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Formal Halo‐Meyer–Schuster Rearrangement of Propargylic Acetates through a Novel Intermediate and an Unexampled Mechanistic Pathway
Author(s) -
Sadhukhan Santu,
Baire Beeraiah
Publication year - 2019
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201901856
Subject(s) - stereoselectivity , yield (engineering) , reagent , chemistry , halo , lewis acids and bases , selectivity , stereochemistry , population , cascade , bond cleavage , catalysis , physics , organic chemistry , thermodynamics , demography , chromatography , quantum mechanics , galaxy , sociology
A formal, highly stereoselective halo‐Meyer–Schuster rearrangement of inactivated propargylic acetates to ( Z )‐α‐haloenones has been reported, under metal free conditions. This cascade process involves a new class of intermediate, i.e., α,α‐dihalo‐β‐acetoxyketones and mechanism to generate the α‐haloenones, employing water as Lewis base. The outcome of the reaction is temperature‐dependent, as room temperature, selectively provides α,α‐dihalo‐β‐acetoxyketones whereas reactions at 100 °C give direct access to α‐haloenones. Either type of product can be obtained in excellent yield. A suitable rationale for the observed high Z ‐selectivity for α‐haloenones (based on conformational population) and distinct reaction rates for various N ‐halosuccinimide (NXS) reagents (based on C−X bond strengths) has also been provided.