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Stereoselectivity of the Radical Reductive Alkylation of Enamines: Importance of the Allylic 1,3‐Strain Model
Author(s) -
Schubert Serge,
Renaud Philippe,
Carrupt PierreAlain,
Schenk Kurt
Publication year - 1993
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19930760707
Subject(s) - chemistry , cyclohexanone , stereoselectivity , allylic rearrangement , alkylation , ketone , propiophenone , strain (injury) , medicinal chemistry , stereochemistry , organic chemistry , catalysis , medicine
Radical addition to enamines using Bu 3 SnH as reducing agent are reported ( Schemes 2 and 4 ). The diastereoselectivity of these reactions was examined in different systems ( Tables 1 and 2 ). Enamines derived from cyclic ketones such as cyclohexanone were alkylated with high diastereoselectivity with preferential formation of the cis ‐disubstituted cycloalkanes. In acyclic systems such as enamines derived from propiophenone and diethyl ketone, moderate to high stereoselectivities were observed in the H‐abstraction step. A model based principally on minimization of allylic 1,3‐strain ( A 1,3 strain) was deduced from the experimental results and semi‐empirical (AM1) calculations.