Enantioselective α-Alkenylation of Aldehydes with Boronic Acids via the Synergistic Combination of Copper(II) and Amine Catalysis
摘要:
The enantioselective alpha-alkenylation of aldehydes has been accomplished using boronic acids via the synergistic combination of copper and chiral amine catalysis. The merger of two highly utilized and robust catalytic systems has allowed for the development of a mild and operationally trivial protocol for the direct formation of alpha-formyl olefins employing common building blocks for organic synthesis.
Direct Enantioselective and Regioselective Alkylation of β,γ-Unsaturated Carboxylic Acids with Chiral Lithium Amides as Traceless Auxiliaries
作者:Kai Yu、Bukeyan Miao、Wenqi Wang、Armen Zakarian
DOI:10.1021/acs.orglett.9b00587
日期:2019.3.15
Efficient asymmetric alkylation of β,γ-unsaturated carboxylicacids without prior functionalization is enabled by chiral lithium amides. Enantioselectivity is imparted by a putative mixed lithium amide–enediolate aggregate that acts a traceless auxiliary formed in situ, allowing for a direct asymmetric alkylation and a simple recovery of the chiral reagent.
Highly Diastereoselective Michael Additions onto Dienyl Bis-Sulfoxides
作者:Louis Fensterbank、Max Malacria、Franck Brebion、Jean Philippe Goddard
DOI:10.1055/s-2005-872089
日期:——
cinnamaldehyde furnished bis-sulfoxide dienyl derivative 5, a remarkable 1,4-Michael acceptor that can lead in a highly diastereoselective manner to vinylcyclopropyl adducts. In a chelating mode of reactivity using a methylcopper reagent, a complete reversal of stereoselectivity is observed giving an enantiopure β,γ-unsaturated methyl ester intermediate that is used in the synthesis of cryptophycin