Semisynthetic ε-(iso)rhodomycins: a new glycosylation variant and modification reactions
作者:Cenek Kolar、Günther Kneissl、Ursula Knödler、Konrad Dehmel
DOI:10.1016/0008-6215(91)80147-f
日期:1991.1
Synthesis of 7-O-(3-amino-2,3,6-trideoxy-alpha-L-lyxo-hexopyranosyl)-e-(iso)rhodomycinones 16 and 17, and their 3'-morpholino derivatives are described. Glycosylation (trimethylsilyl triflate, 10:1 dichloro-methane-acetone, -35-degrees-) of 1-O-tert-butyldimethylsilyl-2,3,6-trideoxy-4-O-p-nitrobenzoyl-?? 3-trifluorace-tamido-beta-L-lyxo-hexopyranose (4) with e-rhodomycinone (e-RMN, 5) or e-isorhodomycinone (e-isoRMN, 6) afforded 7-O-alpha-glycosyl-e-RMN (9) and -e-isoRMN (12) in high yield. The glycosyl donors 2,3,6-trideoxy-4-O-p-nitrobenzoly-3-trifluoroacetamido-L-lyxo-hexopyranose (2) or its 1-O-trimethylsilylated alpha-anomer 3 were less suitable for the glycosylation of these aglycons. Saponification of 9 and 12 provided 16 and 17, respectively, which reacted with various 2,2'-oxydiacetaldehydes under conditions of reductive alkylation to give 3'-morpholinyl-e-(iso)rhodomycins.