A Useful Divinyl Ketone Equivalent

Abstract

In our approach to steroids of the androstane 3,17-dione type, we utilized 5-chloropent-1-ene-3-one (2) as a synthetic equivalent of divinyl ketone (3).^1–3 We were able to achieve the conversion of 2 to a product of the type 4 by the consecutive use of two different Michael donors, XH and YH.⁴ While some success was realized with compound 2, it does not constitute a generally satisfactory solution. Thus, difficulties were often experienced in its preparation by the controlled monodehydrohalogenation of its precursor, 1. Moreover, under some basic conditions, 2 is dehydrohalogenated to varying extents, giving 3 itself, which, in our hands is not readily susceptible to differentiated reactions.