Trichloroacetamides obtained via Overman [3,3] sigmatropic rearrangement were converted into dibenzyl guanidines. The key step was conversion of carbodiimide intermediate into guanidine by scandium or ytterbium trifluoromethane-sulfonates. This method was applied to a synthesis of guanidinium ring of (−)-tetrodotoxin.
通过 Overman [3,3] sigmatropic 重排获得的三
氯乙酰胺被转化为二苄基
胍。关键步骤是通过
三氟甲烷磺酸钪或
镱将碳二
亚胺中间体转化为
胍。这种方法被应用于合成 (-)-
河豚毒素的
胍环。