Rhodium carbenoid mediated cyclisation of α-diazo-β-keto-δ-hydroxy- phenylsulfones

Article abstract of DOI:10.1016/S0040-4039(00)00724-3

The title reaction gave rise to 2-phenylsulfonyl-3-oxo-tetrahydrofurans in satisfactory yields providing an entry to some furan derivatives. (C) 2000 Published by Elsevier Science Ltd.

Full text of DOI:10.1016/S0040-4039(00)00724-3

Tetrahedron Letters 41 (2000) 4773±4776
Rhodium carbenoid mediated cyclisation of a-diazo-b-keto-d-
hydroxy-phenylsulfones
Fabienne Lacrampe, Francoise Leost and Alain Doutheau*
Â
Laboratoire de Chimie Organique, Institut National des Sciences Appliquees, 20 avenue A. Einstein, 69621 Villeurbanne,
France
Received 1 February 2000; accepted 2 May 2000
Abstract
The title reaction gave rise to 2-phenylsulfonyl-3-oxo-tetrahydrofurans in satisfactory yields providing
an entry to some furan derivatives. # 2000 Published by Elsevier Science Ltd.
Keywords: carbenoids; diazo compounds; furans; insertion reactions; sulfones.
Some years ago, Moody and co-workers prepared a 2-phenylsulfonyloxepan-3-one from the
Rh(II)-catalyzed cyclisation of a sulfonyl diazo precursor.1 To our knowledge this is the only
reported example of a carbenoid mediated intramolecular insertion reaction of a hydroxy
diazoketosulfone.2,3 As part of our continuing interest in the chemistry of diazo compounds,4 and
considering the importance of ®ve-membered oxygen heterocycles, we recently decided to
examine if the same methodology could be applied to the preparation of furanic derivatives. We
report in this note our preliminary results.
The required hydroxy-ketosulfones 2 were prepared by condensation of the dilithium salt of
phenylsulfonylacetone and carbonyl compounds 1 (Scheme 1).5 Compounds 2a±d were then
converted into the corresponding diazo compounds 3 by diazo transfer reaction using tosyl
azide.6
When a methylene chloride solution of compounds 3 was stirred at room temperature in the
presence of a catalytic amount of Rh2(OAc)4 the expected cyclisation reaction occurred to give
the tetrahydrofurans 4 in fairly good yields after silica gel chomatography.7,8 Except for gem-
dimethyl derivative 4d, in each case the ketofurans 4 were obtained as a mixture of diastereomers.
To obtain more elaborated compounds we then turned to an alternative route for the
preparation of b-keto-d-hydroxy-sulfones using the Claisen condensation between the dilithio-
anion of methylphenylsulfone and b-hydroxy esters.9 These conditions were ®rst applied to the
optically active ester 5a, prepared in 43% yield by the baker's yeast asymmetric reduction of
* Corresponding author. Fax: 33 04 72 43 88 96; e-mail: doutheau@insa-lyon.fr
0040-4039/00/$ - see front matter # 2000 Published by Elsevier Science Ltd.
PII: S0040-4039(00)00724-3

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Scheme 1. (a) CH3COCH2SO2Ph, 2 equiv. LDA, THF. (b) TsN3, K2CO3, MeCN. (c) Rh2OAc4 cat., CH2Cl2
methyl 2-oxocyclopentanecarboxylate according to the Kometani et al. procedure10 using glucose
as an energy source (Scheme 2). We thus obtained a mixture of expected ketosulfone 6a and of its
C-1 epimer in 64% yield. Careful column chromatography of this mixture allowed us to isolate
pure 6a in 40% yield. Under the same conditions, 5b, prepared in 83% yield by alkylation of 5a,11
led to 6b (71%). Compounds 6 were then transformed as previously into the corresponding diazo
compounds 7 which were submitted to cyclisation conditions12 to give 8a and 8b in satisfactory
yields.
Scheme 2.
We then explored some synthetic potentialities of the 3-oxo-tetrahydrofurans 4 (Scheme 3).13
Reductive desulfonylation14 of 4c in free radical conditions (Bu3SnH, AIBN)15 gave known
5-phenyl-3-oxo-tetrahydrofuran 916 in 80% yield. Sodium borohydride reduction of 4c led to the
alcohol 10 (73%) as a mixture (80:20) of two diastereomers.17 When the mesylate 11 prepared
from 10 was submitted to the action of potassium tert-butoxide it gave 5-phenyl-2-phenylsulfonyl-
3,4-dihydrofuran 14 in 88% yield. We then examined the possibility to convert 10 into the
dihydrofuran 15. For this purpose 10 was ®rst converted into the acetate 12 which was submitted
to the SmI2 mediated18 reductive elimination conditions of b-acetoxysulfones to give 15 in 46%
yield. This compound was obtained in a slightly higher yield (52%) by submitting the thioester
13, obtained quantitatively from 10, to radical generating conditions.19,20

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Scheme 3. (a) Bu3SnH, AIBN cat., PhCH3, Á. (b) NaBH4, EtOH. (c) t-BuOK/THF. (d) SmI2/HMPA, THF
In conclusion we report in this note that the Rh2(OAc)4 catalysed intramolecular insertion
reaction of a-diazo-b-keto-d-hydroxy-phenylsulfones proceeds in satisfactory yields providing an
entry to some furan derivatives. Since starting materials can be prepared in two steps from easily
obtained non racemic b-hydroxy esters the methodology should allow optically active compounds
to be readily prepared.
References
1. Davies, M. J.; Moody, C. J.; Taylor, R. J. J. Chem. Soc., Perkin Trans. 1 1991, 1±7. For the cyclisation of
g-hydroxy a-diazo-b-sulfonylesters into 3-oxocephan dioxides, see: Crackett, P. H.; Sayer, P.; Stoodley, R. J.;
Greengrass, C. W. J. Chem. Soc., Perkin Trans. 1 1991, 1235±1243.
2. For the copper catalysed intermolecular insertion reaction of a-diazo-b-ketosulfones into the O±H bond of
alcohols, see: Gunter, F.; Werner, J.; Schank, K. Liebigs Ann. Chem. 1976, 1713±1726.
3. For the preparation of cyclopentane derivatives by rhodium(II) catalyzed C±H insertion reaction of a-diazo-b-
ketosulfones, see: (a) Monteiro, H. J. Tetrahedron Lett. 1987, 28, 3459±3462. (b) Barre, V.; Uguen, D. Tetrahedron
Lett. 1987, 28, 6045±6048. (c) Babu, S. D.; Hrytsak, M. D.; Durst, T. Can. J. Chem. 1989, 67, 1071±1076.
4. (a) Collomb, D.; Deshayes, C.; Doutheau, A. Tetrahedron 1996, 52, 6665±6684. (b) Collomb, D.; Chantegrel, B.;
Deshayes, C. Tetrahedron 1996, 52, 10455±10472. (c) Collomb, D.; Doutheau, A. Tetrahedron Lett. 1997, 38,
1397±1398. (d) Leost, F.; Chantegrel, B.; Deshayes, C. Tetrahedron 1997, 53, 7557±7576; 1998, 54, 6457±6474. (e)
Leost, F.; Doutheau, A. Tetrahedron Lett. 1999, 40, 847±848.
5. Wada, E.; Pei, W.; Yasuoka, H.; Chin, U.; Kanemasa, S. Tetrahedron 1996, 52, 1205±1220.
6. All new compounds gave spectral and analytical data in full agreement with proposed structures.
7. To test the feasibility of the insertion reaction we selected the more commonly used rhodium(II) acetate as the
catalyst. We did not yet try to improve the yield by using other rhodium(II) derivatives or reaction conditions.
8. Typical procedure: to a solution of 3c (2.0 g, 6 mmole) in CH2Cl2 (50 mL; freshly distilled from P2O5) was added,
under N2 atmosphere, rhodium(II) acetate (15 mg, 0.5 mol%). The reaction mixture was stirred at room
temperature for 4 h until disappearance (TLC; pentane:AcOEt, 70:30) of starting material. After evaporation of
the solvent the crude product was chromatographed on silica gel (CH2Cl2) to give 4c (1.30 g, 70%) as a solid
(mixture of diastereomers). IR (CCl4): 1770 cm^1. 1H NMR (CDCl3): major isomer ꢀ 7.99±7.31 (m, 10H); 5.93 (dd,
1H, J=7.0, J=9.2); 5.08 (s, 1H); 3.18 (dd, 1H, J=7.0, J=18.7); 2.64 (dd, 1H, J=9.2, J=18.7). Minor isomer ꢀ
7.99±7.31 (m, 10H); 5.30 (dd, 1H, J=6.4, J=10.9); 4.95 (s, 1H); 2.97 (dd, 1H, J=6.4, J=17.7); 2.79 (dd, 1H,
J=10.9, J=17.7). 13C NMR: major isomer ꢀ 203.1; 139.0; 136.7; 134.8; 129.5; 128.9; 126.1; 93.0; 80.7; 44.2. Minor
isomer d 202.3; 138.8; 136.5; 134.8; 129.8; 129.5; 129.3; 129.1; 126.8; 92.4; 80.1; 44.7. Anal. calcd for C16H14O4S:
C, 63.56; H, 4.67. Found: C, 64.10; H, 4.70.
9. Choudhry, S. C.; Serico, L.; Cupano, J. J. Org. Chem. 1989, 54, 3755±3757.
10. Kometani, T.; Kitatsuji, E.; Matsuno, R. Chem. Lett. 1989, 1465±1466.
11. Nishimura, Y.; Mori, K. Eur. J. Org. Chem. 1998, 233±236.

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12. In the case of 7b the reaction mixture was re¯uxed for 1 h.
13. To the best of our knowledge 3-oxo-tetrahydrofurans bearing a sulfonyl group in C-2 position have not yet been
described in the literature.
14. For a recent review on desulfonylation, see: Najera, C.; Yus, M. Tetrahedron 1999, 55, 10547±10658.
15. Smith, A. B.; Hale, K. J.; McCauley, J. P. Tetrahedron Lett. 1989, 30, 5579±5582.
16. Calter, M. A.; Sugathapala, P. M.; Zhu, C. Tetrahedron Lett. 1997, 38, 3837±3840.
17. The reduction of the mixture of the two diastereomers of 4c led to only two diastereomers of 10, among four
possible. This result is in accordance with the well documented high cis diastereoselectivity of sodium borohydride
reduction of b-ketosulfones. Since it was quite unlikely that the success of the chemistry planned to transform 10
into dihydrofuran derivatives, would signi®cantly depend on the cis or trans relationship between the hydroxy-
phenylsulfonyl moiety and the phenyl group, at this stage of our work we did not try to assign the stereochemistry
of the major and of the minor diastereomer. We further used the former compound obtained in larger amount.
18. (a) de Pouilly, P.; Vauzeilles, B.; Mallet, J.-M.; Sinay, P. C. R. Acad. Sci., Paris 1991, 313, 1391±1394. (b) de
Pouilly, P.; Chenede, A.; Mallet, J.-M.; Sinay, P. Bull. Soc. Chim. Fr. 1993, 130, 256±265. For the SmI2 promoted
reductive elimination of b-hydroxy imidazolyl sulfones, see: Kende, A. S.; Mendoza, J. S. Tetrahedron Lett. 1990,
31, 7105±7108.
19. Lythgoe, B.; Waterhouse, I. Tetrahedron Lett. 1977, 48, 4223±4226.
20. Similar yields have been reported in the literature for sodium amalgam desulfonation of b-hydroxy sulfones
leading to cyclopentene derivatives. For example, see: Gamble, M. P.; Gibbin, G. M. P.; Taylor, R. J. K. Synlett
1995, 779±780.