通过使盐酸与两种差向异构的3-羟基-3-甲基-5α-胆甾烷反应,制得3α-氯-3β-甲基-和3β-氯-3α-甲基-5α-胆甾烷。用四甲基-1-氯乙烯基胺作为氯化剂,可以获得更好的收率和更清洁的转化率。两种3-甲基-5α-胆甾醇与三苯基膦-四氯化碳或三氯化磷-吡啶的反应生成了3-甲基-5α-胆甾-2-烯,3-甲基-5α-胆甾-3-烯和3-亚甲基-5α-胆甾烷。通过用(二乙基氨基)三氟化硫处理两个3-甲基-5α-胆甾烷-3-醇,获得了两个差向异构的3-氟-3-甲基-5α-胆甾烷。3-卤代-3-甲基-5α-胆甾烷的构型由它们的13个决定C nmr光谱。两种3-卤代-3-甲基-5α-胆甾烷差向异构体的可用性使800-400 cm -1区域的红外光谱得到了明确的解释。
A New Method for the Synthesis of<i>tert</i>-Alkyl Chlorides from<i>tert</i>-Alcohols
作者:David Crich、Simon M. Fortt
DOI:10.1055/s-1987-27832
日期:——
Tert-Alkyl chlorides 5 are prepared in good yield from the corresponding alcohols 1 in a facile two step synthesis. The method involves treatment of the corresponding crude oxalyl monochloride alkyl ester 2 with N-hydroxy-pyridine-2-thione sodium salt 3 in tetrachloromethane at reflux to give the bright yellow N-(alkoxyoxalyloxy) pyridine-2-thiones 4 which undergo decomposition to the chlorides 5 in good yield. The reaction is conveniently monitored by the loss of colour from the mixed anhydride.
Elimination reactions and configurations of 1-methylcyclohexyl derivatives, including steroid analogues
作者:D. N. Kirk、P. M. Shaw
DOI:10.1039/j39700000182
日期:——
this pattern: the results of dehydrohalogenation of the 3α-halogeno-3β-methyl derivatives (V) also appeared to be anomalous. Similar reactions of 1-methyl-4-t-butyl-cyclohexyl derivatives, and of 12-methylspirostan-12-yl compounds, indicate that the proportions of olefinic products may be decided as much by the ‘leavinggroup,’ and by the base employed, as by the conformational features of the compound