Allylic gem‐dichlorides are shown to be efficient substrates for catalytic asymmetric allylboration of alkynes. The method employs a chiral NHC−Cu catalyst capable of generating in a single step chiral skipped dienes bearing a Z‐alkenyl chloride, a trisubstituted E‐alkenyl boronate and a bis‐allylic stereocenter with excellent levels of chemo‐, regio‐ enantio‐ and diastereoselectivity. This high degree of functionalization makes these products versatile building blocks as illustrated with the synthesis of several optically active compounds. DFT calculations support the key presence of a metal cation bridge ligand–substrate interaction and account for the stereoselectivity outcome.
Allylic gem‐dichlorides are shown to be efficient substrates for catalytic asymmetric allylboration of alkynes. The method employs a chiral NHC−Cu catalyst capable of generating in a single step chiral skipped dienes bearing a Z‐alkenyl chloride, a trisubstituted E‐alkenyl boronate and a bis‐allylic stereocenter with excellent levels of chemo‐, regio‐ enantio‐ and diastereoselectivity. This high degree of functionalization makes these products versatile building blocks as illustrated with the synthesis of several optically active compounds. DFT calculations support the key presence of a metal cation bridge ligand–substrate interaction and account for the stereoselectivity outcome.
A catalytic asymmetric reaction between allenes, bis(pinacolato)diboron, and allylic gem-dichlorides is reported. The method involves the coupling of a catalytically generated allyl copper species with the allylic gem-dichloride and provides chiral internal 1,5-dienes featuring (Z)-configured alkenyl boronate and alkenyl chloride units with high levels of chemo-, regio-, enantio-, and diastereoselectivity. The synthetic utility of the products is demonstrated with the synthesis of a range of optically active compounds. DFT calculations reveal key noncovalent substrate−ligand interactions that account for the enantioselectivity outcome and the diastereoselective formation of the (Z)-alkenyl chloride.
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