An efficient and catalytically enantioselective route to (S)-(-)-phenyloxirane

Corey, E. J.; Shibata, Saizo; Bakshi, Raman K.

doi:10.1021/jo00247a044

Cited by 405 publications

(134 citation statements)

References 6 publications

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“…Work is underway to improve yields of the reaction sequence 74 → 73 → 75 → 76, to desymmetrize 76 and to convert it into long-chain polyketides of natural products of biological interest. In preliminary studies we have found that the double adduct of PhSH to 76 can be reduced stereoselectively with catecholborane and the CBS catalyst B-Me-(S)-CBS [168][169][170][171] giving 77 in 58 % yield. Using a 1:1 mixture of 74 and ent-70b, a 55 % yield of 78 is obtained.…”

Section: Methodsmentioning

confidence: 99%

Use of sultines in the asymmetric synthesis of polypropionate antibiotics

Vogel

Turks

Bouchez

et al. 2008

Pure and Applied Chemistry

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At low temperature and in the presence of an acid catalyst, SO 2 adds to 1,3-dienes equilibrating with the corresponding 3,6-dihydro-1,2-oxathiin-2-oxides (sultines). These compounds are unstable above -60°C and equilibrate with the more stable 2,5-dihydrothiophene 1,1-dioxides (sulfolenes). The hetero-Diels-Alder additions of SO 2 are suprafacial and follow the Alder endo rule. The sultines derived from 1-oxy-substituted and 1,3-dioxydisubstituted 1,3-dienes cannot be observed at -100°C but are believed to be formed faster than the corresponding sulfolenes. In the presence of acid catalysts, the 6-oxy-substituted sultines equilibrate with zwitterionic species that react with electron-rich alkenes such as enoxysilanes and allylsilanes, generating β,γ-unsaturated silyl sulfinates that can be desilylated and desulfinylated to generate polypropionate fragments containing up to three contiguous stereogenic centers and an (E)-alkene unit. Alternatively, the silyl sulfinates can be reacted with electrophiles to generate polyfunctional sulfones (one-pot, four-component synthesis of sulfones), or oxidized into sulfonyl chlorides and reacted with amines, then realizing a one-pot, four-component synthesis of polyfunctional sulfonamides. Using enantiomerically enriched dienes such as 1-[(R)-or 1-(S)-phenylethyloxy]-2-methyl-(E,E)-penta-1,3-dien-3-yl isobutyrate, derived from inexpensive (R)-or (S)-1-phenylethanol, enantiomerically enriched stereotriads are obtained in one-pot operations. The latter are ready for further chain elongation. This has permitted the development of expeditious total asymmetric syntheses of important natural products of biological interest such as the baconipyrones, rifamycin S, and apoptolidin A.

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Section: Methodsmentioning

confidence: 99%

Use of sultines in the asymmetric synthesis of polypropionate antibiotics

Vogel

Turks

Bouchez

et al. 2008

Pure and Applied Chemistry

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“…[1][2][3][4][5][6] Especially, the use of the oxazaborolidine, MeCBS or HCBS, prepared from chiral a,a-diphenyl-2-pyrrolidinemethanol (DPP) for the asymmetric borane reduction of various ketones showed high enantioselectivities ( Fig. 1).…”

mentioning

confidence: 99%

Asymmetric Borane Reduction of Prochiral Ketone Using Chiral Bis(.ALPHA.,.ALPHA.-diphenyl-2-pyrrolidinemethanol) Carbonate.

Yanagi

Kikuchi

Takeuchi

et al. 2003

CHEMICAL & PHARMACEUTICAL BULLETIN

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Several asymmetric borane reductions of prochiral ketones using a chiral oxazaborolidine catalyst prepared from a chiral b-amino alcohol have been reported. [1][2][3][4][5][6] Especially, the use of the oxazaborolidine, MeCBS or HCBS, prepared from chiral a,a-diphenyl-2-pyrrolidinemethanol (DPP) for the asymmetric borane reduction of various ketones showed high enantioselectivities ( Fig. 1). HCBS could be synthesized from DPP and a reducing reagent such as the borane-dimethyl sulfide complex (BH 3 · Me 2 S) or the borane-tetrahydrofuran complex. However, the synthesis of HCBS requires a long reaction time in tetrahydrofuran (THF).3) Masui and Shioiri reported the asymmetric reduction by BH 3 · Me 2 S using a catalyst easily generated in situ from chiral DPP and trimethyl borate. 7) We have also reported the efficient catalyst prepared from aluminum triethoxide 8) and DPP for asymmetric borane reduction. However, the additive, trimethyl borate or aluminum triethoxide, is necessary to prepare the catalysts in these methods. Mathre et al. tried to prepare a borane complex of HCBS in toluene by the same procedure used to prepare a borane complex of MeCBS (Fig. 1), but they obtained only a dimer complex.5) Salunkhe and Burkhardt reported that the complex generated from the chiral DPP and borane in toluene included the dimer complex.6) Efforts to use the dimer complex as a catalyst resulted in a low enantioselectivity for the reduction of acetophenone.In this paper, we report the asymmetric borane reduction of a prochiral ketone using a catalyst generated in situ from DPP and BH 3 · Me 2 S in various solvents. We also report that the carbonate of DPP is useful for the reduction.In our previous report, 8) we described that the asymmetric reduction of acetophenone using (S)-DPP and BH 3 · Me 2 S in THF required a long reaction time (1.5 h) after the addition of the ketone and gave (1R)-1-phenylethanol with 94.7% ee. During the reaction, immediately after BH 3 · Me 2 S was added to a solution of (S)-DPP in THF, the addition of the ketone to the solution was started. We thought that if the mixture of (S)-DPP and BH 3 · Me 2 S was stirred to prepare a catalyst for a sufficient time before the addition of the ketone, the reaction time would be shorter and the optical purity of the alcohol would be higher.First we examined the asymmetric borane reduction of acetophenone using a catalyst generated in situ from DPP and BH 3 · Me 2 S in various solvents. A catalyst solution was generated from (S)-DPP (0.5 mmol) and BH 3 · Me 2 S (5 mmol) in each solvent (5 ml) by stirring at room temperature for 1 h. A solution of acetophenone (5 mmol) in each solvent (10 ml) was then added dropwise to the catalyst solution via a syringe pump at room temperature over 1 h. The reaction solution was stirred until the acetophenone disappeared based on TLC. The resulting solution was quenched with 1 mol/l HCl. The usual workup provided (1R)-1-phenylethanol. These results are shown in Table 1. The reaction in THF, ether, or hexane gave (1R)-1-pheny...

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“…CBS reduction is one of the most useful catalytic enantioselective reduction reactions 8) , in which optically active oxazaborolidine derived from a naturally occurring proline acts as a chiral catalyst. A multi-mode microwave reactor (Wave Magic MWO-1000S, EYELA) was used with an attached cooling unit to maintain the low temperature of the reaction mixture during microwave irradiation.…”

Section: Enantioselective Ring-opening Reaction Of Biaryl Lactones VImentioning

confidence: 99%

Microwave-specific Effect on Enantioselective Reactions

Sawada

Yamada

2018

J. Jpn. Petrol. Inst.

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Microwave irradiation is widely applied to organic synthesis. Many advantages of microwave irradiation, including drastic shortening of reaction time, suppression of side reactions, and/or higher chemical yield, have been proposed. Generally, these effects have been understood merely as a simple thermal effect, since microwave irradiation rapidly raises the temperature of the reaction mixture. However, some observed results could not be understood only by the thermal effect. Recently our group reported that several enantioselective reactions were accelerated under microwave irradiation without loss of enantioselectivity. As these extraordinary results could not be explained by the simple thermal effect, the concept of the "microwave-specific effect" should be considered. We describe our recent experimental results to elucidate the microwave-specific effect. Investigations are described on enantioselective ring-opening reactions of biaryl lactone derivatives, racemization of an optically pure biaryl lactone derivative, enantioselective Claisen rearrangement reaction, enantioselective Conia-ene reaction and ring-closing metathesis reaction. These reactions or racemization of optically pure compounds were accelerated under microwave conditions. Such reaction acceleration of enantioselective reactions was observed without loss of enantioselectivity.

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An efficient and catalytically enantioselective route to (S)-(-)-phenyloxirane

Cited by 405 publications

References 6 publications

Use of sultines in the asymmetric synthesis of polypropionate antibiotics

Use of sultines in the asymmetric synthesis of polypropionate antibiotics

Asymmetric Borane Reduction of Prochiral Ketone Using Chiral Bis(.ALPHA.,.ALPHA.-diphenyl-2-pyrrolidinemethanol) Carbonate.

Microwave-specific Effect on Enantioselective Reactions

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