Rate Dependence on Inductive and Resonance Effects for the Organocatalyzed Enantioselective Conjugate Addition of Alkenyl and Alkynyl Boronic Acids to β-Indolyl Enones and β-Pyrrolyl Enones
作者:Amy Boylan、Thien S. Nguyen、Brian J. Lundy、Jian-Yuan Li、Ravikrishna Vallakati、Sasha Sundstrom、Jeremy A. May
DOI:10.3390/molecules26061615
日期:——
Two key factors bear on reaction rates for the conjugate addition of alkenylboronicacids to heteroaryl-appended enones: the proximity of inductively electron-withdrawing heteroatoms to the site of bond formation and the resonance contribution of available heteroatom lone pairs to stabilize the developing positive charge at the enone β-position. For the former, the closer the heteroatom is to the
Construction of macrocyclic trienes by diene-ene RCM of tetraenes was examined. In the reactions, macrocyclic trienes were obtained as a mixture of two isomers with E,Z-configured 1,3-diene moiety. The formation of two isomers can be understandable by the E–Z isomerization of the initially generated ruthenium–alkenyl carbene intermediate.
Asymmetric Synthesis of N‐Fused 1,3‐Oxazolidines via Pd‐Catalyzed Decarboxylative (3+2) Cycloaddition
作者:Jong‐Un Park、Hye‐In Ahn、Ho‐Jun Cho、Zi Xuan、Ju Hyun Kim
DOI:10.1002/adsc.201901497
日期:2020.4.27
Efficient synthesis of optically active N‐fused 1,3‐oxazolidines containing quaternary and tertiary stereocenters was achieved via Pd‐catalyzed asymmetric (3+2) cycloadditions of sulfamate‐derived cyclic imines and vinylethylene carbonates. Using a chiral phosphoramidite ligand, the cycloadditions proceeded effectively providing sulfamidate‐fused 1,3‐oxazolidines in high yields (up to 96%) with stereoselectivities