SYNTHESIS OF N-TRIFLUOROACETYL-L-ACOSAMINE, N-TRIFLUOROACETYL-L-DAUNOSAMINE, AND THEIR 1-THIO ANALOGS

Article abstract of DOI:10.1016/0008-6215(86)85039-X

A simple and efficient route to N-trifluoroacetyl-L-acosamine (13), N-trifluoroacetyl-L-daunosamine (12), and their 1-thio analogues (18 and 20) is described.Stereoselective reduction of oxime 5 with borane, followed by trifluoroacetylation resulted in the arabino methyl glycoside (8), which, on mild acid hydrolysis gave N-trifluoroacetyl-L-acosamine (13) in an overall yield of 33percent, based on L-rhamnal (1).Upon oxidation of the C-4 hydroxyl group and stereoselective reduction of the resulting ketone 11, compound 8 of L-arabino configuration was converted into N-trifluoroacetyl-L-daunosamine (12) in a one-flask sequence with an overall yield of 28percent calculated for 1.Benzyl 1-thio-N-trifluoroacetyl-α-L-acosaminide (18) was synthesized from enone 2 on Michael-type addition of phenylmethanethiol, followed by oximation, stereoselective reduction with borane and subsequent trifluoroacetylation. 4-O-Acetyl-1-S-acetyl-N-trifluoroacetyl-1-thio-β-L-daunosamine 20 was prepared from 12 via the corresponding glycosyl chloride derivative.