Asymmetric carbamoyl anion additions to chiral N-phosphonyl imines via the GAP chemistry process and stereoselectivity enrichments

Cole W. Seifert, Suresh Pindi, Guigen Li

Research output: Contribution to journalArticlepeer-review

22 Scopus citations

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 1H 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.

Original languageEnglish
Pages (from-to)447-452
Number of pages6
JournalJournal of Organic Chemistry
Volume80
Issue number1
DOIs
StatePublished - 2015

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