Modified Iridoid Glycosides (Part-1): Syntheses of 4′-5′-unsaturated Iridoid Glycosides from Loganin and Arbortristoside-A

Abstract

A general method for preparing 4′,5′-unsaturated iridoid glycosides is described through Pyridinium Chloro Chromate (PCC) mediated oxidation of iridoids. Oxidation of partially protected derivatives of Loganin (1), 7-Dehydrologanin (2), and Arbortristoside-A (3) with PCC followed by NaBH₄ reductions furnished the title compounds (11, 8a, 8b, and 15). Deprotection of 11 gave 4′-5′unsaturated iridoid glycoside (12b).

Key Words:

• Loganin
• 7-Dehydrologanin
• Arbortristoside-A