Grupo de Lactamas y Heterociclos Bioactivos, Departamento de Química Orgánica I, Unidad Asociada al CSIC, Facultad de Química, Universidad Complutense de Madrid, 28040 Madrid, Spain.
J Org Chem. 2013 Jul 5;78(13):6688-701. doi: 10.1021/jo401013d. Epub 2013 Jun 18.
The preparation of previously unknown (indol-3-yl)-α-allenols and -allenones was accomplished from indole-3-carbaldehydes, through indium-mediated Barbier allenylation reaction taking advantage of the N-(2-pyridyl)sulfonyl group. Metal-catalyzed cyclizations of oxyallenyl C3-linked indoles proceeded in two ways depending on the presence or absence of the N-(2-pyridyl)sulfonyl group. For allenols, gold-catalyzed oxycyclization occurred in the presence of the protecting group; in the absence of the protecting group, palladium- and gold-catalyzed benzannulations operated. On the contrary, under gold catalysis furyl-indoles were obtained as exclusive products from NH-allenones, while 5-endo carbocyclization adducts were the major components starting from N-SO2py-protected allenones. These cyclization reactions have been developed experimentally, and their mechanisms have additionally been investigated by a computational study.
先前未知的（吲哚-3-基）-α-烯丙醇和 -烯酮的制备是从吲哚-3-甲醛醛出发，通过铟介导的 Barbier 烯丙基化反应，利用 N-(2-吡啶基)磺酰基基团。根据是否存在 N-(2-吡啶基)磺酰基基团，oxyallenyl C3 连接的吲哚的金属催化环化以两种方式进行。对于烯丙醇，在存在保护基团的情况下进行金催化的氧环化；在没有保护基团的情况下，钯和金催化的苯并环化起作用。相反，在金催化下，从 NH-烯酮中获得呋喃吲哚作为唯一产物，而从 N-SO2py 保护的烯酮开始，5-endo 碳环化加合物是主要成分。这些环化反应已经通过实验进行了开发，并通过计算研究进一步研究了它们的机制。
