Shigeo Sugiyama

A novel dynamic kinetic resolution accompanied by intramolecular transesterification: asymmetric synthesis of a 4-hydroxymethyl-2-oxazolidinone from serinol derivatives

Reaction paths of the one-pot reaction of (R)-2-(α-methylbenzyl)amino-1,3-propanediol (1) and 2-chloroethyl chloroformate with DBU giving (4S,αR)-4-hydroxymethyl-3-(α-methylbenzyl)-2-oxazolidinone [(4S)-2] (94% de) were investigated. Intermediates of this reaction, 2-chloroethyl (2S)- and 2-chloroethyl (2R)-3-hydroxy-2-[(αR)-α-methylbenzyl]aminopropyl carbonates [(2S)-4 and (2R)-4], were synthesized individually. After the addition of DBU to the respective solution of the carbonate (2S)-4 and that of (2R)-4 in dichloromethane, the intramolecular transesterification between (2S)-4 and (2R)-4 and the diastereoselective intramolecular cyclization proceeded to afford (4S)-2 in high diastereomeric excess. Therefore, two monocarbonates (2S)-4 and (2R)-4 were kinetically resolved by this cyclization during the intramolecular transesterification between (2S)-4 and (2R)-4. We found that this process involved dynamic kinetic resolution accompanied by intramolecular transesterification.

ASYMMETRIC SYNTHESIS OF THE 4-HYDROXYMETHYL-2-OXAZOLIDINONE FROM THE SERINOL DERIVATIVE AND CHLOROFORMATES

Asymmetric desymmetrization of 2-[(αR)-α-methylbenzyl]amino-1,3-propanediol (1) with 2-chloroethyl chloroformate and DBU at room temperature gave optically active (4S)-4-hydroxymethyl-N-[(αR)-α-methylbenzyl]-2-oxazolidinone [(4S)-2] (up to 94% de). This reaction involves kinetic resolution and [1,3]-alkoxyacyl migration of 2-chloroethyl (2S)- and 2-chloroethyl (2R)-3-hydroxy-2-[(αR)-α-methylbenzyl]aminopropyl carbonates [(2S)-4 and (2R)-4].

Chemoselective Debezylation of the N-1-Phenylethyl Group in 2-Oxazolidinones by the Anisole-Methanesulfonic Acid System

The chemoselective removal of N-1-phenylethyl group in 2-oxazolidinones by the anisole-methanesulfonic acid system was investigated. Optically active 4,5-cis- and 4,5-trans-diphenyl-2-oxazolidinones (1a-d) were easily synthesized from dl-stilbene oxides (trans- and cis-7a) using this debenzylation.

One-pot acylation and fractional crystallization: preparation of optically active serinol monobenzoates

Abstract Mono-O-acylation of (R)-2-(α-methylbenzyl)amino-1,3-propanediol 1 with 4-nitrobenzoyl chloride and DMAP in dichloromethane at room temperature gave crystals of optically active (2S,αR)-3-hydroxy-2-(α-methylbenzyl)aminopropyl 4-nitrobenzoate hydrochloride [(2S)-2a·HCl] in 33% yield by fractional crystallization. Optically active oxazolidinones, aziridines, and serinol derivatives were synthesized from the benzoate (2S)-2a.

Stereoselective Gram-Scale Synthesis of (S)-5,5-Dimethyl-4-phenyloxazolidin-2-one

A stereoselective gram-scale synthesis of (S)-5,5-dimethyl-4-phenyl-oxazolidin-2-one, SuperQuat [(S)-1], is described. The key step is the diastereoselective reduction of (E)-imine (2), which is synthesized from 2-hydroxy-2-methylpropiophenone (4) and (S)-α-methylbenzylamine using sodium borohydride and acetic acid to give (1S,αS)-2-methyl-1-(a-methyl-benzyl)amino-1-phenylpropan-2-ol (5).

Photoreactions of β-aziridinylacrylonitrile. 1,3-Dipolar cycloadditions of photoinduced azomethine ylide

The photoinduced azomethine ylide A from the 3-(1-benzylaziridin-2-yl)prop-2-enenitrile 1 undergoes 1,3-dipolar cycloaddition with electron-deficient olefins to give the head-to-head adducts selectively and efficiently.

A metal-free biaryl coupling reaction activated by a sulfonium salt

An intermolecular biaryl coupling reaction of phenol derivatives activated by a sulfonium salt formed from diphenyl sulfoxide and trifluoromethanesulfonic anhydride has been developed. The method is a rapid, one-pot reaction leaving no trace of the sulfonium moiety in the coupling products. Tri-substituted phenyl ethers also gave coupling products in moderate yields.

Novel photoadditions of tertiary amines to the α-position of α,β-unsaturated γ,δ-epoxy nitriles

The photoreactions of α,β-unsaturated γ,δ-epoxy nitriles 1, 2, 13 and 16 with triethylamine give rise to novel 1 ∶ 1 α-adducts (e.g., 5) efficiently. After treatment with silica gel, the adducts undergo retro-Michael reaction leading to the corresponding α-alkylidenenitrile derivatives (e.g., 3). The epoxy nitrile 1 also reacts with various tertiary amines to afford α-adducts. The reaction of 1 and the silylamine 24 gives mainly methylene derivative 22 and silylated compound 25 after treatment with silica gel. The reaction may proceed via single- electron-transfer from the amine to the excited epoxy nitrile.