反应详情

Mannosides were synthesized by traditional Lewis acid mediated glycosylation of mannose penta-acetate by reaction with 2-substituted 4-bromophenols using BF3 etherate (Scheme 1). Suzuki cross-coupling with commercially available 3-substituted phenyl boronic acid derivatives gave protected ortho-substituted 4′-biphenyl mannosides in excellent yields and subsequent deprotection with NaOMe gave mannosides 4-5. 6 was prepared following the procedure previously described. Synthesis of di-amides 7-8 followed a similar procedure but required the synthesis of 3,5-di-(N-methyl aminocarbonyl)phenyl boronic acid pinacol ester 9. Shown in Scheme 1, amidation of dimethyl 5-bromoisophthalate by reaction of methylamine in ethanol proceeded in quantitative yield to give N,N-dimethyl 5-bromoisophthalamide. Installation of the boronate ester was accomplished by Pd-mediated coupling with bis(pinacolato)diboron to give 9. Suzuki coupling and deprotection as before yielded compounds 7-8.

1. custom6 was prepared