Three-component Staudinger-type stereoselective synthesis of C-glycosyl-beta-lactams and their use as precursors for C-glycosyl isoserines and dipeptides. A polymer-assisted solution-phase approach

A collection of 4-(C-galactosyl)- and 4-(C-ribosyl)-β-lactams featuring different substituents at C-3 and N-1 was prepared by combining in a one-pot procedure a formyl C-glycoside, a primary amine, and a substituted acetyl chloride in the presence of base (Staudinger-type reaction). Sulfonyl chloride and aminomethylated resins were used in sequence to remove excess of components and by-products. Two pure C-glycosyl-β-lactams were effectively transformed into C-glycosyl-N-Boc-β-amino-α-hydroxy esters (C-glycosyl isoserines) and a C-ribosyl dipeptide via base-promoted heterocycle ring opening by methanol and L-phenylalanine methyl ester, respectively.