Theoretical Evidence of Pyramidalized Bicyclic Serine Enolates in Highly Diastereoselective Alkylations
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Universidad de La Rioja
info
ISSN: 0947-6539
Year of publication: 2007
Volume: 13
Issue: 17
Pages: 4840-4848
Type: Article
More publications in: Chemistry - A European Journal
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Abstract
A new chiral serine equivalent and its enantiomer have been synthesized from (S)- and (R)-N-Bocserine methyl esters (Boc: tert-butyloxy-carbonyl). The use of these compounds as chiral building blocks has been demonstrated in the synthesis of α-alkyl α-amino acids by diastereoselective po tassium enolate alkylation reactions and subsequent acid hydrolyses. Theoretical studies were performed to eluci date the stereochemical outcome of both the formation of five-membered cyclic N,O-acetals and the subsequent alkylation process, which occurs with total retention of configuration. This feature could be explained in terms of the high degree of pyramidalization of enolate intermediates. © 2007 Wiley-VCH Verlag GmbH & Co. KGaA.