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Glycosyl Imidates, 63. – Synthesis of the Sulfated Steroidal Glycosides Forbeside E3 and E1
Author(s) -
Jiang ZiHua,
Han XiaoBing,
Schmidt Richard R.
Publication year - 1993
Publication title -
liebigs annalen der chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 0170-2041
DOI - 10.1002/jlac.1993199301191
Subject(s) - chemistry , glycosyl , glycoside , sulfation , stereochemistry , biochemistry
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 ).