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Aldol Reactions between L ‐Erythrulose Derivatives and Chiral α‐Amino and α‐Fluoro Aldehydes: Competition between Felkin–Anh and Cornforth Transition States
Author(s) -
DíazOltra Santiago,
Carda Miguel,
Murga Juan,
Falomir Eva,
Marco J. Alberto
Publication year - 2008
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.200800956
Subject(s) - aldol reaction , chemistry , transition state , organic chemistry , stereochemistry , medicinal chemistry , catalysis
Both matched and mismatched diastereoselection have been observed in aldol reactions of a boron enolate of a protected L ‐erythrulose derivative with several chiral α‐fluoro and α‐amino aldehydes. Strict adherence to the Felkin–Anh model for the respective transition structures does not account satisfactorily for all the observed results, as previously observed in the case of α‐oxygenated aldehydes. In some cases, only the Cornforth model provides a good explanation. The factors that influence this dichotomy are discussed and a general mechanistic model is proposed for aldol reactions with α‐heteroatom‐substituted aldehydes. Additional support for the model was obtained from density functional calculations.