Towards stable di-carba analogues of guanofosfocins

Guanofosfocins are strong inhibitors of chitin synthases, but also very prone to hydrolytic cleavage. Two advanced intermediates 15 and 20 for the synthesis of stable di-carba-guanofosfocins were prepared via ester 11. Acylation of the allylic C-glycoside 6 with riburonic acid chloride 10 afforded ester 11 in 79% yield. This ester was converted to 15 in four steps and in 54% yield and to 20 in eight steps and in 20% yield.