Selective methylphosphonylation of an echinocandin B analog derived from LY303366

Abstract Echinocandin B (ECB) analog 1c was methylphosphonylated with the new reagent dimethyldiphosphonate 7 . Selective functionalization of the phenol group was achieved in the presence of 11 other reactive alcohol and amide groups. The phosphonylation was best conducted in a mixture of THF and DMF using lithium t -butoxide as base. Methylphosphonate diester 1d was deprotected by hydrogenolysis to afford methylphosphonate monoester 1e , a potential prodrug for ECB analog 1c .