Sequential transhalogenation and Heck reaction for efficient access to dioxo-tetrasubstituted 2,4 E,E-dienes: synthesis of segment C1–C6 of apoptolidin
摘要:
Efficient access to dioxo-tetrasubstituted 2,4 E,E-dienes is developed in three steps from commercially available starting materials via sequential trans halogenation and Heck reaction, which provides potentially useful synthons for the synthesis of a tetrasubstituted conjugated diene structure in complex molecules. Thereby, segment C1-C6 of apoptolidin is synthesized. (c) 2006 Elsevier Ltd. All rights reserved.
A three‐component palladium‐catalyzed reaction sequence has been developed in which γ‐substituted α,β‐unsaturated products are obtained in a single flask by an α‐alkenylation with either a subsequent γ‐alkenylation or γ‐arylation of a ketoneenolate. Coupling of a variety of electronically and structurally different components was achieved in the presence of a Pd/Q‐Phos catalyst (2 mol %), usually
α-Diazo-β-ketonitriles: Uniquely Reactive Substrates for Arene and Alkene Cyclopropanation
作者:Roger R. Nani、Sarah E. Reisman
DOI:10.1021/ja401610p
日期:2013.5.15
An investigation of the intramolecular cyclopropanation reactions of alpha-diazo-beta-ketonitriles is reported. These studies reveal that alpha-diazo-beta-ketonitriles exhibit unique reactivity in their ability to undergo arene cyclopropanation reactions; other similar acceptor acceptor-substituted diazo substrates instead produce mixtures of C-H insertion and dimerization products. alpha-Diazo-beta-ketonitriles also undergo highly efficient intramolecular cyclopropanation of tri- and tetrasubstituted alkenes. In addition, the alpha-cyano-alpha-ketocyclopropane products are demonstrated to serve as substrates for S(N)2, S(N)2', and aldehyde cycloaddition reactions.