9, 191.3; MS(EI) m/e (relative inten-
sity) 281.13 (11), 265.10 (7), 208.08 (19), 105.03 (41), 91.05 (20),
73.04 (100); HRMS calcd for C25H28O3SSi 436.1528, found
436.1547. Recrystallization from ligroin yielded an analytical
sample. Anal. Calcd for C25H28O3SSi: C, 68.77; H, 6.46.
Found: C, 68.49; H, 6.45.
(CDCl3) δ 1.72 (3H, d, J ) 7.1 Hz), 2.02 (3H, s), 2.39 (3H, s),
4.53 (1H, q, J ) 7.1 Hz), 7.02-7.45 (4H, m); 13C (CDCl3) δ 14.8,
19.4, 21.5, 60.8, 126.2, 128.1, 128.4, 129.2, 130.3, 132.4, 134.4,
137.6, 144.5; MS(EI) m/e (relative intensity) 119.08 (100),
104.07 (15), 91.06 (19); HRMS calcd for C16H18O2S 274.1027,
found 274.1027. The first crop on crystallization from 1:4 ethyl
acetate:ligroin and from 2:1 ligroin:benzene melted at 146-
147 °C. Anal. Calcd for
Found: C, 69.77; H, 6.81.
C16H18O2S: C, 70.04; H, 6.62.
p-Tolyl 1-o-Tolyl-3-bu ten yl Su lfon e (27b). Procedure C
(Table 3), 10b in acetonitrile, with TBAF in acetonitrile yielded
a white solid which recrystallized from ligroin to give 27b, yield
3,3-Dim eth yl-1-(p-tolylsu lfon yl)-1-[r-(tr im eth ylsilyl)-o-
tolyl]-2-bu ta n on e (21b). n-BuLi (1.20 mL, 1.62 mmol, 1.35
M in hexane) was added to 3 (0.496 g, 1.49 mmol) in THF (10
mL) at -78 °C. The mixture was warmed to room temperature
and cooled to -78 °C, and trimethylacetyl chloride (0.20 mL,
1.6 mmol) was added. The solution, after warming to room
temperature, became colorless. TLC showed that some 3
remained. The mixture was again treated with n-BuLi (1.20
mL) and trimethylacetyl chloride (0.21 mL) as before. The
mixture was processed as for 15 and concentrated. Crystal-
lization from 1:19 ethyl acetate:ligroin yielded initial 3 (54 mg).
Chromatography of the mother liquor on TLC grade silica gel
using 1:19 ethyl acetate:ligroin yielded 21b (0.427 g, 69%) as
a white solid (mp 54-77 °C): IR (KBr) 1712, 1597, 1318, 1249,
1
62%: IR (KBr) 1645, 1600, 1315, 1295, 1150 cm-1; H NMR
(CDCl3) δ 1.91 (3H, s), 2.38 (3H, s), 2.82-2.95 (1H, m), 3.12-
3.22 (1H, m), 4.45 (1H, dd, J ) 4.0, 11.4 Hz), 4.90-4.95 (1H,
br d), 4.98-5.06 (1H, br d), 5.40-5.56 (1H, m), 6.98-7.47 (8H,
m); 13C (CDCl3) δ 19.4, 21.5, 32.7, 65.5, 118.3, 126.2, 128.2,
128.4, 129.1, 129.2, 130.2, 130.4, 132.9, 134.7, 138.3, 144.5;
MS(EI) m/e (relative intensity), 145.09 (100), 91.06 (36); HRMS
calcd for C18H20O2S 300.1184, found 300.1176. An analytical
sample (mp 84-86 °C) was obtained upon recrystallization
from ligroin. Anal. Calcd for C18H20O2S: C, 71.97; H, 6.71.
Found: C, 71.55; H, 6.89.
1
1150, 852 cm-1; H NMR (CDCl3) δ 0.15 (9H, s), 1.03 (9H, s),
p-Tolyl r-o-Tolylp h en eth yl Su lfon e (27c). Procedure C
(Table 3), 10c in acetonitrile, with TBAF in acetonitrile led to
a solid which on crystallization from 1:4 ethyl acetate:ligroin
gave 27c, yield 70%: IR (KBr) 1600, 1320, 1310, 1300, 1290,
1150, 1095 cm-1; 1H NMR (CDCl3) δ 1.60 (3H, s), 2.37 (3H, s),
3.35 (1H, dd, J ) 13.5, 11.67 Hz), 3.82 (1H, dd, J ) 13.5, 3.17
2.26 (2H, dd), 2.40 (3H, s), 6.11 (1H, s), 6.79-6.92 (2H, m),
7.15-7.25 (5H, m), 7.43-7.48 (1H, br d); MS(EI) m/e (relative
intensity) 332.12 (2), 261.17 (14), 188.12 (71), 73.05 (84), 57.07
(100).
2-(p -Tolylsu lfon yl)-2-[r-(t r im et h ylsilyl)-o-t olyl]p r o-
p iop h en on e (21c). To benzoyl chloride (0.82 mL, 7.1 mmol)
in THF (10 mL) at -78 °C was added in 100 min via cannula
a solution prepared from 10a (0.498 g, 1.44 mmol) and n-BuLi
(1.32 mL, 1.51 mmol, 1.14 M in hexane) in THF (10 mL). The
colorless mixture was warmed to room temperature, stirred
with saturated NaHCO3, and extracted with diethyl ether. The
organic phase was processed and concentrated. The concen-
trate was chromatographed on silica gel using 1:19 ethyl
acetate:petroleum ether as solvent to obtain 21c as a foam
(0.467 g, 72%): 1H NMR δ -0.06 (9H, s), 1.75 (1H, d), 2.11
(3H, s), 2.40 (3H, s), 2.45 (1H, d), 7.05-8.15 (13H, m).
r-(p -Tolylsu lfon yl)-2-[(t r im et h ylsilyl)m et h yl]-r-st il-
ben ol Ben zoa te (22). A mixture of sulfone 21a , THF (7 mL),
3 M NaOH (3 mL), and benzoyl chloride (0.27 mL) was stirred
for 1.5 h. When TLC showed that reaction was complete, the
mixture was processed routinely and concentrated to a solid.
Recrystallization from methanol yielded 22 (0.520 g, 84%, mp
167-170 °C): IR (KBr) 1746, 1614, 1597, 1315, 1246, 1209,
Hz), 4.62 (1H, dd, J ) 11.6, 3.17 Hz), 6.82-7.73 (13H, m); 13
C
NMR (CDCl3) δ 19.1, 21.5, 34.7, 67.4, 126.1, 126.5, 128.2, 128.3,
128.4, 128.8, 128.9, 129.2, 130.0, 130.4, 134.8, 136.9, 138.2,
144.5; MS(EI) m/e (relative intensity), 195.12 (65), 117.07 (16),
91.06 (15). Recrystallizations from 1:4 ethyl acetate:ligroin
gave an analytical sample (mp 155-157 °C). Anal. Calcd for
C
22H22O2S: C, 75.40; H, 6.32. Found: C, 75.04; H, 6.58.
o-Meth ylben zyl-r-2-p r op yl p-Tolyl Su lfon e (27d ). Pro-
cedure C (Table 3), 10d in acetonitrile with TBAF in acetoni-
trile, and chromatography on silica gel using 1:19 ethyl acetate:
petroleum ether gave 27d as an oil which solidified, yield 69%
(mp 83-84 °C): IR (KBr) 1597, 1313, 1286, 1139 cm-1 1H
;
NMR (CDCl3) δ 0.89 (3H, d, J ) 6.8 Hz), 1.35 (3H, d, J ) 6.6
Hz), 1.83 (3H, s), 2.29 (3H, s), 2.78-2.93 (1H, m), 4.20 (1H, d,
J ) 8.5 Hz), 6.85 (1H, d), 7.00-7.22 (3H, m), 7.32 (2H, d), 7.66
(1H, dd); 13C NMR (CDCl3) δ 19.6, 21.1, 21.4, 22.1, 30.0, 71.6,
126.1, 128.00, 128.5, 128.7, 130.0, 131.9, 136.5, 137.5, 143.7;
MS(EI) m/e (relative intensity) 147.12 (57), 105.07 (100), 91.05
(13), 55.05 (19).
1151, 1094, 854 cm-1 1H NMR (CDCl3) δ 0.04 (9H, s), 2.15
;
r,r-Dim eth yl-o-qu in od im eth a n e (29a ) a n d Its Cycloa d -
d it ion w it h Acr ylon it r ile. 1,2,3,4-Tet r a h yd r o-1,1-d i-
m eth yl-2-n a p h th on itr ile (35). To 11a (0.401 g, 1.11 mmol)
and acrylonitrile (2.9 mL, 44 mmol) in acetonitrile (8 mL) was
added TBAF (2.2 mL, 2.1 mmol, 1 M in acetonitrile) in
acetonitrile (8 mL) over 60 min. The mixture was processed
as for 7 and concentrated. Column chromatography on silica
gel using 1:1 dichloromethane:petroleum ether (bp 35-60 °C)
yielded styrene 36 (25 mg, 17%). The second eluent contained
nitrile 35 as an oil (111 mg, 54%): IR (neat) 2238, 1491, 762
cm-1; 1H NMR (CDCl3) δ 1.48 (3H, s), 1.50 (3H, s), 2.05-2.27
(2H, m), 2.82 (1H, dd, J ) 3.7, 9.5 Hz), 2.87-3.12 (2H, m),
7.05-7.36 (4H, m); 13C NMR (CDCl3) δ 22.9, 28.2, 28.3, 30.2,
36.0, 39.5, 121.0, 126.3, 126.3, 126.5, 129.1, 133.3, 142.2; NOE
(1H, d, J ) 14.9 Hz), 2.31 (1H, d, J ) 14.9 Hz), 2.38 (3H, s),
7.05-7.28 (11H, m), 7.52 (2H, t), 7.64-7.70 (3H, m), 8.10-
8.13 (2H, d); 13C NMR (CDCl3) δ -0.4 (q), 21.5 (q), 23.0 (t),
124.3 (d), 128.0 (d), 128.2 (d), 128.4 (d), 128.5 (d), 128.8 (s),
129.1 (d), 129.1 (d), 129.5 (d), 129.8 (d), 130.1 (s), 130.4 (d),
132.7 (d), 133.6 (s), 133.8 (d), 134.2 (s), 138.8 (s), 142.7 (s),
143.9 (s), 152.9 (s), 163.6 (s); MS(EI) m/e (relative intensity)
525.16 (2), 419.15 (12), 191.09 (9), 105.03 (100), 77.04 (20),
73.05 (15); HRMS calcd for C32H32O4SSi 540.1791, found
540.1801. Recrystallization from methanol yielded an analyti-
(19) Allowing the mixture to warm to room temperature without
HCl treatment caused formation of a small amount of 22 which is
difficult to remove by crystallization.

Synthesis of Quinodimethanes
J . Org. Chem., Vol. 63, No. 7, 1998 2083
differences with irradiation of the methyl singlets at δ 1.48
and 1.50 gave enhancements at δ 2.0-2.3 (6%), δ 2.82 (8%),
and δ 7.34 (16%); MS(EI) m/e (relative intensity) 185.12 (42),
170.09 (100), 143.08 (64); HRMS calcd for C13H15N 185.1204,
found 185.1204. The third eluent contained 33a as a solid (45
mg, 14%).
(CDCl3) δ 28.3 (q), 29.6 (q), 33.3 (t), 37.1 (s), 39.9 (d), 51.5 (q),
51.9 (q), 53.4 (d), 126.0 (d), 126.5 (d), 126.7 (d), 128.6 (d), 132.5
(s), 144.0 (s), 173.8 (s), 175.4 (s); NOE differences with
irradiation at δ 1.53 gave enhancements of a doublet at δ 2.93
(12.8%) and a doublet of doublets at δ 7.36 (15.0%); NOE
differences with irradiation at δ 1.21 gave enhancements of a
multiplet at δ 3.08-3.24 (12.6%), a multiplet at δ 7.0-7.3
(5.6%), and a doublet of doublets at δ 7.36 (7.9%); MS(EI) m/e
(relative intensity) 276 (5), 245 (9), 244 (13), 216 (42), 201 (15),
157 (75); HRMS calcd for C16H20O4 276.1361, found 276.1366.
r,r-Dim et h yl-o-q u in od im et h a n e (29a ) w it h Diet h yl
Fu m ar ate. Dieth yl tr a n s-1,2,3,4-Tetr ah ydr o-1,1-dim eth yl-
2,3-n a p h th a len ed ica r boxyla te (43b). A solution of TBAF
(4.2 mL, 4.2 mmol, 1 M in acetonitrile) was added in 60 min
to 11a (1.00 g, 2.77 mmol) and diethyl fumarate (0.91 mL, 5.54
mmol) in acetonitrile (15 mL). The reaction mixture was
chromatographed on silica gel using 1:19 ethyl acetate:ligroin
as solvent. The first eluent contained 43b as an oil (0.49 g,
1,2,3,4-Tet r a h yd r o-1,1-d im et h yl-4-oxo-2-n a p h t h on i-
tr ile (38). To nitrile 35 (0.109 g, 0.59 mmol) in glacial acetic
acid (16 mL) was added a 10% solution of chromium trioxide
in glacial acetic acid over 25 min (1.7 mL, 2.7 mmol).20 After
20 min of stirring, the mixture was worked up as for 35 and
concentrated. Chromatography on TLC grade silica gel using
dichloromethane as eluent yielded 38 as a liquid (0.0377 g,
1
32%): IR (neat) 2240, 1690, 1600, 1300, 775 cm-1; H NMR
(CDCl3) δ 1.55 (3H, s), 1.62 (3H, s), 3.01-3.04 (2H, two
superimposed d, J ) 7.2, 8.4 Hz), 3.25 (1H, dd, J ) 7.0, 8.5
Hz), 7.34-7.64 (3H, m), 8.04 (1H, dd); MS(EI) m/e (relative
intensity) 199.10 (85), 184.07 (100), 146.07 (53), 131.05 (47),
91.05 (88); HRMS calcd for C13H13NO 199.0997, found 199.0977.
r,r,-Dim et h yl-o-q u in od im et h a n e (29a ) a n d It s Cy-
cloa d d ition s w ith Meth yl Acr yla te. Meth yl 1,2,3,4-Tet-
r a h yd r o-1,1-d im eth yl-2-n a p h th oa te (39a ) a n d Meth yl
1
58%): IR (neat) 1735 cm-1; H NMR (CDCl3) δ 1.22 (3H, s),
1.29 (3H, t), 1.30 (3H, t), 1.55 (3H, s), 2.82-2.94 (2H, m and
superimposed d, J (of doublet) ) 11.7 Hz), 3.07-3.21 (2H, m),
4.14-4.28 (4H, m), 7.03-7.23 (3H, m), 7.36 (1H, dd); 13C NMR
(CDCl3) δ 14.1, 14.2, 28.2, 29.6, 33.4, 37.1, 40.0, 53.4, 60.3,
60.6, 125.9, 126.5, 126.6, 128.2, 132.6, 144.1, 173.2, 174.9; NOE
differences with irradiation at δ 1.22 gave enhancements at δ
3.0-3.2 (11.7%) and δ 7.36 (8.9%); NOE differences with
irradiation at δ 1.54 resulted in enhancements of the doublet
at δ 2.90 (12.2%) and the doublet at δ 7.36 (15.7%); MS(EI)
m/e (relative intensity) 304.17 (3), 259.13 (12), 258.12 (8),
157.10 (100), 143.09 (41); HRMS calcd for C18H24O4 304.1674,
found 304.1668.
1,2,3,4-Tetr a h yd r o-4,4-d im eth yl-2-n a p h th oa te (40a ).
A
solution of 1 M TBAF in acetonitrile (2.8 mL, 2.8 mmol) was
added in 60 min to 11a (0.504 g, 1.40 mmol) and methyl
acrylate (1.9 mL, 21 mmol) in acetonitrile (6 mL). The mixture
was worked up and concentrated. Column chromatography
(TLC grade silica gel, 1.19 ethyl acetate:ligroin) gave styrene
36 (22 mg, 12%) as the first eluent: IR (neat) 900, 770 cm-1
;
1H NMR (CDCl3) δ 2.05 (3H, br s), 2.33 (3H, s), 4.86 (1H, br
s), 5.20 (1H, br s), 7.12-7.26 (4H, m).
The next eluent contained 33a (0.11 g, 14%, mp 124-127
°C): IR (neat) 1594, 1285, 1152, 1129 cm-1; 1H NMR (CDCl3)
δ 1.92 (6H, s), 2.39 (3H, s), 2.45 (3H, s), 6.99-7.32 (8H, m);
13C NMR (CDCl3) δ 21.5, 24.3, 25.5, 67.8, 125.4, 128.5, 128.8,
130.3, 130.7, 132.3, 133.3, 135.1, 139.5, 144.2; MS(EI) m/e
(relative intensity) 133.09 (37), 133.01 (100), 105.07 (37).
TBAF -In d u ced Elim in a tion of 11a in th e P r esen ce of
Dieth yl Ma lea te. A solution of TBAF (2.8 mL, 2.8 mmol, 1.0
M in acetonitrile) was added in 90 min to 11a (0.500 g, 1.39
mmol) and diethyl maleate21 (0.45 mL, 2.77 mmol) in aceto-
nitrile (10 mL). After an hour, additional TBAF (0.5 mL) was
added. After routine workup, the mixture was concentrated.
Chromatography on silica gel using 1:19 ethyl acetate:ligroin
yielded diethyl fumarate (181 mg, 38%). The next eluent
contained 43b (133 mg, 32%). NMR indicated that the product
is identical to that from cycloaddition with diethyl fumarate.
The next eluent contained recovered diethyl maleate (162 mg,
34%).
The second eluent, a liquid, contained isomers 39a and 40a
(123 mg, 40%) in a 3:1 ratio as determined by 1H NMR: IR
(neat) 1738, 1731 cm-1; 1H NMR (CDCl3) δ 1.3-1.6 (6H), 2.0-
2.3 (2H), 2.65-3.15 (3H), 3.7-3.8 (3H), 7.0-7.4 (4H); MS(EI)
m/e (relative intensity) 218.13 (9), 203.11 (9), 186.11 (11),
158.11 (19), 143.09 (83); HRMS calcd for C14H18O2 218.1307,
found 218.1341. The third eluent contained 33a (58 mg, 14%).
E t h yl 1,2,3,4-Tet r a h yd r o-1,1-d im et h yl-2-n a p h t h oa t e
(39b) a n d Eth yl 1,2,3,4-Tetr a h yd r o-4,4-d im eth yl-2-n a p h -
th oa te (40b). To 11a (492 mg, 1.37 mmol) and ethyl acrylate
(2.2 mL, 21 mmol) in acetonitrile (5 mL) was added TBAF (2.75
mL, 2.8 mmol, 1 M in acetonitrile) over 60 min. After workup,
the material was chromatographed on TLC grade silica gel
using 1:19 ethyl acetate:ligroin. The first eluent was styrene
derivative 36 (25 mg, 14%). The next eluent, an oil, consisted
of isomers 39b and 40b in a 3:1 ratio (141 mg, 47%): IR (neat)
1
1731 cm-1; H NMR (CDCl3) δ 1.2-1.6 (9H, m), 1.7-2.2 (2H,
m), 2.6-3.1 (3H, m), 4.1-4.4 (2H, m), 7.0-7.5 (4H, m); MS(EI)
m/e (relative intensity) 232.15 (30), 217.12 (11), 186.10 (23),
159.12 (26), 158.11 (51), 143.08 (100); HRMS calcd for C15H20O2
232.1463, found 232.1458. The third eluent was 33a (46 mg,
12%).
Cesiu m F lu or id e-In d u ced Elim in a tion of 11a in th e
P r esen ce of Dieth yl Ma lea te. Silyl sulfone 11a (0.500 g,
1.39 mmol), acetonitrile (10 mL), and diethyl maleate (0.45
mL, 2.8 mmol) were added to cesium fluoride (0.42 g, 2.8 mmol)
in a flame-dried flask. After 3 weeks of stirring under argon,
the mixture was processed routinely and concentrated. Chro-
matography on silica gel using 1:19 ethyl acetate:petroleum
ether as elutent yielded diethyl fumarate as the first eluent
(0.18 g, 36%). The next eluent contained 43b (0.249 g, 59%).
Dim eth yl tr a n s-1,1-Dieth yl-1,2,3,4-tetr ah ydr o-2,3-n aph -
th a len ed ica r boxyla te (48a ). TBAF (1.9 mL, 1.9 mmol, 1.0
M in acetonitrile) was added over 45 min to 11b (0.359 g, 924
mmol) and dimethyl fumarate (0.53 g, 3.7 mmol) in acetonitrile
(7 mL). The mixture was worked up routinely and concen-
trated. Dimethyl fumarate (0.34 g) was removed by crystal-
lization from methanol. The mother liquor was concentrated
and chromatographed on silica gel using 1:19 ethyl acetate:
ligroin as solvent. The first eluent, a liquid, contained styrene
derivatives 49a and 49b in a 3:1 ratio (38 mg, 26%): IR (KBr)
759, 730 cm-1; MS(EI) m/e (relative intensity) 160.13 (65),
145.10 (41), 131.09 (100), 91.06 (44); HRMS calcd for C12H16
Cycloaddition of r,r-Dim eth yl-o-qu in odim eth an e (29a)
w ith Dim eth yl F u m a r a te. Dim eth yl tr a n s-1,2,3,4-Tet-
r ah ydr o-1,1-dim eth yl-2,3-n aph th alen edicar boxylate (43a).
To 11a (0.499 g, 1.38 mmol) and dimethyl fumarate (0.40 g,
2.77 mmol) in acetonitrile (8 mL) in 40 min was added TBAF
(2.8 mL, 2.8 mmol, 1 M in acetonitrile). The mixture was
stirred for 3 h and processed routinely. The organic product
was concentrated to an oily solid, dissolved in hot methanol,
and cooled to 0-5 °C to crystallize the dimethyl fumarate. The
mother liquor was concentrated and chromatographed on silica
gel using 1:19 ethyl acetate:ligroin as solvent to yield an oil
(0.258 g) which NMR showed to be 43a contaminated with 15
mol % 33a (adjusted yield of 43a : 0.22 g, 57%; yield of 33a :
40 mg, 10%). Preparative GC yielded pure 43a : IR (neat) 1740
cm-1; 1H NMR (CDCl3) δ 1.21 (3H, s), 1.53 (3H, s), 2.83-2.95
(2H, m and superimposed d, J (of doublet) ) 11.5 Hz), 3.09-
3.25 (2H, m), 7.03-7.24 (3H, m), 7.36 (1H, dd); 13C NMR
1
160.1252, found 160.1257; H NMR of isomer 49a (CDCl3) δ
(20) A solution of CrO3 in acetic acid and water oxidizes the 1
position of tetrahydronaphthalenes. Burnham, J . W.; Duncan, W. P.;
Eisenbraun, E. J .; Keen, G. W.; Hamming, M. C. J . Org. Chem. 1974,
39, 1416.
(21) Commercial diethyl maleate is contaminated with
amount of diethyl fumarate. In the present work, the diethyl maleate
was purified by chromatography and distillation.
a small

2084 J . Org. Chem., Vol. 63, No. 7, 1998
Lenihan and Shechter
1.04 (3H, t), 1.42 (3H, dt, J ) 6.7, 1.2 Hz), 2.25 (3H, s), 2.3-
2.35 (2H, m), 5.59 (1H, qt, J ) 6.7, 1.2 Hz), 7.0-7.3 (4H, m);
1H NMR of isomer 49b (CDCl3) δ 0.93 (3H, t), 1.82 (3H, d, J )
6.8 Hz), 2.31 (3H, s), 2.4-2.5 (2H, m), 5.35 (1H, q, J ) 6.8
Hz), 7.0-7.3 (4H, m).
2-n a p h th oa tes (60). To 11c (497 mg, 1.33 mmol) and methyl
acrylate (1.8 mL, 20 mmol) in acetonitrile (5 mL) was added
TBAF (2.7 mL, 2.7 mmol, 1 M in acetonitrile) over 40 min.
After workup, the material was chromatographed on TLC
grade silica gel using 1:19 ethyl acetate:ligroin as solvent.
Styrenes 51a and 51b (70 mg, 36%) were in the first eluent.
The next eluent, an oil, contained 60 as a mixture of isomers
(92 mg, 30%): IR (neat) 1733, 1205, 1156, 758 cm-1; 1H NMR
(CDCl3) δ 0.6-0.9 (3H, m), 1.2-1.5 (3H, m), 1.7-2.3 (4H, m),
2.6-3.0 (3H, m), 3.7-3.8 (3H, m), 7.0-7.4 (4H, m); MS(EI)
m/e (relative intensity) 232.15 (4), 203.11 (36), 143.09 (100);
HRMS calcd for C15H20O2 232.1463, found 232.1473. The third
eluent contained 33c (51 mg, 13%).
The next eluent was a mixture (69 mg) of 48a and 33b and
a small amount of dimethyl fumarate. The mixture, as judged
by 1H NMR, contained 59 mg of 48a (21%) and 7 mg of 33b
(2%). The spectral data of 48a : IR (KBr) 1735 cm-1; 1H NMR
(CDCl3) δ 0.66 (3H, t), 0.72 (3H, t), 1.57 (1H, sextet), 1.67 (1H,
sextet), 1.84 (1H, sextet), 1.97 (1H, sextet), 2.77 (1H, dd, J )
12.2, 16.0 Hz), 3.06 (1H, dd, J ) 4.8, 16.0 Hz), 3.18 (1H, d, J
) 12.2 Hz), 3.30 (1H, td, J ) 12.2, 4.8 Hz), 3.72 (3H, s), 3.73
(3H, s), 7.00-7.25 (4H, m); MS(EI) m/e (relative intensity)
243.10 (50), 215.11 (57), 183.08 (35), 143.08 (100), 129.07 (52);
HRMS calcd for C18H24O4 304.1675, found 304.1668.
Dieth yl tr a n s-1,1-Dieth yl-1,2,3,4-tetr a h yd r o-2,3-n a p h -
th a len ed ica r boxyla te (48b). TBAF (1.8 mL, 1.8 mmol) was
added over 45 min to 11b (0.351 g, 903 mmol) and diethyl
fumarate (0.59 mL, 3.6 mmol) in acetonitrile (7 mL). The
mixture was processed as for 48a and concentrated. Chro-
matography on silica gel using 1:19 ethyl acetate:ligroin
yielded a 4:1 mixture of 49a and 49b as the first eluent (67
mg, 46%).
Eth yl 1-Eth yl-1,2,3,4-tetr ah ydr o-1-m eth yl-2-n aph th oate
a n d Eth yl 4-Eth yl-1,2,3,4-tetr a h yd r o-4-m eth yl-2-n a p h -
th oa te (61). To 11c (506 mg, 1.35 mmol) and ethyl acrylate
(2.2 mL, 20 mmol) in acetonitrile (5 mL) was added TBAF (2.7
mL, 2.7 mmol, 1 M in acetonitrile) over 50 min. After workup,
the material was chromatographed on TLC grade silica gel
using 1:2 dichloromethane:ligroin as solvent. The first eluent
contained styrenes 51a and 51b (70 mg, 35%). The next eluent
yielded isomers 61 (93 mg, 28%) as an oil: IR (neat) 1731 cm-1
;
1H NMR (CDCl3) δ 0.7-1.0 (3H, m), 1.2-1.5 (6H, m), 1.6-2.3
(4H, m), 2.6-3.1 (3H, m), 4.1-4.3 (2H, m), 7.0-7.4 (4H, m);
MS(EI) m/e (relative intensity) 246.16 (5), 217.13 (38), 143.09
(100); HRMS calcd for C16H22O2 246.1620, found 246.1618.
Cycloaddition s of r-Eth yl-r-m eth yl-o-qu in odim eth an es
(29c,d) an d Dim eth yl Fu m ar ate; Dim eth yl 1-Eth yl-1,2,3,4-
t e t r a h yd r o-1-m e t h yl-2,3-n a p h t h a le n e d ica r b oxyla t e s
(62a ,b). TBAF (3.0 mL, 3.0 mmol, 1.0 M in acetonitrile) was
added to 11c (0.749 g, 2.00 mmol) and dimethyl fumarate (0.58
g, 4.02 mmol) in acetonitrile (12 mL) in 1 h. The mixture was
then worked up routinely and concentrated. Dimethyl fuma-
rate was removed via crystallization from methanol, and the
mother liquor was concentrated and chromatographed on TLC
grade silica gel using 1:19 ethyl acetate:ligroin as solvent. The
first eluent yielded styrenes 51a and 51b in a 4:1 ratio (23
mg, 8%). The second eluent yielded an oil (0.32 g) which NMR
showed to be diastereomers 62a and 62b in a 58:42 ratio
contaminated with 15% 33c (adjusted yield of 62a and 62b,
0.27 g, 47%; yield of 33c, 48 mg, 8%). Preparative GC yielded
The next eluent contained mostly diethyl fumarate, which
after removal by distillation (70 °C, 0.65 Torr), yielded 48b as
1
an oil (32 mg, 23%): IR (neat) 1731 cm-1; H NMR (CDCl3) δ
0.67 (3H, t), 0.72 (3H, t), 1.25-1.32 (6H, m), 1.54-1.73 (2H,
m), 1.81-2.05 (2H, m), 2.77 (1H, dd, J ) 12.2, 16.0 Hz), 3.06
(1H, dd, J ) 4.8, 16.0 Hz), 3.15 (1H, d, J ) 12.2 Hz), 3.27 (1H,
td, J ) 12.2, 4.8 Hz), 4.11-4.27 (4H, m), 7.04-7.20 (4H, m);
13C NMR (CDCl3) δ 8.4, 10.0, 14.1, 32.5, 33.5, 34.9, 40.3, 44.5,
48.0, 60.3, 60.6, 125.7, 126.4, 126.8, 128.5, 135.5, 139.2, 173.4,
175.3; MS(EI) m/e (relative intensity) 258.16 (14), 257.12 (18),
229.12 (54), 185.13 (43), 157.10 (82), 129.07 (100). The third
eluent contained 33b (R and R′ ) Et, 14 mg, 5%).
Cycloa d d ition s of Acr ylon itr ile to r-Eth yl-r-m eth yl-
o-qu in od im eth a n es (29c-d ). 1-Eth yl-1,2,3,4-tetr a h yd r o-
1-m eth yl-2-n a p h th on itr ile (54a -b). TBAF (2.1 mL, 2.1
mmol, 1 M in acetonitrile) in acetonitrile (8 mL) was added in
40 min to 11c (0.402 mg, 1.07 mmol) and acrylonitrile (2.8 mL,
42 mmol) in acetonitrile (8 mL). The mixture was processed
routinely and concentrated. Column chromatography on silica
gel using 1:1 dichloromethane:petroleum ether (bp 35-60 °C)
yielded as the first eluent a mixture of styrenes 51a and 51b
in an 85:15 ratio (45 mg, 29%) whose spectral data are
consistent with that reported.22
a pure mixture of 62a and 62b, an oil: IR (neat) 1740 cm-1
;
1H NMR (CDCl3) δ 0.6-0.8 (3H, m), 1.19, 1.48 (3H, two s in
55:45 ratio), 1.5-1.8 (1H, m), 1.9-2.0 (1H, q), 2.8-3.5 (4H,
m), 3.7 (6H, m), 7.0-7.3 (4H, m); MS(EI) m/e (relative
intensity) 290.16 (8), 259.14 (14), 258.13 (20), 230.13 (53),
229.09 (41), 201.10 (100); HRMS calcd for C17H22O4 290.1518,
found 290.1562. The mixture of diastereomers was chromato-
graphed over silica gel (15 g) using 1:19 ethyl acetate:ligroin
as solvent to obtain an analytical sample. Anal. Calcd for
The second eluent, an oil, contained diastereomers 54a and
54b in a 1:2 ratio (92 mg, 43%): IR (neat) 2236, 758 cm-1
;
MS(EI) m/e (relative intensity) 199.14 (12), 170.10 (100), 143.08
(63); HRMS calcd for C14H17N 199.1361, found 199.1381. The
isomers were separated by GC (10 ft × 0.25 in. Gas chromosorb
Q GE SE30 15%). The compound with a lower retention time
is assigned 54a : 1H NMR (CDCl3) δ 0.73 (3H, t), 1.45 (3H, s),
1.78-2.07 (2H, m), 2.08-2.28 (2H, m), 2.78-2.95 (2H, m),
2.96-3.11 (1H, dd, J ) 3.7, 9.9 Hz), 7.04-7.31 (4H, m); 13C
(CDCl3) δ 8.5 (q), 22.8 (t), 27.9 (q), 28.5 (t), 33.4 (t), 34.7 (d),
39.6 (s), 121.0 (s), 126.1 (d), 126.5 (d), 129.2 (d), 134.5 (s), 140.5
(s). The NOE of 54a upon irradiation at δ 1.45 gave enhance-
ments at δ 0.73 (2%), δ 1.8-2.2 (10%), δ 3.0-3.1 (1%), and δ
7.1-7.3 (6%). The product with the higher retention time is
assigned 54b: 1H NMR (CDCl3) δ 0.98 (3H, t), 1.42 (3H, s),
1.81-2.02 (2H, m), 2.12-2.32 (2H, m), 2.81-2.94 (2H, dd with
superimposed m), 3.06 (1H, dt, J ) 6.5, 17.3 Hz), 7.07-7.31
(4H, m); 13C NMR (CDCl3) δ 9.0, 22.5, 27.0, 27.5, 32.5, 37.8,
38.7, 121.0, 126.1, 126.3, 126.7, 129.3, 133.9, 141.1. The NOE
of 54b with irradiation at δ 1.41 exhibited enhancements at δ
0.98 (5%), δ 1.8-2.1 (4%), δ 2.1-2.3 (2%), δ 2.85-2.95 (dd,
7%), and δ 7.25-7.35 (8%). The third eluent contained 33c
(35 mg, 10%).
C
17H22O4: C, 70.32; H, 7.64. Found: C, 69.95; H, 7.67.
Cycloaddition s of r-Eth yl-r-m eth yl-o-qu in odim eth an es
(29c,d ) w ith Dieth yl F u m a r a te; Dieth y1 Eth yl-1,2,3,4-
t e t r a h yd r o-1-m e t h yl-2,3-n a p h t h a le n e d ica r b oxy-la t e
(63a ,b). To 11c (0.498 g, 1.33 mmol) and diethyl fumarate
(0.44 mL, 2.7 mmol) in acetonitrile (8 mL) was added TBAF
(2.7 mL, 2.7 mmol, 1 M in acetonitrile) in 38 min. After 3 h,
the mixture was worked up and concentrated. The residue
was chromatographed with TLC grade silica gel using 1:19
ethyl acetate:ligroin as solvent. The first eluent contained
styrenes 51a and 51b in a 4:1 ratio (9 mg, 5%).
The second eluent yielded diastereomers 63a and 63b as
an oil in approximately a 55:45 ratio (213 mg, 51%): IR (neat)
1730 cm-1; MS(EI) m/e (relative intensity) 318.18 (5), 273.15
(22), 272.15 (17), 244.15 (54), 215.11 (62), 171.12 (61), 143.09
(100). The isomers were separable by GC. Isomer 63a had
the lower retention time: 1H NMR (CDCl3) δ 0.69 (3H, t), 1.20
(3H, s), 1.29 (6H, t), 1.88-2.05 (2H, m), 2.77-3.04 (2H, m),
3.09-3.20 (2H, m), 4.09-4.26 (4H, m), 7.03-7.31 (4H, m);
NOE differences with irradiation at δ 1.20 gave enhancements
at δ 1.9-2.1 (6.2%), δ 3.1-3.2 (14.4%), δ 4.1-4.3 (2.3%), and
δ 7.2-7.3 (9.3%). Isomer 63b had the higher retention time:
1H NMR (CDCl3) δ 0.73 (3H, t), 1.28 (3H, t), 1.30 (3H, t), 1.50
(3H, s), 1.54-1.79 (2H, m), 2.87 (1H, dd, J ) 11.9, 16.2 Hz),
2.92 (1H, d, J ) 12.1 Hz), 3.15 (1H, dd, J ) 5.8, 16.2 Hz), 3.27-
Met h yl 1-E t h yl-1,2,3,4-t et r a h yd r o-1-m et h yl-2-n a p h -
th oa tes a n d Meth yl 4-Eth yl-1,2,3,4-tetr a h yd r o-4-m eth yl-
(22) Hornback, J . M.; Barrows, R. D. J . Org. Chem. 1982, 47, 4285.

Synthesis of Quinodimethanes
J . Org. Chem., Vol. 63, No. 7, 1998 2085
3.39 (1H, m), 4.12-4.28 (4H, m), 7.06-7.32 (4H, m); NOE
differences with irradiation at δ 1.50 gave enhancements of a
multiplet at δ 1.55-1.8 (3.2%), a doublet at δ 2.92 (16.3%),
and a doublet at δ 7.25-7.35 (14.6%).
rate was removed via crystallization from methanol. The
mother liquor was concentrated and chromatographed on silica
gel with 1:19 ethyl acetate:petroleum ether to obtain diaster-
eomers 70a and 70b (103 mg, 26%) in a 7:1 ratio as judged by
NMR: IR (neat) 1737 cm-1; MS(EI) m/e (relative intensity)
304.17 (1), 273.15 (3), 261.11 (6), 244.14 (4), 229.08 (61), 201.09
(100); HRMS calcd for C18H24O4 304.1674, found 304.1675.
Chromatography by MPLC using Size A (240-10) LiChro-
prep Si60 (40-63 mm) and 1:19 ethyl acetate:petroleum ether
yielded pure 70a as the first eluent: 1H NMR (CDCl3) δ 0.76
(3H, d, J ) 7.0 Hz), 0.91 (3H, d, J ) 7.0 Hz), 1.56 (3H, s), 2.07
(1H, septet, J ) 7.0 Hz), 2.84 (1H, dd, J ) 11.2, 16.6 Hz), 2.91
(1H, d, J ) 12.3 Hz), 3.21 (1H, dd, J ) 16.6, 6.6 Hz), 3.53 (1H,
ddd, J ) 12.3, 11.2, 6.6 Hz), 3.72 (3H, s), 3.73 (3H, s), 7.04-
7.34 (4H, m); 13C NMR (CDCl3) δ 19.3 (q), 19.6 (q), 26.7 (q),
32.7 (t), 36.9 (d), 39.9 (d), 43.5 (s), 51.6 (q), 51.9 (q), 52.7 (d),
126.0 (d), 126.1 (d), 126.9 (d), 128.5 (d), 133.4 (s), 143.0 (s),
174.6 (s), 176.0 (s); NOE differences with irradiation at δ 1.56
gave enhancements at δ 0.76 (7.7%), δ 2.07 (5.5%), δ 2.90 (d,
19.2%), and δ 7.3-7.4 (17.3%).
Elim in a tion of Tr im eth yl[o-[1-(2-p r op en yl)-1-(p-tolyl-
su lfon yl)-3-b u t en yl]b en zyl]sila n e (11f); (E)-4-o-Tolyl-
1,3,6-h ep ta tr ien e (76), a n d (Z)-4-o-Tolyl-1,3,6-h ep ta tr ien e
(77). To 11f (0.507 g, 1.23 mmol) and dimethyl fumarate (0.70
g) in acetonitrile (8 mL) was added TBAF (2.4 mL, 2.4 mmol,
1 M in acetonitrile) over 56 min. The mixture was worked up
routinely and concentrated. The dimethyl fumarate was
removed by crystallization from methanol, and the mother
liquor was chromatographed twice with silica gel using 1:19
ethyl acetate:petroleum ether as solvent to obtain 76 and 77
as an oil in an 85:15 ratio as judged by 1H NMR (125 mg,
55%): 1H NMR (CDCl3) of isomer 76 δ 2.32 (3H, s), 3.30 (2H,
d), 4.93-5.31 (4H, m), 5.70-6.06 (2H, m), 6.79 (1H, dt), 7.11-
7.22 (4H, m).
Elim in a tion of Tr im eth yl[o-[1-m eth yl-1-(p-tolylsu lfo-
n yl)-5-h exen yl]ben zyl]sila n e (11h ). P r ep a r a tion of 2-o-
Tolyl-1,6-h ep ta d ien e (80). To 11h (0.324 g, 0.781 mmol) in
acetonitrile (5 mL) was added TBAF (1.5 mL, 1.5 mmol, 1 M
in acetonitrile) in 20 min. The mixture was processed rou-
tinely and concentrated. Chromatography on silica gel using
petroleum ether yielded 80 as an oil (77 mg, 53%): IR (neat)
1639, 905, 764, 730 cm-1; 1H NMR (CDCl3) δ 1.55 (2H, quintet),
2.17 (2H, q), 2.32-2.43 (5H, s with superimposed q), 4.92 (1H,
br s), 4.96-5.08 (2H, m), 5.23 (1H, br s), 5.75-5.92 (1H, m),
7.10-7.22 (4H, m).
The third eluent contained 33c (39 mg, 10%): mp 110-113
°C; IR (neat) 1597, 1311, 1302, 1282 cm-1; 1H NMR (CDCl3) δ
0.85 (3H, t), 1.84 (3H, s), 2.05 (1H, sextet), 2.38 (3H, s), 2.44
(3H, s), 2.88 (1H, sextet), 7.00-7.28 (8H, m); 13C NMR (CDCl3)
δ 8.2, 21.5, 22.8, 24.0, 27.9, 72.2, 125.5, 128.4, 128.7, 130.3,
131.6, 132.5, 132.5, 133.5, 140.1, 144.1; MS(EI) m/e (relative
intensity) 147.10 (93), 131.05 (36), 105.08 (100), 91.05 (47).
Cycloaddition s of r-Bu tyl-r-m eth yl-o-qu in odim eth an es
(29e,f) to Dim eth yl F u m a r a te; Dim eth yl 1-Bu tyl-1,2,3,4-
tetr ah ydr o-1-m eth yl-2,3-n aph th alen edicar boxylates (66a
a n d 66b). Reaction of 11e (0.501 g, 1.24 mmol) and dimethyl
fumarate (0.36 g, 2.48 mmol) in acetonitrile (8 mL) with TBAF
(2.5 mL, 2.5 mmol, 1.0 M in acetonitrile) followed by workup
yielded an oily solid. Dimethyl fumarate was removed via
crystallization from methanol, and the mother liquor was
concentrated and chromatographed on silica gel using 1:19
ethyl acetate:ligroin. The first eluent contained styrene 67
as an oil (0.034 g, 16%): IR (neat) 905, 770, 730 cm-1; 1H NMR
(CDCl3) δ 0.90 (3H, t), 1.28-1.45 (4H, m), 2.29-2.37 (5H, s
and superimposed q), 4.86 (1H, br s), 5.18 (1H, br s), 7.07-
7.20 (4H, m); 13C NMR (CDCl3) δ 13.9 (q), 19.8 (q), 22.5 (t),
30.0 (t), 37.5 (t), 113.4 (t), 125.3 (d), 126.6 (d), 128.3 (d), 130.0
(d), 134.8 (s), 143.3 (s), 150.3 (s); MS(EI) m/e (relative intensity)
174.14 (6), 159.12 (15), 145.10 (23), 132.09 (100), 117.07 (63);
HRMS calcd for C13H18 174.1408, found 174.1401.
The next eluent contained diastereomers 66a and 66b (0.179
1
g, 45%) as a liquid: IR (neat) 1736 cm-1; H NMR (CDCl3) δ
0.7-1.0 (5H, m), 1.0-1.4 (5H, m), 1.4-1.7 (3H, m), 1.7-2.0
(1H, m), 2.7-3.5 (2H, m), 3.7-3.8 (6H, 4s), 7.0-7.4 (4H, m);
MS(EI) m/e (relative intensity) 318.18 (6), 263.99 (13), 258.16
(47), 229.09 (39), 201.09 (100); HRMS calcd for C19H26O4
318.1831, found 318.1835. Anal. Calcd for C19H26O4: C, 71.67;
H, 8.23. Found: C, 71.46; H, 8.19.
Dim eth yl 1-Allyl-1,2,3,4-tetr a h yd r o-1-m eth yl-2,3-n a p h -
th a len ed ica r boxyla tes (68a a n d 68b). To 11g (500 mg,
1.29 mmol) and dimethyl fumarate (0.37 g, 2.6 mmol) in
acetonitrile (8 mL) was added TBAF (2.6 mL, 2.6 mmol, 1 M
in acetonitrile) in 50 min. After workup, dimethyl fumarate
was removed by crystallization from methanol. The mother
liquor was concentrated and chromatographed on silica gel
using 1:19 ethyl acetate:ligroin. The first eluent contained a
mixture of styrene derivatives 69a and 69b (28 mg, 14%). The
next eluent contained diastereomers 68a and 68b as an oil
(170 mg, 44%): IR (neat) 1740 cm-1; 1H NMR (CDCl3) δ 1.23,
1.51 (3H, two s), 2.3-3.1 (4H, m), 3.1-3.5 (2H, m), 3.70-3.75
(6H, m), 4.8-5.6 (3H, m), 7.0-7.4 (4H, m); MS(EI) m/e (relative
intensity) 302.15 (1), 229.09 (61), 201.10 (100); HRMS calcd
for C18H22O4 302.1518, found 302.1514.
Ack n ow led gm en t. We thank the National Science
Foundation for support of this research.
Su p p or tin g In for m a tion Ava ila ble: NMR spectra (96
pages). This material is contained in libraries on microfiche,
immediately follows this article in the microfilm version of the
journal, and can be ordered from the ACS; see any current
masthead page for ordering information.
Dim eth yl 1,2,3,4-Tetr a h yd r o-1-m eth yl-1-(2-p r op yl)-2,3-
n a p h th a len ed ica r boxyla tes (70a a n d 70b). To 11i (0.500
g, 1.02 mmol) and dimethyl fumarate (0.59 g, 4.08 mmol) in
acetonitrile (10 mL) was added TBAF (2.0 mL, 2.0 mmol, 1 M
in acetonitrile) in 30 min. Following workup, dimethyl fuma-
J O970592C