Reactions with type I crotylboron compounds

The stereochemistry of the reactions of chiral carbonyl compounds with nucleophiles has been a topic of considerable theoretical and synthetic interest since the pioneering study by Cram appeared in 1952. The available predictive models focus entirely on the conformational and stereoelectronic demands of the chiral carbonyl substrate, the implicit assumption being that the relative stabilities of the competing transition states are determined only by stereoelectronics and the minimization of nonbonded interactions between the substituents on the chiral center and the nucleophile. These models totally ignore the possibility, however, that the geometric requirements of the nucleophile may also have an effect on reaction diastereoselectivity. Considerable evidence is now available, particularly in the reactions of Type I (Z)-crotylboronates and Z(0)-metal enolates, that the stereochemistry of the nucleophile is indeed an important issue that must be considered when assessing reaction diastereoselectivity. 

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See also in sourсe #XX -- [ , , , , , ]

See also in sourсe #XX -- [ , , , , , ]

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