Regioselective ring opening of the chiral non-racemic furoindolizidinols. New entry to alkylindolizidinediol derivatives

New homochiral 6-ethyl-7,8-indolizidinediol derivatives, related to the bioactive dihydroxylated indolizidine alkaloids, are reported to be easily accessible in four or five steps from enantiopure 9-hydroxy-octahydrofuro[3,2-f]indolizin-6(2H)-ones in good overall yields and high diastereomeric purities. The simple procedure used herein involves a regiospecific THF-ring opening as a key step, in addition to the C-Br linkage reduction, and the alcohol deprotection followed by lactam reduction.