ChemInform Abstract: Conformational Design for 13α‐Steroids.

Abstract

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C–H functionalization logic in total synthesis

“…Shair and Giannis both made effective use of Scho¨necker's copper-mediated directed C-H hydroxylation methodology to quickly install the necessary oxidation state at C-12 of their respective steroidal skeletons, 82 and 85, without overoxidation to the ketone (Scheme 22). [57][58][59] In this reaction, copper chelates to the pyridyl imine directing group, which is believed to be oxidized to a bridged copper-oxo species that can insert an oxygen atom into the C-H bond of 83 and 86. This powerful reaction allowed the synthetic sequence to begin with readily available commercial steroids that could then be elaborated to the much more complex and rearranged products cephalostatin 1 (84) and cyclopamine (87).…”

Steroids: reactions and partial synthesis

“…44 The conformational analysis of some 13α-estra-1,3,5(10)-trienes bearing different C-16 and C-17 substituents, e.g. 15, has shown 45 that ring C can exist in a twisted boat conformation.…”