Camphor imines

Asymmetric Michael Additions of Enantiopure Camphor Imines.. . 774... 

One problem in the anti-selective Michael additions of A-metalated azomethine ylides is ready epimerization after the stereoselective carbon-carbon bond formation. The use of the camphor imines of ot-amino esters should work effectively because camphor is a readily available bulky chiral ketone. With the camphor auxiliary, high asymmetric induction as well as complete inhibition of the undesired epimerization is expected. The lithium enolates derived from the camphor imines of ot-amino esters have been used by McIntosh s group for asymmetric alkylations (106-109). Their Michael additions to some a, p-unsaturated carbonyl compounds have now been examined, but no diastereoselectivity has been observed (108). It is also known that the A-pinanylidene-substituted a-amino esters function as excellent Michael donors in asymmetric Michael additions (110). Lithiation of the camphor... 

Camphor and camphor-derived analogues are used frequently as chiral auxiliaries in asymmetric synthesis (cf Chapter 23). There have been numerous reports in the use of camphor imine as templates to direct enantioselective alkylation for the synthesis of a-amino acids, a-amino phos-phonic acids, a-substituted benzylamines, and a-amino alcohols (e.g., Scheme 5.9).43 47 Enantiomeric excesses of the products range from poor to excellent depending on the type of alkyl halides used. 

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