Sulfonyl Acetylenes and phosphaalkenes
Shameem and Keyhans paper got accepted in Chemistry - A European Journal.
Direct, sequential and stereoselective alkynylation of C,C-dibromophosphaalkenes
Muhammad A. Shameem, Keyhan Esfandiarfard, Elisabet Öberg, Sascha Ott,* and Andreas Orthaber
The first direct alkynylation of C,C-dibromo-phosphaalkenes by a reaction with sulfonylacetylenes is reported. Alkynylation proceeds selectively in trans position relative to the P-substituent to afford bromoethynylphosphaalkenes. Owing to the absence of transition metals in the procedure, the previously observed conversion of dibromophosphaalkenes into phosphaalkynes through the phosphorus analogue of the Fritsch-Buttenberg-Wiechell rearrangement is thus suppressed. The bromoethynyl-phosphaalkenes can subsequently be converted to C,C-diacetylenic, cross-conjugated phosphaalkenes following a Sonogashira coupling protocol in good overall yields. By using the newly described method, full control over the stereochemistry at the P=C double bond is achieved. The substrate scope of this reaction is demonstrated for different dibromophosphaalkenes as well as different sulfonylacetylenes.