Selective Alkynylallylation of the C−C σ Bond of Cyclopropenes.

A Pd‐catalyzed regio‐ and stereoselective alkynylallylation of a specific C−C σ bond in cyclopropenes, using allyl propiolates as both allylation and alkynylation reagents, has been achieved for the first time. By merging selective C(sp2)‐C(sp3) bond scission with conjunctive cross‐couplings, this decarboxylative reorganization reaction features fascinating atom and step economy and provides an efficient approach to highly functionalized dienynes from readily available substrates. Without further optimization, gram‐scale products can be easily obtained by such a simple, neutral, and low‐cost catalytic system with high TONs. DFT calculations afford a rationale toward the formation of the products and indicate that the selective insertion of the double bond of cyclopropenes into the C‐Pd bond of ambidentate Pd complex and the subsequent nonclassical β‐C elimination promoted by 1,4‐palladium migration are critical for the success of the reaction. [ABSTRACT FROM AUTHOR]