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.
Size-Exclusion Borane-Catalyzed Domino 1,3-Allylic/Reductive Ireland-Claisen Rearrangements: Impact of the Electronic and Structural Parameters on the 1,3-Allylic Shift Aptitude
reductive Ireland–Claisenrearrangement through borane‐mediated hydrosilylation is reported. The method employs a borane catalyst with a special structural design and affords access to synthetically relevant products with high diastereoselectivity. Depending on electronic and structural parameters, the reaction can be coupled with a 1,3‐allylic shift, thus the valence isomer of the Ireland–Claisen product