Total Synthesis of (−)-7-Epicylindrospermopsin, a Toxic Metabolite of the Freshwater Cyanobacterium <i>Aphanizomenon </i><i>o</i><i>valisporum</i>, and Assignment of Its Absolute Configuration
作者:James D. White、Joshua D. Hansen
DOI:10.1021/jo0486387
日期:2005.3.1
the substituted 1-aza-7-oxobicyclo[2.2.1] heptanes 40 and 41 in a ratio of 2:1, respectively. Reductive N−O bond cleavage of 40 followed by carbonylation gave cyclic urea 47 in which inversion of the secondary alcohol was effected via an oxidation−reduction sequence. After conversion of the p-bromobenzyl ether 50 to azide 54, activation of the cyclic urea as its O-methylisourea and reduction of the
由醛20与羟胺36缩合得到的Z和E硝基38和39进行分子内偶极环加成,分别以2∶1的比例得到取代的1-氮杂-7-氧代双环[2.2.1]庚烷40和41。40的还原性N-O键裂解,然后进行羰基化,得到环状脲47,其中仲醇的转化是通过氧化还原序列进行的。在将对溴苄醚50转化为叠氮化物54之后,活化环脲作为其O-甲基异脲和叠氮化物的还原导致自发环化,得到环精子胃蛋白酶的三环核59。整体脱保护,包括将2,4-二甲氧基嘧啶附肢水解成尿嘧啶,然后对所得二醇60进行单硫酸化,得到的物质与天然(-)-7-表基吲哚过氧化物胃蛋白酶(1)相同。( - ) -的不对称合成7- epicylindrospermopsin定义为7其绝对构小号,8 - [R,10小号,12小号,13 - [R,14小号。