Synthesis of skipped enynes via phosphine-promoted couplings of propargylcopper reagents

An electron-rich phosphine additive is critical and sufficient for propargyl-selective couplings of propargylcopper reagents and alkenyl halides. This method is complementary to those previously described, in which high allenyl selectivity is observed in analogous coupling reactions. While the basis of the phosphine effect requires further investigation, the information gained in these studies enables the synthesis of complex molecules by way of skipped enyne intermediates.