gave a mixture of a 22-ethyl ketal with a hemiketal. Both undergo elimination reactions very readily to yield the Δ22-bond isomer of pseudotigogenin diacetate. The conversions are reversible and are catalyzed by acetic acid and in neutral solution by calcium sulfate and other surfaces. Alkaline hydrolysis followed by cyclization with acetic acid converted both the ketal and the Δ22-olefin to tigogenin
A new experimental protocol has been established for the Clemmensen reduction of diosgenin and kryptogenin with the aim to prepare deuterated isotopomers of (25R)-26-hydroxycholesterol. Uncontrolled deuteration has been achieved from diosgenin, whereas [16,16,22,22,23,232 H-2(6)]-(25R)-26-hydroxycholesterol (1) can be synthesized from kryptogenin. (C) 2004 Elsevier Inc. All rights reserved.
STEROIDAL SAPOGENINS. XVIII.<sup>1</sup> EXPERIMENTS IN THE 5,6-DIHYDROKRYPTOGENIN SERIES
作者:A. L. NUSSBAUM、A. SANDOVAL、G. ROSENKRANZ、CARL DJERASSI
DOI:10.1021/jo01137a015
日期:1952.3
Steroidal Sapogenins. III. 16-Alkyl-sapogenins
作者:St. Kaufmann、G. Rosenkranz
DOI:10.1021/ja01178a516
日期:1949.10
Steroidal Sapogenins. IX.<sup>1</sup> Oxidation of Δ<sup>5,16,20(22)</sup>-Furostatriene-3β,26-diol<sup>2</sup>