The organic ligand of the cofactor of the oxomolybdoenzymes has been synthesised in the protected and masked form, 5. The key steps in the conversion of the previously prepared 3, a protected 5-(2-amino-4-oxopteridin-6-yl)-4-(1,2-dihydroxyethyl)-1,3-dithiol-2-one were: formation of the pyran ring by reaction with a chloroformate giving a protected 8-amino-4-hydroxymethyl-6-(alkyloxycarbonyl)-5a,6,9,10-tetrahydro-[1,3]dithiolo[4′,5′:4,5]pyrano[3,2-g]pteridine-2,10-dione, 10, cyanoborohydride reduction of the 11,11a-imine, protection at N-11, and finally conversion of the alcohol into a protected phosphate giving 5.
氧化
多糖酶辅助因子的有机
配体 5 已被合成为受保护的掩蔽形式。之前制备的 3 是一种受保护的 5-(2-
氨基-4-氧代蝶啶-6-基)-4-(1,2-二羟乙基)-1,3-二
硫环戊-2-酮,其转化的关键步骤是:通过与
氯甲酸酯反应形成
吡喃环,得到受保护的 8-
氨基-4-羟甲基-6-(烷氧羰基)-5a,6,9,10-四氢-[1,3]二
硫环戊并[4′,5′:4,5]
吡喃并[3,2-g]蝶啶-2,10-二酮 10,
氰硼氢化还原 11,11a-
亚胺,在 N-11 处进行保护,最后将醇转化为受保护的
磷酸酯,得到 5。