Alkoxycarbonylnitrenes as selective intramolecular CH-insertion reagents in alicyclic chemistry
Abstract
Intramolecular CH-insertion of cyclohexyl, cis- and trans-4-t-butylcyclohexyl, and cis- and trans-2-methylcyclohexyl nitrenoformates have been studied. The nitrenes were generated by vapour-phase (spray) pyrolysis or solution thermolysis of the corresponding azides, or by photolysis of tetrachlorothienyl S,N-ylides derived from the azides. The product ratios were principally (and predictably) dependent upon reaction temperatures (and thus conformational equilibria), these varying in the range 10–500°C. 17-Substituted estrone-derived nitrenoformates inserted either into the 12β(from 17β) or 14α(from 17α) CH sites while 17-derivatives with the nitrene on the end of a long inert group abstracted hydrogen from the steroid B-ring.
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