Experimental and theoretical evidence for oxirane formation reaction of pentacoordinate 1,2λ6-oxathietanes with retention of configuration

Full text of DOI:10.1021/ja9629975

J. Am. Chem. Soc. 1996, 118, 12455-12456
12455
Scheme 1a
Experimental and Theoretical Evidence for Oxirane
Formation Reaction of Pentacoordinate
1,2λ6-Oxathietanes with Retention of Configuration
Takayuki Kawashima,* Fumihiko Ohno, Renji Okazaki,*
Hirotaka Ikeda,† and Satoshi Inagaki*,†
Department of Chemistry, Graduate School of Science
The UniVersity of Tokyo, 7-3-1 Hongo
Bunkyo-ku, Tokyo 113, Japan
Department of Chemistry, Faculty of Engineering
Gifu UniVersity, 1-1 Yanagido, Gifu 501-11, Japan
ReceiVed August 26, 1996
a (a) 1.2 equiv of LDA, THF, -78 °C, 15 min; (b) PhCOCF3 (5)
THF, -78 °C, 15 min; (c) aqueous NH4Cl; (d) FCC (SiO2); (e) 2 equiv
of n-Bu4NF, THF, 0 °C, 30 min; (f) 1.0 equiv of Br2, 2.0 equiv of
Et3N, CCl4, 0 °C; 25 °C, 7 h; (g) mCPBA, Na2HPO4, CH2Cl2, 0 °C f
25 °C, 12 h.
From our interest in diheteracyclobutanes 1 bearing highly
coordinate main group elements at the neighboring position,1,2
we have reported the synthesis and thermolysis of the penta-
coordinate 1,2λ6-oxathietane 2.3,4 Almost quantitative oxirane
formation from 2 has suggested a possibility that the oxathietane
is an intermediate of the Corey-Chaykovsky reaction of
oxosulfonium ylides with carbonyl compounds.3
interaction between the oxido anion and the sulfonium cation,
which seems a driving force of the formation of the oxathietane
ring, would resist the C-C bond rotation. In this case, an
alternative mechanism such as a concerted mechanism or a front
attack of the oxido anion without the C-C bond rotation can
be expected to be operative. In order to elucidate these
possibilities, we have decided to examine the stereochemistry
of the oxirane formation. In this paper we wish to report the
first example of the oxirane formation with retention of
configuration and the theoretical study of this process.
Two diastereomers of pentacoordinate 1,2λ6-oxathietanes 3a
and 3b with the Martin ligand8 were synthesized by the same
method as previously reported (Scheme 1).3 The separation of
diastereomers 6a and 6b was nicely performed by flash column
chromatography (FCC, SiO2). The stereochemistry of 8a and
8b was determined by differential NOE experiments as fol-
lows: NOE between a methine proton of carbon-3 and ortho-
protons of the phenyl group of carbon-4 was observed for
(3S,4R)- or (3R,4S)-8a and not for (3S,4S)- or (3R,4R)-8b. Since
the stereochemistry around a pentacoordinate sulfur and the
relationship between the SdO group and the phenyl group at
carbon-3 for 3 are considered to be the same as those reported
for 2 and, furthermore, the relative stereochemistry around
carbon-3 and carbon-4 is retained during the oxidation of 8, 3a
and 3b are concluded to have the structures as shown in Scheme
1.
It has been proposed that the Corey-Chaykovsky reaction5
involves the formation of an anti-betaine followed by a back
side attack of an oxido anion on the â-carbon.6 But, if the
oxathietane is a real intermediate of the Corey-Chaykovsky
reaction,7 S-O bond heterolysis followed by C-C bond rotation
is necessary for such an oxirane formation. Electrostatic
† Gifu University.
(1) Kawashima, T.; Okazaki, R. Synlett 1996, 600-608. For pentaco-
ordinate 1,2-oxaphosphetanes, see: Kawashima, T.; Kato, K.; Okazaki, R.
Angew. Chem., Int. Ed. Engl. 1993, 32, 869-870. Kawashima, T.; Takami,
H.; Okazaki, R. J. Am. Chem. Soc. 1994, 116, 4509-4510. For oxetanes
having pentacoordinate group 14 elements, see: Kawashima, T.; Iwama,
N.; Okazaki, R. Ibid. 1992, 114, 7598-7599. Kawashima, T.; Nishiwaki,
Y.; Okazaki, R. J. Organomet. Chem. 1995, 499, 143-146. Kawashima,
T.; Iwama, N.; Okazaki, R. J. Am. Chem. Soc. 1993, 115, 2507-2508. For
pentacoordinate 1,2-azaphosphetidines, see: Kawashima, T.; Soda, T.;
Okazaki, R. Angew. Chem., Int. Ed. Engl. 1996, 35, 1096-1098.
(2) For tetracoordinate 1,2-oxachalcogenetanes, see: (a) Kawashima, T.;
Ohno, F.; Okazaki, R. J. Am. Chem. Soc. 1993, 115, 10434-10435. (b)
Kawashima, T.; Ohno, F.; Okazaki, R. Angew. Chem., Int. Ed. Engl. 1994,
33, 2094-2095.
Thermolysis of 3a gave the corresponding oxirane 9a along
with 5, phenyl-migrated ketone 10, benzaldehyde (11), cyclic
sulfinate 12, a diastereomeric mixture of cyclic thioacetal
S-oxides 13, and cyclic thioacetal 14 (Scheme 2).9 In sharp
contrast to the thermolysis of 2,3 the yield of oxirane 9a was
(3) Ohno, F.; Kawashima, T.; Okazaki, R. J. Am. Chem. Soc. 1996, 118,
697-698.
(4) This compound can be classified to sulfurane oxides. For previous
examples, see: Martin, J. C.; Perozzi, E. F. J. Am. Chem. Soc. 1974, 96,
3155-3168. Perozzi, E. F.; Martin, J. C.; Paul, I. C. Ibid. 1974, 96, 6735-
6744. Adzima, L. J.; Martin, J. C. Ibid. 1977, 99, 1657-1659. Lau, P. H.
W.; Martin, J. C. Ibid. 1977, 99, 5490-5491. Rongione, J. C.; Martin, J.
C. Ibid. 1990, 112, 1637-1638.
(6) Johnson, C. R.; Schroeck, C. W. J. Am. Chem. Soc. 1971, 93, 5303-
5305. Durst, T.; Viau, R.; Van Den Elzen, R.; Nguyen, C. H. J. Chem.
Soc., Chem. Commun. 1971, 1334-1336. Townsend, J. M.; Sharpless, K.
B. Tetrahedron Lett. 1972, 3313-3316. Durst, T.; Johnson, C. R.; Schroeck,
C. W.; Shanklin, J. R. J. Am. Chem. Soc. 1973, 95, 7424-7431.
(7) In the formation reaction of spiropentanes by the reaction of sulfonium
cyclopropylides with carbonyl compounds, a mechanism involving an
oxathietane was proposed as an alternative one involving a ring expansion
to a σ-sulfurane having an oxirane ring followed by reductive elimination
of the sulfide, see: Bogdanowicz, M. J.; Trost, B. M. Tetrahedron Lett.
1970, 887-890. Trost, B. M.; Bogdanowicz, M. J. J. Am. Chem. Soc. 1973,
95, 5298-5307.
(5) For the Corey-Chaykovsky reactions, see: (a) Johnson, A. W.;
LaCount, R. B. J. Am. Chem. Soc. 1961, 83, 417-423. (b) Corey, E. J.;
Chaykovsky, M. Ibid. 1962, 84, 3782-3783. (c) Corey, E. J.; Chaykovsky,
M. Ibid. 1965, 87, 1353-1364. (d) Aube´, J. In ComprehensiVe Organic
Synthesis: SelectiVity, Strategy, and Efficiency in Modern Synthetic
Chemistry; Trost, B. M., Fleming, I., Eds.; Pergamon: Oxford, 1991; Vol.
1, pp 822-825. For the synthesis of optically active oxiranes via sulfur
ylides, see: (e) Furukawa, N.; Sugihara, Y.; Fujihara, H. J. Org. Chem.
1989, 54, 4222-4224. (f) Breau, L.; Ogilvie, W. W.; Durst, T. Tetrahedron
Lett. 1990, 31, 35-38. (g) Solladie´-Cavallo, A.; Adib, A. Tetrahedron 1992,
48, 2453-2464. (h) Aggarwal, V. K.; Abdel-Rahman, H.; Jones, R. V. H.;
Lee, H. Y.; Reid, B. D. J. Am. Chem. Soc. 1994, 116, 5973-5974. (i)
Aggarwal, V. K.; Thompson, A.; Jones, R. V. H.; Standen, M. Tetrahe-
dron: Asymmetry 1995, 6, 2557-2564. (j) Li, A.-H.; Dai, L.-X.; Hou, X.-
L.; Huang, Y.-Z.; Li, F.-W. J. Org. Chem. 1996, 61, 489-493. For the
related reactions of aminosulfoxonium ylides, see: (k) Johnson, C. R. Acc.
Chem. Res. 1973, 6, 341-347.
(8) For the bidentate ligand which is very effective in stabilizing the
higher coordination states of nonmetallic elements, see: Perozzi, E. F.;
Michalak, R. S.; Figuly, G. D.; Stevenson, W. H., III; Dess, D. B.; Ross,
M. R.; Martin, J. C. J. Org. Chem. 1981, 46, 1049-1053.
(9) Products 5, 10, 12, and 13 are thought to be formed via a mechanism
similar to that reported in ref 2b. Benzaldehyde (11) and 14 seem to be
formed as follows: the oxosulfonium ylide, which is formed by retroaddition
of 3 together with 5, reacts with 13 to give 14 and the corresponding inner
oxosulfonium oxide, which undergoes C-S bond cleavage to afford 11
and 12.
S0002-7863(96)02997-6 CCC: $12.00 © 1996 American Chemical Society

12456 J. Am. Chem. Soc., Vol. 118, No. 49, 1996
Communications to the Editor
Scheme 2
Scheme 4
The present unprecedented results prompted us to study
theoretically the oxirane formation from 1,2-oxathietanes.
Transition states for the concerted oxirane formation from simple
1,2-oxathietanes 15-18 as model compounds were located by
ab initio calculations (RHF/4-31G*).12 The activation energies
1
a Obtained by H and 19F NMR. b In CDCl3. c In THF-C6D6 (6:1).
d The ratio of two diastereomers was shown in the parentheses.
e Observed by GC-MS.
Scheme 3
for the process were calculated to be 28.2, 46.7, 45.3, and 53.8
kcal mol-1 for 15, 16, 17,13 and 18, respectively. The structure
of the transition state and energy diagram for the oxirane
formation from 18 are shown in Scheme 4. The values of
activation energy correspond to how much the substituents can
stabilize the positively polarized central sulfur atom; oxo and
hydroxyl groups destabilize the positive charge on the sulfur
atom more than hydrogen. A similar polarized transition state
was reported for the apical-equatorial ligand coupling of
sulfuranes.14 This is the first finding for oxirane formation
pathway from 1,2-oxathietanes, which can be recognized as a
carbon-oxygen ligand-coupling reaction of sulfuranes.15
In conclusion, we have demonstrated the first example for
the oxirane formation with retention of configuration, which
can be regarded as a salt-free Corey-Chaykovsky reaction. A
theoretical study revealed that the oxirane formation proceeds
via a concerted mechanism involving a polarized transition state.
quite low, but only a single isomer was obtained. Similarly,
the thermolysis of 3b afforded the other isomer 9b stereospe-
cifically.
Differential NOE experiments showed that 9a and 9b are (Z)-
and (E)-isomers, respectively, indicating that the oxirane forma-
tion proceeds with retention of configuration (Scheme 3). That
is, the stereochemistry of the oxirane formation was completely
reverse to that expected for the back side attack of the oxido
anion. Pentacoordinate 1,2λ6-oxathietanes 3 are formally
considered as [2 + 2]cycloadducts of oxosulfonium ylides with
carbonyl compounds. Furthermore, the 1,2-oxathietane forma-
tion was shown to be a no activation energy process by the
previous theoretical calculation.10 Our study on the isomeriza-
tion of tetracoordinate (E)- and (Z)-1,2λ4-oxathietanes via
retroaddition-recombination of sulfur ylides with benzophenone
also suggests the possibility that the 1,2-oxathietanes are
intermediates of the Corey-Chaykovsky reaction.2b These
results strongly suggest that 1,2-oxathietanes are intermediates
of the reaction of the sulfur ylides with carbonyl compounds
and decompose to give the oxirane with retention of configu-
ration. The Corey-Chaykovsky reaction has usually been
carried out in the presence of salts which were formed in the
preparation of sulfur ylides. So, we investigated the effect of
salts on the stereochemistry of oxirane formation. Both
thermolyses of 3a and 3b in the presence of 5 equiv of lithium
bromide in THF-C6D6 (6:1) gave a mixture of oxiranes 9a and
9b in the ratios of 17:7 and 2:16, respectively, in sharp contrast
to the results in the absence of the salts (Scheme 2), indicating
that lithium salts can assist the back side attack. This probably
explains why the stereochemistry of the typical Corey-
Chaykovsky reaction is completely different from that of the
present oxirane formation. Therefore, the present reaction can
be recognized as a salt-free Corey-Chaykovsky reaction.11
Acknowledgment. This work was partially supported by Kurata
Research Grant (T.K.) and Grant-in-Aid for General Scientific Research
(B) No. 07454160 (T.K.) from the Ministry of Education, Science and
Culture. F.O. thanks Research Fellowships of the Japan Society for
the Promotion of Science for Young Scientists. We thank Sin-etsu
Chemical, Central Glass, and Tosoh Akzo Co., Ltd., for gifts of silyl
chlorides, hexafluorocumyl alcohol, and alkyllithiums, respectively.
Supporting Information Available: An experimental procedure
for the synthesis of 3a and 3b and physical and spectral data for 3a,
3b, 6-8, 10, and 13 (8 pages). See any current masthead page for
ordering and Internet access instructions.
JA9629975
(11) The first example was reported in ref 5a, but the reaction was
considered to proceed via a betaine.
(12) Frisch, M. J.; Trucks, G. W.; Head-Gordon, M.; Gill, P. M. W.;
Wong, M. W.; Foresman, J. B.; Johnson, B. G.; Schlegel, H. B.; Robb, M.
A.; Replogle, E. S.; Gomperts, R.; Andres, J. L.; Raghavachari, K.; Binkley,
J. S.; Gonzalez, C.; Martin, R. L.; Fox, D. J.; DeFrees, D. J.; Baker, J.;
Stewart, J. J. P.; Pople, J. A. GAUSSIAN 92, Revision C; Gaussian, Inc.:
Pittsburgh, PA, 1992.
(13) Another transition state from the SdO apical pseudorotamer was
located for 17 (30.7 kcal mol-1).
(14) Moc, J.; Dorigo, A. E.; Morokuma, K. Chem. Phys. Lett. 1993, 204,
65-72 and references cited therein.
(15) The ligand-coupling reactions involving a sulfurane intermediate
have been reported. For a recent review, see: Oae, S.; Uchida, Y. Acc.
Chem. Res. 1991, 24, 202-208. For a recent example of the ligand coupling
reaction from sulfuranes which was spectroscopically identified, see:
Ogawa, S.; Sato, S.; Furukawa, N. Tetrahedron Lett. 1992, 33, 7925-7928.
(10) Volatron, F.; Eisenstein, O. J. Am. Chem. Soc. 1987, 109, 1-14.