作者:Cuixiang Sun、Xichen Lin、Steven M. Weinreb
DOI:10.1021/jo060084f
日期:2006.4.1
In work directed toward a total synthesis of chartelline A (1a), a strategy was investigated to construct the 10-membered ring of this marine alkaloid via an intramolecular aldehyde/β-lactam cyclocondensation to form the macrocyclic enamide functionality. Therefore, spiro-β-lactam and imidazole fragments were first prepared. Tribromooxindole β-lactam 24 was synthesized from commercially available 5-nitroisatin
在针对沙特琳碱A(1a)的全合成的工作中,研究了一种策略,该方法通过分子内醛/β-内酰胺环缩合以形成大环烯酰胺官能团来构建该海洋生物碱的10元环。因此,首先制备了螺-β-内酰胺和咪唑片段。Tribromooxindoleβ-内酰胺24是通过Staudinger烯酮-亚胺[2 + 2]-环加成策略,由七个步骤和30%的总收率,由市售的5-硝基芥子素(18)合成的。由易得的咪唑酯25有效地制备了带有末端炔基和被掩盖的醛的必要的2-溴咪唑亚基40分十步走。与这两个先进中间体可用时,除了由2-溴咪唑亚基生成的乙炔化锂的40至的γ内酰胺羰基Ñ -Boc-tribromooxindole 24进行了研究,从而得到所需Ñ -Boc缩醛胺41。水解41的丙酮化物部分,然后氧化裂解所得的二醇,得到醛42。不幸的是,用对甲苯磺酸处理醛42不能得到所需的10元大环(Z)-酰胺46,而是高度不饱和的七元环化合物44。