Synthesis of (2S,4R,5R)-4,5,6-Trihydroxynorleucine and 5-Hydroxynorvaline from precursors obtained by an unusual rearrangement in a 5,6-dihydro-2-pyrone
作者:Alejandro P. Nin、Rosa M. de Lederkremer、Oscar Varela
DOI:10.1016/0040-4020(96)00767-3
日期:1996.9
6-O-benzylidene-2,3-dideoxy-d-erythro-hex-2-enono-1,5-lactone (2), readily prepared from d-glucosamine, undergoes a rearrangement on treatment with tin(IV) chloride which leads to 3-acetamido-2-pyrone (3) and 2-acetamido-2,3-dideoxy-4,6-O-formylidene-d-threo-hex-2-enono-1,5-lactone (4). A mechanism is proposed for this unusual rearrangement, which was not observed for other analogous hex-2-enono-1,5-lactones. For
由乙酰氨基葡萄糖容易制得的2-乙酰氨基-4,6- O-亚苄基-2,3-二脱氧-二赤-己二-2-enono-1,5-内酯(2)在用氯化锡(IV)生成3-乙酰氨基-2-吡喃酮(3)和2-乙酰氨基-2,3-二脱氧-4,6- O-甲叉基-d-苏-己二-2-烯诺-1,5 -内酯(4)。对于这种异常重排,提出了一种机制,其他类似的十六烷基-2-烯醇-1,5-内酯未发现这种机制。例如,2(2-乙酰氧基-4,6- O-亚苄基-3-脱氧-二赤藓基-hex-2-enono-1,5-内酯的2-乙酰氧基类似物7合成)并用氯化锡(IV)处理,得到3-乙酰氧基-6-氯甲基-2-吡喃酮(8)作为主要产物。2-吡喃酮衍生物3和4是分别用于合成5-羟基正缬氨酸(12)和(2 S,4 R,5 R,)-4,5,6-三羟基正亮氨酸(14)的方便的前体。后者通过4的非对映选择性氢化,然后脱保护而制备。