Catalytic cycloalumination in steroid chemistry: The introduction of a spirotetrahydrofuran or spirotetrahydroselenophene moiety into a 3′-methylene-(5α)-spirocholestane-3,1′-cyclobutane molecule
摘要:
Cycloalumination of 3'-methylene-(5 alpha)-spirocholestane-3,1'-cyclobutane with triethylaluminum catalyzed by Cp2ZrCl2 was accomplished for the first time to give (5 alpha)-spirocholestane-3,1'-(6'-ethyl-6'-aluminaspiro [3.4] octane) in 89%. The latter, without isolation, was converted into spirotetrahydroselenophene or spirotetrahydrofuran. (C) 2012 Elsevier Inc. All rights reserved.
Synthesis and transformations of metallacycles 42. Cp2ZrCl2-Catalyzed cycloalumination of 3-methylidenespiro[cyclobutane-1,3′-(5′α)-cholestane] with Et3Al