Reaction of Hex-1-enopyranose-3-uroses with Organometallic Reagents. Regio- and Stereoselective Introduction of Allylic Substituents on Pyranose Ring

Abstract

4,6-O-Benzylidene-1,2-dideoxy-d-threo-hex-1-enopyranose-3-urose reacted with allylic organometallic reagents, CH2=CR–CH2–Metal [R = H or CH3; Metal = MgCl, AlEt2, or Ti(OPri)3], to selectively give 4,6-O-benzylidene-1,2-dideoxy-3-C-(2-propenyl- or 2-methyl-2-propenyl)-d-lyxo-hex-1-enopyranose. On the other hand, the erythro isomer gave 3-C-(2-propenyl- or 2-methyl-2-propenyl)-d-arabino-hex-1-enopyranose and the corresponding ribo isomer in a ratio ranging from 1 : 1 to 10 : 1