orthoformate and amines. Ethyl N‐(4‐methoxyphenyl)formimidate and N,N′‐bis(4‐methoxyphenyl)formamidine could also be used as the ring closing reagent. The Mannich bases 13 and 14 were produced in a reaction of 9 with formaldehyde and piperidine. The ribosides 15 were obtained by melting a mixture of 9 and 1,2,3,5‐tetra‐O‐acetyl‐β‐D‐ribofuranose in the presence of p‐toluenesulphonic acid.
1,5-二氢-4H-
吡唑并[3,4-d]
嘧啶-4-酮5和6通过相应的5-
氨基
吡唑-4-羧酸乙酯与
原甲酸三乙酯和胺反应制备。N-(4-
甲氧基苯基)甲
酰亚胺乙酯和N,N'-双(4-
甲氧基苯基)
甲脒也可用作闭环试剂。曼尼希碱 13 和 14 是在 9 与
甲醛和
哌啶的反应中产生的。
核糖 15 是通过在
对甲苯磺酸存在下熔化 9 和 1,2,3,5-四-O-乙酰-β-D-
呋喃核糖的混合物而获得的。