Reversed stereochemical control in the presence of CeCl3 and TiCl4 in the Lewis acid mediated reduction of α-alkyl-β-keto esters by metal hydrides. A general methodology for the diastereoselective synthesis of syn- and anti-α-alkyl-β-hydroxy esters

Enrico Marcantoni, Sara Alessandrini, Marco Malavolta, Giuseppe Bartoli, Maria Cristina Bellucci, Letizia Sambri, Renato Dalpozzo

Research output: Contribution to journalArticlepeer-review

Abstract

The Lewis acid-mediated reduction of α-alkyl-β-keto esters has been shown to proceed by different stereochemical control depending on the nature of the metal atom. Strongly chelating TiCl4 led to the syn isomer in high diastereomeric excess in noncoordinating solvents (CH2Cl2) at -78 °C with BH3·py as reducing agent, while nonchelating CeCl3 gave a high excess of the anti isomer in coordinating solvents (THF) at the same temperature with lithium triethylborohydride (LiEt3BH) as reducing agent. The methodology has been successfully utilized for obtaining important synand anti-α-alkyl-β- hydroxy esters with high diastereoselectivity.

Original languageEnglish
Pages (from-to)1986-1992
Number of pages7
JournalJournal of Organic Chemistry
Volume64
Issue number6
DOIs
Publication statusPublished - Mar 19 1999

ASJC Scopus subject areas

  • Organic Chemistry

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