Chiral phosphoramide-catalyzed enantioselective addition of allylic trichlorosilanes to aldehydes. Preparative and mechanistic studies with monodentate phosphorus-based amides

Scott E. Denmark, Jiping Fu, Diane M. Coe, Xiping Su, Norman E. Pratt, Brian D. Griedel

Research output: Contribution to journalArticlepeer-review

Abstract

The addition of allylic trichlorosilanes to benzaldehyde promoted by chiral phosphoramides to give the enantioenriched homoallylic alcohol has been investigated. In a survey of Lewis bases as activators for the addition of allyltrichlorosilane to benzaldehyde, phosphorus-based amides have been found to be the most effective promoters. To achieve asymmetric induction, chiral phosphoric triamides derived from chiral diamines have been developed and applied in the allylation reaction albeit with modest enantioselectivities. The addition of 2-butenylsilanes was highly diastereoselective, suggesting a closed, chairlike transition structure. A detailed mechanistic study has been carried out to probe into the origin of activation. From a combination of nonlinear effects and kinetics studies, the reaction was found to likely involve two phosphoramides in both the rate and stereochemistry determining steps. These studies provided the background for the development of highly selective and reactive catalysts.

Original languageEnglish (US)
Pages (from-to)1513-1522
Number of pages10
JournalJournal of Organic Chemistry
Volume71
Issue number4
DOIs
StatePublished - Feb 17 2006

ASJC Scopus subject areas

  • Organic Chemistry

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