Hirotoshi Kawabata

Lewis base-catalyzed transformation of α, β-unsaturated aldehydes to saturated carboxylic acids, esters and amides

Abstract The reactions of α,β-unsaturated aldehydes such as ( E )-cinnamaldehyde and 2- or 4-methoxycinnamaldehyde with trimethylsilyl cyanide in the presence of a catalytic amount of a Lewis base such as TTMPP and DBU afforded the corresponding saturated carboxylic acids after hydrolysis.

Reaction of D-glycals with azidotrimethylsilane.

The treatment of 2,3,4,6-tetra-O-acetyl-1,5-anhydro-D-arabino-hex-1-enitol with azidotrimethylsilane by the aid of a catalytic amount of Yb(OTf)(3) afforded 2,4,6-tri-O-acetyl-2,3-dideoxy-alpha-D-erythro-hex-2-enopyranosyl azide in high yield.

Palladium-catalyzed stereoselective C-glycosidation of unprotected enones derived from d-glucal with trimethylsilyl cyanide

Abstract Acetylated and unprotected enones derived from d -glucal reacted with trimethylsilyl cyanide in the presence of a catalytic amount of a palladium compound in 1,4-addition fashion to afford the corresponding 3-keto-glycosyl cyanides in high yield and in high α-selectivity.

Thermal C-glycosylation of d-glucal with trimethylsilyl cyanide

The treatment of 3,4,6-tri-O-acetyl-D-glucal and unprotected D-glucal with trimethylsilyl cyanide, under thermal conditions in the absence of catalyst, afforded the corresponding 2,3-unsaturated glycosyl cyanides in high yield.

C-Glycosidation of unprotected d-glycals with trimethylsilyl cyanide

Unprotected glycals reacted with trimethylsilyl cyanide in the presence of a catalytic amount of a palladium compound to yield the 2,3-unsaturated glycosyl cyanides in high yield and in alpha-selectivity.

Metal-catalyzed transformation of D-glucal to optically active furan diol

The treatment of D-glucal with a catalytic amount of Sm(OTf)3 or RuCl2(PPh3)3 in the presence of 1 equiv. of H2O afforded optically active furan diol in good yield under mild conditions.

Tris(2,4,6-Trimethoxyphenyl)phosphine: Base Catalyst in the Transformation of α,β-Unsaturated Aldehydes to Saturated Carboxylic-Acid Derivatives

We have focused on the basicity of Tris(2,4,6-trimethoxyphenyl)phosphine (TTMPP) in organic synthesis. To extend the utility of TTMPP, we examined the reaction of α,β-unsaturated aldehydes with trimethylsilyl cyanide in the presence of TTMPP. Furthermore, to clarify the basic character of TTMPP, we measured 31P NMR of TTMPP and related compounds. First, the reaction of cinnamaldehydes with trimethylsilyl cyanide in the presence of a catalytic amount of TTMPP afforded the corresponding saturated carboxylic acids after hydrolysis with 1M HCl. Treatment of the reaction mixture with alcohols or amines instead of 1M HCl gave the corresponding saturated esters and amides, respectively. As a result of studies of the reaction mechanism, it was revealed that the reaction proceeded via silylcyanation of α,β-unsaturated aldehydes with trimethylsilyl cyanide to produce trimethylsilyl ethers of cyanohydrin and subsequent isomerization that formed α-trimethylsiloxy vinyl cyanides, which were hydrolyzed to give saturated carboxylic acids.

HF–pyridine promoted Friedel–Crafts type arylation of 2-acetoxy-D-glucal. Stereoselective synthesis of 1-arylhex-3-enopyranosiduloses

A variety of aromatic substrates were treated with 2-acetoxy-D-glucal in the presence of HF–pyridine to give 1-arylhex-3-enopyranosiduloses in high yield and in high α-selectivity.