Enantioselective deprotonation of the 8-oxabicyclo[3.2.1]octan-3-one: Synthesis of 8-oxa-norcocaines and 8-oxa-pseudonorcocaines
作者:Daniele Simoni、Marinella Roberti、Riccardo Rondanin、Alan P. Kozikowski
DOI:10.1016/s0040-4039(99)00763-7
日期:1999.6
deprotonation of the 8-oxabicyclo[3.2.1]octan-3-one with chiral lithium amides 5 and 6, in the presence of LiCl, gave the chiral lithium enolates which were in turn reacted with methyl cyanoformate. The resulting chiral β-keto esters were reduced with sodium amalgam to afford the 8-oxa-ecgonine- and 8-oxa-pseudoecgonine-like derivatives which allowed facile preparation of the (+)- and (−)-8-oxa-norcocaines
在LiCl存在下,用手性锂酰胺5和6将8-氧杂双环[3.2.1] octan-3-one对映选择性去质子化,得到手性烯醇锂,其随后与氰基甲酸酯反应。将所得的手性β-酮酯用汞齐钠还原,得到8-氧杂-卵子碱和8-氧杂-假芽子碱样衍生物,可以轻松制备(+)-和(-)-8-氧杂-北可卡因和(+)-和(-)-8-氧杂-拟南芥或可卡因。新合成的可卡因的8-氧杂氧化物类似物在84-90%的范围内显示出良好的对映体过量。