A chemoselective Reformatsky–Negishi approach to α-haloaryl esters
摘要:
A practical synthesis of alpha-haloaryl esters has been achieved via a chemoselective Negishi coupling of poly-halogenated aromatics and Reformatsky reagents in the presence of catalytic Pd(dba)(2) and Xantphos. This chemistry tolerates a variety of aryl halides and was successfully applied to the synthesis of Ibuprofen. The alpha-haloaryl ester products, exemplified by ethyl 2-(4-bromo-2-chlorophenyl)acetate (3a), can be further functionalized via palladium or copper catalysis to afford an array of a-aryl esters. (C) 2014 Elsevier Ltd. All rights reserved.
Aromatic Claisen Rearrangements of Benzyl Ketene Acetals: Conversion of Benzylic Alcohols to (
<i>ortho</i>
‐Tolyl)acetates
作者:Jed M. Burns、Elizabeth H. Krenske、Ross P. McGeary
DOI:10.1002/ejoc.201601354
日期:2017.1.10
Claisen rearrangements of benzyl vinyl ethers are much less facile than those of aliphatic allyl vinyl ethers, and their synthetic utility has remained relatively unexplored. A one-pot procedure is reported for the generation and Claisen rearrangement of benzyl vinyl ethers that contain an activating α-alkoxy substituent on the vinyl group. A [3,3]-sigmatropic mechanism was supported by trapping of the