Synthesis of 3,4-Di-O-benzyl-1-O-methyl-L-galactitol, a key precursor of the C33-C37 fragment of calyculins
2001
Cironi Pablo | Varela Oscar
3,4-Di-O-benzyl-1-O-methyl-L-galactitol (3) has been synthesized in a seven step sequence starting from 1,2:3,4-di-O-isopropylidene-alpha-D-galactopyranose (4). The synthesis involves the methyllation of HO-6 of 4, followed by methanolysis to the mixture of the corresponding methyl 6-O-methyl-alpha-D-galactopyranoside (6, major product) and the beta-furanoside analog (8). Compound 6 was converted into the 3,4-O-isopropylidene derivative 9, and the free HO-group was protected as the methoxyethoxymethyl (MEM) ether. Chemoselective removal of the acetonide by hydrolysis, followed by benzylation gave the methyl 3,4-di-O-benzyl-2-O-methoxyethoxymethyl-6- O-methyl-alpha-D-galactopyranoside (12). Simultaneous acid hydrolysis of the methyl glycoside and MEM group of 12 led to 13, which was then reduced with sodium borohydride to the target molecule 3.
Показать больше [+] Меньше [-]Ключевые слова АГРОВОК
Библиографическая информация
Эту запись предоставил AVANO