1,3-Bis(phenylsulfonyl)allene as a new reagent for cycloaddition methodology

Article abstract of DOI:10.1055/s-1998-1802

1,3-Bis(phenylsulfonyl)allene 2 has been synthesised as a new reagent for cycloaddition methodology. In contrast to phenylsulfonylallene 1, thermal reaction of 2 with substituted 1,3-dienes gave both [2+2] as well as [2+4] cycloaddition products.

Full text of DOI:10.1055/s-1998-1802

900
LETTERS
SYNLETT
1,3-Bis(phenylsulfonyl)allene as a New Reagent for Cycloaddition Methodology
James R. Bull, Nicholas S. Desmond-Smith, Steven J. Heggie, Roger Hunter,* and Feng-Chang Tien
Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
E-mail: Roger@psipsy.uct.ac.za
Fax: 2721 689 7499
Received 25 April 1998
11
Abstract: 1,3-Bis(phenylsulfonyl)allene 2 has been synthesised as a
new reagent for cycloaddition methodology. In contrast to
cycloaddition results are presented in Scheme 2 (yields refer to
isolated products after column chromatography on SiO ).
2
phenylsulfonylallene 1, thermal reaction of 2 with substituted 1,3-dienes
gave both [2+2] as well as [2+4] cycloaddition products.
Allenes bearing electron withdrawing substituents have enjoyed
considerable attention in cycloaddition methodology in recent years
1
owing to the potential for synthetic manipulation of the cycloadducts.
2
While allenic esters have been developed in both racemic as well as
homochiral forms, sulfonyl-substituted allenes have not hitherto been
3
4,5
developed to a similar extent and, with a few exceptions,
have
generally appeared in the literature at the mono-substituted or 1,1-
disubstituted levels, in which axial enantiodifferentiation is not a
6
consideration. Thus, phenylsulfonylallene 1 has been demonstrated to
be
a reliable dienophile in [2+4] thermal processes, while
7
5
chloromethylsulfonylallene and trichloromethylsulfonylallene have
both been shown to be highly reactive, reacting with cyclopentadiene at
room
temperature.
In
this
letter,
we
introduce
1,3-
Scheme 2
bis(phenylsulfonyl)allene 2 to the cycloaddition repertoire and report on
preliminary investigations into both its reactivity and periselectivity in
cycloaddition processes.
The mixture of cycloadducts 9-12 underwent base-mediated
aromatisation to a common product 13, analogous to that reported for
the furan-phenylsulfonylallene cycloadduct,
hydride treatment was required to convert unreacted 9 from the t-
butoxide step into 13.
12
1,3-Bis(phenylsulfonyl)allene 2 was prepared in a straightforward
manner via a regioselective and stereoselective (trans) radical addition
of phenylsulfonyl iodide to 3-phenylsulfonylpropyne followed by
dehydroiodination using triethylamine in dichloromethane at low
temperature, Scheme 1. The addition step was initially carried out using
a sun lamp, but subsequent work established thermal conditions
(benzene/reflux) using AIBN as a radical initiator to be superior in
6a
Scheme 3. Sodium
8
terms of both time of reaction and conversion. In spite of its Michael
9
acceptor activity
-
MeOH treatment (reflux/24h) gave the
corresponding -(E) vinyl ether addition product in 82% yield - it proved
possible to isolate 2 in 95% yield from the reaction mixture via
conventional aqueous work-up and extraction. This isolate was shown
Scheme 3
1
by H NMR to be at least 95% pure and suitable for direct use in
Scheme 2 highlights two important differences between allenes 1 and 2
in their reactions with cyclopentadiene and furan. Firstly, reaction times
are much shorter for 2, eg 2 min at 25° C compared with 8 h at 80°C for
1 with cyclopentadiene. Secondly, 2 gives significantly higher yields,
particularly in the furan case at higher temperature, of exo-cycloadducts
compared to 1 which reacts in an endo-stereoselective manner. A third
feature is the formation of all four stereoisomers in the furan case which
10
cycloaddition experiments. Analytically pure material could be
obtained via crystallisation from carbon tetrachloride, while flash
column chromatography also afforded high quality material.
Preliminary results suggest that chlorinated hydrocarbons serve as
suitable media for cycloaddition reactions at elevated temperature,
whereas tetrahydrofuran is unsuitable.
contrasts remarkably with the analogous reaction of allene-1,3-
3a
dicarboxylates
which only affords the exo-(Z) and endo-(Z)
stereoisomers. One may speculate about the factors influencing the
stereoselectivity, and the picture becomes considerably more complex
when one varies the diene reactant, since the question of [2+2] vs [2+4]
13
14
periselectivity becomes an issue. Both Padwa and Kanematsu have
demonstrated that substituted phenylsulfonylallenes undergo
intramolecular [2+2] thermal cycloadditions for which there has been
Scheme 1
15
much debate about mechanism, with that involving a diradical
intermediate being favoured. However, by comparison, examples of
The [2+4] cycloaddition of 2 with both cyclopentadiene and furan was
thermal intermolecular [2+2] cycloadditions of sulfonylallenes are
16
carried out as a comparison with the equivalent reactions using
scarce.
We have now discovered that [2+2] cycloadditions of 2 in
4a,c,d
phenylsulfonylallene 1 as the dienophile reported previously.
The
competition with the [2+4] process are quite common for a range of

August 1998
SYNLETT
901
dienes. However, product distributions are complex, and a clear
structure-reactivity relationship is not evident at this stage. Two cases
illustrating this point are presented in Scheme 4 in which competing
[2+2] and [2+4] processes are observed for the reaction of 2 with 1-
methyl-4-trimethylsilyloxycyclohexa-1,3-diene and cyclohexa-1,3-
2
3
a) Kozikowski, A. P.; Floyd, W. C.; Kuniak, M. P. J. Chem. Soc.,
Chem. Commun. 1977, 582. b) Ishar, M. P. S.; Wali, A.; Ghandi,
R. P. J. Chem. Soc. Perkin Trans. 1 1990, 2185.
Ikeda, I.; Honda, K.; Osawa, E.; Shiro, M.; Aso, M.; Kanematsu,
K. J. Org. Chem. 1996, 61, 2031. b) Ikeda, I.; Gondo, A.; Shiro,
M.; Kanematsu, K. Heterocycles 1993, 36, 2669. c) Schlessinger,
R.; Bergstrom, C. P. J. Org. Chem. 1995, 60, 16.
17
diene respectively. Furthermore, both processes produce adducts in
which the double bond generated from the allene can be either exocyclic
or endocyclic, inviting some probing mechanistic questions, about the
sequence of events associated with formation of the [2+2] cycloadducts.
All of the products could be structurally assigned using 2D NMR
techniques, and an X-ray crystal structure determination confirmed the
structure of the [2+2] cycloadduct 14, Figure 1.
4
Barbarella, G.;Cinquini, M.; Colonna, S. J. Chem. Soc., Perkin
Trans. 1, 1980, 1646.
5
6
Braverman, S.; Lior, Z. Tetrahedron Lett. 1994, 35, 6725.
a) Guildford, A. J.; Turner, R. W. J. Chem. Soc., Chem. Commun.
1983, 466. b) Pavri, N. P.; Trudell, M. L. Tetrahedron Lett. 1997,
38, 7993. c) Veniard, L.; Benaïm, J.; Pourcelot, G. C. R. Seances
Acad. Sci., 1968, C, 1092. d) Hayakawa, K.; Nishiyama, H.;
Kanematsu, K. J. Org. Chem. 1985, 50, 512
7
8
Block, E.; Putman, F. J. Am. Chem. Soc. 1990, 112, 4072.
a) Whitmore, F. C.; Thurman, N. J. Am. Chem. Soc. 1923, 45,
1068. b) Truce, W. E.; Wolf, G. C. J. Org. Chem. 1971, 36, 1727.
c) Harwood, L. M.; Julia, M.; Le Thuillier G. Tetrahedron 1980,
36, 2483.
9
Phenylsulfonylallene has been shown to be an excellent Michael
acceptor: Padwa, A.; Austin, D. J.; Ishida, M.; Muller, C. L.;
Murphree, S. S.; Yeske, P.E. J. Org. Chem. 1992, 57, 1161.
10 All new compounds were fully characterised by elemental
analysis and spectroscopic data. Cpd. 2: m.p. 105-106°C (from
Scheme 4
CCl ); δ (200 MHz, CDCl ) 6.73 (2H, s, 1- and 3-H), 7.55-7.76
4
H
3
(6H, m, m- and p-H of SO C H ), and 7.93-8.01 (4H, m, o-H of
2
6 5
SO C H ); δ (50MHz, CDCl ) 108.0 (2C, d, C-1 and C-3),
2
6
5
C
3
128.1 and 129.5 (each 4C, d, o- and m-C of SO C H ), 134.5 (2C,
2
6 5
d, p-C of SO C H ), 139.9 (2C, s, C-1 of SO C H ).
2
6
5
2 6 5
11 Selected NMR data (400 MHz, CDCl ) for cpds. 5, 6, 9, 10, 11
3
and 12: δ 4.69 (1H, dd, J 2.9 and 2.8 Hz, 5-H ), 6.2 (1H, dd, J
H
n
5.5 and 3.0 Hz, 3-H), 6.25 (1H, ddd, J 5.5, 3.2 and 0.8 Hz, 2-H),
6.52 (1H, d, 2.9 Hz, 1´-H); 6: δ 5.28 (1H, dd, J 3.7 and 2.3 Hz, 5-
H
H ), 6.18 (1H, dd, J 5.6 and 3.2 Hz, 2-H), 6.51 (1H, dd, J 2.3 and
x
0.8 Hz, 1´-H), 6.72 (1H, dd, J 5.6 and 2.8 Hz, 3-H); 9: δ 3.72
H
(1H, dd, J 1.5 and 0.8 Hz, 5-H ), 6.50 (1H, dd, J 5.6 and 1.8 Hz, 2-
n
H), 6.61 (1H, dd, J 5.6 and 2.0 Hz, 3-H), 6.79 (1H, dd, J 1.5 and
1.4 Hz, 1´-H); 10: δ 4.83 (1H, dd, J 1.9 and 0.8 Hz, 5-H ), 6.43
H
n
(1H, dd, J 5.6 and 1.9 Hz, 3-H), 6.53 (1H, dd, J 5.6 and 1.9 Hz, 2-
H), 6.57 (1H, dt, J 1.9 and 2x0.8 Hz, 1´-H); 11: δ 5.35 (1H, dd, J
H
4.5 and 2.1 Hz, 5-H ), 6.47 (1H, d, J 2.1 Hz, 1´-H), 6.58 (1H, dd, J
x
5.6 and 1.9 Hz, 3-H), 7.07 (1H, ddd, J 5.6, 1.6 and 0.7 Hz, 2-H);
12: δ 4.31 (1H, dd, J 3.9 and 1.9 Hz, 5-H ), 6.39 (2H, m, 1- and
H
x
3-H), 6.46 (1H, dd, J 5.8 and 1.9 Hz, 2-H), 6.76 (1H, dd, J 1.9 and
1.2 Hz, 1´-H).
12 Selected data for cpd. 13: m.p. 165-167°C (from EtOAc-hexane);
δ
5.19 (2H, s, 1´-H ), 7.24-7.40 (2H, m, 6- and 5-H), 7.40-7.76
2
H
In conclusion, allene 2 extends the repertoire for sulfonylallenes in
cycloaddition methodology. Further studies are in progress to delineate
its profile in synthesis.
(7H, m, 4-H and m- and p-H of SO C H ), 7.79-7.94 (4H, m, o-H
of SO C H ).
2
6 5
2
6 5
13 a) Padwa, A.; Lipka, H.; Watterson, S. H.; Tetrahedron Lett. 1995,
36, 4521. b) Padwa, A.; Meske, M.; Murphree, S. S.; Watterson,
S. H.; Ni, Z. J. Am. Chem. Soc. 1995, 117, 7071. c) Padwa, A.;
Filipkowski, M. A.; Meske, M.; Watterson, S. H.; Ni, Z. J. Am.
Chem. Soc. 1993, 115, 3776.
Acknowledgements. We thank the Foundation for Research and
Development Pretoria, AECI Ltd and the University of Cape Town for
financial support.
14 Yeo, S. K.; Shiro, M.; Kanematsu, K. J. Org. Chem. 1994, 59,
References and Notes
1621.
1
See the allene section in: Kappe, C. O.; Murphree, S. S.; Padwa,
A. Tetrahedron 1997, 53, 14179.
15 a) Pasto, D. J.; Sugi, K. D.; Alonso, D. E.; J. Org. Chem. 1992, 57,
1146. b) Dolbier, W. R. Acc. Chem. Res. 1991, 24, 63.

902
LETTERS
SYNLETT
16 Snider. B. B.; Spindell, D. K. J. Org. Chem. 1980, 45, 5017.
17 Selected NMR data (400MHz, CDCl ) for cpds. 14-18: 14, δ
H), 4.61 and 5.03 (each 1H, d, J 13.2 Hz, 1´-H), 6.12 (1H, ddd, J
7.3, 6.2 and 1.5 Hz, 6-H), 6.39 (1H, ddd, J 7.3, 5.9 and 1.4 Hz, 5-
3
H
H); 18, δ 2.56 (1H, dtd, J 6.4, 2x2.8 and 1.5 Hz, 1-H), 2.84 (1H,
1.74 (3H, br s, 3-Me), 3.37 (1H, br d, J 5.5 Hz, 1-H), 3.86 (1H,
dd, J 14.2 and 1.0 Hz, 1´-H), 4.95 (1H, dd, J 14.2 and 0.8 Hz, 1´-
H
m, W 17 Hz, 4-H), 5.33 (1H, dd, J 2.7 and 2.1 Hz, 5-H ), 5.89
x
(1H, ddd, J 7.9, 6.4 and 1.5 Hz, 2-H), 6.10 (1H, d, J 2.7 Hz, 1´-H),
6.4 (1H, ddd, J 7.9, 6.3 and 1.5 Hz, 3-H).
H), 5.46 (1H, dq, J 5.5 and 3x1.6 Hz, 2-H); 15, δ 0.73 (3H, s, 1-
H
Me), 5.22 (1H, d, J 8.0 Hz, 3-H), 5.85 (1H, t, J 2x2.0 Hz, 5-H ),
n
6.06 (1H, dd, J 8.0 and 1.0 Hz, 2-H), 6.27 (1H, d, J 2.0 Hz, 1´-H);
16, δ 3.21 (1H, m, W 28 Hz, 1-H), 3.64 (1H, m, W 28 Hz, 6-H),
H
4.18 (1H, ddd, J 6.5, 3.4 and 2.3 Hz, 8-H), 5.44 (1H, ddt, J 9.8, 3.8
and 2x1.9 Hz, 2-H), 5.95 (1H, dddd, J 9.8, 4.6, 4.3 and 1.4 Hz, 3-
H), 6.42 (1H, t, J 2x2.3 Hz, 1´-H); 17, δ 3.69 (1H, dtd, J 6.2,
H
2x2.5 and 1.5 Hz, 1-H), 4.11 (1H, dtd, J 5.9, 2x2.5 and 1.5 Hz, 4-