Ligand-Controlled Stereodivergent Hydroalkynylation of Purine Allenamines to Access Functionalized - and -1,3-Enynes.

Herein, we report an easily tunable and regioselective Pd-catalyzed allene-alkyne coupling protocol for the stereodivergent synthesis of - and -1,3-enynes using purine allenamine by a simple switch of ligands P(-tolyl)Ph and Boc-Phe-OH. For the first time, we have explored mono--protected amino acids (MPAAs) as ligands in allene-alkyne coupling to furnish -1,3-enynes selectively. This protocol streamlined the access to chiral 1,3-enynes and addressed the long-standing stereoselectivity challenges associated with 1,3-enynes from allene-alkyne coupling.