Diastereoselective Nucleophilic Addition to Aldehydes with Polar alpha- and alpha,beta-Substituents

• The stereoselectivities obtained in Lewis acid-promoted Mukaiyama aldol additions and Sakurai allylations of mono-, and syn- and anti-disubstituted aldehydes possessing various polar alpha- and beta-substituents under non-chelating conditions are presented. The stereochemical outcome in the nucleophilic addition to alpha-substituted aldehydes containing an alpha-benzyloxy, alpha-fluoro or alpha-sulfonamide substituent are accurately predicted by current stereoinduction models. In contrast, the selectivitites obtained from addition of sterically demanding nucleophiles to alpha-chloro-substituted aldehydes cannot be rationalized by the same models and an alternative is discussed. The stereochemichal outcome in the additions to alpha, beta-disubstituted aldehydes is more complex and cannot be predicted using current models.

Ämnesord

NATURVETENSKAP  -- Kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences (hsv//eng)

Nyckelord

aldol reaction

allylation

diastereoselectivity

induction model

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