The asymmetric CHinsertion of α‐diazoesters into 1‐alkynes was achieved using chiral cationic guanidinium salts and copper(I) complexes. Optically active 2,4‐disubstituted allenoates were generated under mild reaction conditions from various α‐diazoesters and 1‐alkynes in high yield (up to 99 %) and enantioselectivity (up to 97:3 e.r.). Control experiments excluded the possibility of an asymmetric
We present a new [3+2] cycloaddition reaction between alkyl–acceptor diazoalkanes under visible light irradiation. By employing easily accessible alkyl–acceptor-type diazoalkanes or their precursor hydrazones as both 1,3-dipoles and dipolarophiles, a diverse range of pyrazoline derivatives featuring a quaternary center have been efficiently synthesized in a predictable manner, with excellent functional
In the presence of the L/Y(OTf)3 catalyst, the first catalyticasymmetric homologation of α‐ketoesters with α‐alkyl‐α‐diazoesters through either a 1,2‐aryl or 1,2‐alkyl shift was accomplished. Highlyfunctionalized succinate derivatives containing a quaternary stereocenter were obtained in excellent yield and enantioselectivity under mild reaction conditions. Tf=trifluoromethanesulfonyl.