Merrifield resin-supported dipeptide

The synthesis of a novel Merrifield resin-supported dipeptide Pro-Ala-O-P, derived from proline and alanine, was reported by Wang and Yan with the aim of being used as an organocatalyst in asymmetric aldol reactions of ketones with aldehydes. " Indeed, this supported dipeptide was found to be an efficient catalyst to promote the asymmetric aldol reaction under neat conditions between aromatic aldehydes and cyclic ketones, generating the corresponding aldol products with moderate to high yields and diastereoselectivities of up to 80% de combined with good enantioselectivities of up to 95% ee, as shown in Scheme 2.18. Moreover, this catalyst could be used for seven times with only a minor decrease in product yields, but maintained stereoselectivities. 

Scheme 2.18 Aldolisations of ketones with aldehydes catalysed by Merrifield resin-supported dipeptide.

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