Addition of titanium ester enolates to aldimines containing a chiral α-methylbenzylamine moiety: synthesis of chiral syn-β-amino esters

Addition of titanium ester enolates to N-arylidene derivatives containing a (R)-α-methylbenzylamine moiety afforded (2S,3S,αR)-β-amino esters in 73–93% yields with 86:14 to 96:4 diastereomeric ratios.

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(2S,3S,αR)-Methyl 3-(N-(3,5-dinitrobenzoyl)-N-α-methylbenzyl)amino-3-phenyl-2-ethylpropionateC27H27N3O7De >98%[α]D25=+66.4 (c 1, CHCl3)Source of chirality: diastereoselective synthesisAbsolute configuration: (2S,3S,αR)

(2S,3S,αR)-Methyl 3-(N-(3,5-dinitrobenzoyl)-N-α-methylbenzyl)amino-3-phenyl-2-benzylpropionateC32H29N3O7De >96%[α]D25=+64.3 (c 1, CHCl3)Source of chirality: diastereoselective synthesisAbsolute configuration: (2S,3S,αR)

(2S,3S,αR)-Methyl 3-(N-(3,5-dinitrobenzoyl)-N-α-methylbenzyl)amino-3-phenyl-2-isopropylpropionateC28H29N3O7De >94%[α]D25=+47.1 (c 1, CHCl3)Source of chirality: diastereoselective synthesisAbsolute configuration: (2S,3S,αR)