Synthesis of ferrocene-labeled steroids via copper-catalyzed azide–alkyne cycloaddition. Reactivity difference between 2β-, 6β- and 16β-azido-androstanes
摘要:
Copper-catalyzed cycloaddition of steroidal azides and ferrocenyl-alkynes were found to be an efficient methodology for the synthesis of ferrocene-labeled steroids. At the same time, a great difference between the reactivity of 2 beta- or 16 beta-azido-androstanes and a sterically hindered 6 beta-azido steroid toward both ferrocenyl-alkynes and simple alkynes, such as phenylacetylene, 1-octyne, propargyl acetate and methyl propiolate, was observed. (C) 2012 Elsevier Inc. All rights reserved.
Heterogeneouscoppercatalysts were prepared by the deposition of CuI on a hybrid material consisting of silica and a polymer with imidazolium moieties. The solid materials were characterised using solid‐phase NMR, Fourier transform infrared, Raman and X‐ray photoelectron spectroscopies and Brunauer–Emmett–Teller measurements. The formation of copper–carbene complexes was proved from Raman spectra