Synthetic study of 1,7,9-trideoxypaclitaxel via sinenxan A
摘要:
Sinenxan A, a biosynthetic taxane, was converted into compound 9, a key intermediate of 1,7,9-trideoxypaclitaxel. Two special steps in this transformation are worthy of note: (1) regioselective removal of C-5-acetyl; and (2) stereoselective reduction of the 13-carbonyl group by transannular assistance from the C-4-hydroxyl. (C) 2002 Elsevier Science Ltd. All rights reserved.
Synthesis of 7,9-dideoxybaccatin IV analogs from sinenxan A
摘要:
Sinenxan A, a taxoid isolated from callus tissue cultures of Taxus yunnanensis was converted into 13-oxo-7,9-dideoxy-2-debenzoyl-2-acetyl-baccatin IV and 7.9-dideoxy-2-debenzoyl-4-deacetyl-baccatin IV, a key framework of 1,7,9-trideoxypaclitaxel. Several special steps in this transformation are worthy of note: (1) deoxygenation by treatment with hypophosphorous acid at C-14 positions (2) a highly regioselective O-deacetylation of taxane:, at C-5 position; and (3) stereoselective reduction of the 13-carbonyl group by transannular assistance from the C-4-hydroxyl. (c) 2005 Published by Elsevier Ltd.