Remarkable beta-selectivity in the synthesis of beta-1-C-arylglucosides: stereoselective reduction of acetyl-protected methyl 1-C-arylglucosides without acetoxy-group participation.

An efficient and practical process to generate beta-C-arylglucoside derivatives was achieved. The process described involves Lewis acid mediated ionic reduction of a peracetylated 1-C-aryl methyl glucoside derived from the addition of an aryl-Li to selectively protected delta-D-gluconolactone. The reduction of the 2-acetoxy-1-C-oxacarbenium ion intermediates proceeds with a high degree of selectivity to give beta-C-arylglucosides without 2-acetoxy group participation. Furthermore, during the reduction process we also identified an unprecedented critical role of water. By changing from the usual benzyl ether protecting groups because of cost and chemical compatibility concerns, the new process is made additionally efficient and highly selective.

Efficient asymmetric synthesis of the vasopeptidase inhibitor BMS-189921.

[reaction: see text] An efficient asymmetric synthesis of the vasopeptidase inhibitor BMS-189921 was accomplished. Two short enantioselective syntheses of the common key intermediate (S)-alpha-aminoazepinone 6b were developed. Olefin 3 was converted to 6b via asymmetric hydrogenation. Alternatively, enyne 12 was converted to racemic alpha-aminoazepinone 15b, which was transformed to 6b by a practical dynamic resolution.

Confirmation of the structure of tetra-O-(tert-butyldimethylsilyl)-D-glucono-1,4-lactone formed by silylation of D-glucono-1,5-lactone.

The structure of tetra-O-(tert-butyldimethylsilyl)-D-glucono-1,4-lactone made by the silylation of D-glucono-1,5-lactone has been confirmed by single-crystal X-ray analysis.