Three-component Staudinger-type Stereoselective Synthesis of C-Glycosyl β-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-(Cribosyl)- b-lactams featuring different substituents at C-3 and N-1 was prepared by combining in a onepot 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-b-lactams were effectively transformed into C-glycosyl-N-Boc-b-amino-a-hydroxy esters (C-glycosyl isoserines) and a C-ribosyl dipeptide via base-promoted heterocycle ring opening by methanol and l-phenylalanine methyl ester, respectively.