Acyclic dicarboxylic acid esters

Table 11.1-7. a-Chymostrypsin-catalyzed enantiotopos-differentiating hydrolysis of prochiral cyclic dicarboxylic acid esters, acyclic dicarboxylic acid esters and cyclic diol diacetates and enantiomer-differentiating hydrolysis of racemic carboxylic acid esters in aqueous solution. 

Finally, a direct Mannich-type approach has been developed for the enantioselective synthesis of hydrazines and amines (Scheme 16.40). Thus, by trapping with alkyl diazoacetates some in s/iw-generated acyclic azomethine imines, in the presence of axially chiral dicarboxylic acids, a series of a-diazo-(3-hydrazino esters were obtained with excellent enantioselectivities [86]. 

Acyclic weso-dicarboxylic esters with a succinic and glutaric acid backbone were also good substrates for PLE [224] and a-chymotrypsin (Scheme 2.28) [225]. Interestingly, an additional hydroxy group in the substrate led to an enhancement of the chiral recognition process in both cases. 

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