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N,N-DIIsopropyl-N-phosphonyl imines lead to efficient asymmetric synthesis of aziridine-2-carboxylic esters.

ABSTRACT: Highly diastereoselective asymmetric synthesis of chiral aziridine-2-carboxylic esters is reported for 20 examples with good yields (51-87%) and excellent diastereoselectivities (>99:1 dr for most cases). The modified N-phosphonyl imines have proven to be superior to previous imine auxiliaries for the aza Darzens reaction by using a secondary isopropyl group to replace the primary benzyl group for N,N-diamino protection. In the meanwhile, a special operation by slowly adding the pre-cooled imine solution at -78 °C into the preformed ?-bromo lithium enolate mixture at this temperature in the presence of 4 Å molecular sieves was found to be crucial in terms of yields and diastereoselectivity. The present method can provide an easy and general access to ?-hydroxy ?-amino acids and other important amino building blocks.

SUBMITTER: Kattamuri PV

PROVIDER: S-EPMC3653188 | biostudies-literature | 2013 May

REPOSITORIES: biostudies-literature

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N,N-DIIsopropyl-N-phosphonyl imines lead to efficient asymmetric synthesis of aziridine-2-carboxylic esters.

Kattamuri Padmanabha V PV Xiong Yiwen Y Pan Yi Y Li Guigen G

Organic & biomolecular chemistry 20130501 20

Highly diastereoselective asymmetric synthesis of chiral aziridine-2-carboxylic esters is reported for 20 examples with good yields (51-87%) and excellent diastereoselectivities (>99:1 dr for most cases). The modified N-phosphonyl imines have proven to be superior to previous imine auxiliaries for the aza Darzens reaction by using a secondary isopropyl group to replace the primary benzyl group for N,N-diamino protection. In the meanwhile, a special operation by slowly adding the pre-cooled imine ...[more]

PMID: 23563304

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