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Asymmetric Carbamoyl Anion Additions to Chiral N-Phosphonyl Imines via the GAP Chemistry Process and Stereoselectivity Enrichments.

ABSTRACT: Carbamoyl anions were found to smoothly react with chiral N-phosphonyl imines in toluene at -78 °C to r.t. using LiHMDS as the base. Group-assisted purification (GAP) has been utilized to give the pure amides without using column chromatography or recrystallization. The asymmetric reaction resulted in chiral N-phosphonyl amino amides with good to excellent yields (71-99%) and good crude diastereoselectivities (dr 84:16-95:5). In this GAP procedure, the crude solids are washed with diethyl ether to afford the pure products, as revealed by (1)H NMR analysis; GAP washing consistently increases the diastereopurity of the products, resulting in excellent diastereoselectivities, often with final dr > 99:1. Interestingly, the diastereoenriched products can be obtained either in the ether solution or as the suspended solid, depending on the substrate.

SUBMITTER: Seifert CW

PROVIDER: S-EPMC4285137 | biostudies-literature | 2015 Jan

REPOSITORIES: biostudies-literature

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Asymmetric Carbamoyl Anion Additions to Chiral N-Phosphonyl Imines via the GAP Chemistry Process and Stereoselectivity Enrichments.

Seifert Cole W CW Pindi Suresh S Li Guigen G

The Journal of organic chemistry 20141209 1

Carbamoyl anions were found to smoothly react with chiral N-phosphonyl imines in toluene at -78 °C to r.t. using LiHMDS as the base. Group-assisted purification (GAP) has been utilized to give the pure amides without using column chromatography or recrystallization. The asymmetric reaction resulted in chiral N-phosphonyl amino amides with good to excellent yields (71-99%) and good crude diastereoselectivities (dr 84:16-95:5). In this GAP procedure, the crude solids are washed with diethyl ether ...[more]

PMID: 25458404

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