Glycosyl Imidates, 63. – Synthesis of the Sulfated Steroidal Glycosides Forbeside E3 and E1

✍ Scribed by Jiang, Zi-Hua ;Han, Xiao-Bing ;Schmidt, Richard R.

• Publisher: John Wiley and Sons
• Year: 1993
• Tongue: English
• Weight: 565 KB
• Volume: 1993
• Category: Article
• ISSN: 0947-3440
• DOI: 10.1002/jlac.1993199301191

✦ Synopsis

Abstract

Reaction of 6α‐hydroxy‐substituted steroids 7 and 8 with the 2‐O‐benzyl‐protected quinovosyl donors 4a, b afforded α,β‐mixtures of the glycosides 9a, b; with O‐acetyl‐protected donor 4c, due to neighboring group participation, exclusively β‐glycoside 9cβ was obtained. Similarly, reaction of donor 4c with 3β‐O‐silyl‐protected 6α‐hydroxy‐steroid 12 furnished β‐connected 6__O__‐quinovosyl derivative 14 in high yield. 3‐O‐Desilylation of 14 with TBAF and ensuing 3‐O‐sulfation with pyridine/sulfur trioxide complex yielded pyridinium sulfate derivative 17, which turned out to be rather unstable. Treatment of 17 with sodium methoxide in methanol gave in high yield forbeside E 3 (1) the physical data of which were in good agreement with literature reports. Diastereoselective reduction of the keto group in 18 with NaBH~4~ led preferentially to 19 which was deacetylated to afford forbeside E 1 (2).