Organophosphorus Compounds, 111 Phospha Ene Reactions of a P‐Chlorophosphaalkene as a Versatile and Powerful Enophile Building Block

Abstract

Abstract[Bis(trimethylsilyl)methylene]chlorophosphane (1) has proved to act as an extremely reactive enophile in phospha ene reactions with all‐carbon enes of differing constitutions and so provides a general approach to β,γ‐unsaturated chlorophosphanes. Thus, for example, 1 reacts even at room temperature or slightly elevated temperatures with the terminal alkenes 6a–c, the methylenecycloalkanes 6d, e, h, and the cycloalkenes 6f, g to furnish the corresponding allyl‐substituted chlorophosphanes 7a–h. Dimethylallene (8) undergoes addition to 1 to yield the phosphanyl‐substituted buta‐1,3‐diene 9 whereas allene (10) itself reacts with 1 by way of a previously unknown phospha ene reaction to give the propynyl‐substituted chlorophosphane 11. By contrast, the (chlorophosphanyl)allene 13 results from the reaction of 1 with but‐2‐yne (12). All of these group transfer reactions proceed chemo‐ and regioselectively with P/C bond formation. The constitutions of all the phospha ene adducts, which were isolated in satisfactory to good yields after purification by distillation, were unequivocally confirmed by analytical and spectroscopic methods.