French Jonathan M, Diver Steven T
Department of Chemistry, University at Buffalo, the State University of New York , Buffalo, New York 14260, United States.
J Org Chem. 2014 Jun 20;79(12):5569-85. doi: 10.1021/jo500748e. Epub 2014 May 28.
With cationic gold catalysts, internal alkynes bearing both propargylic acyloxy groups and tosylamide pronucleophiles were found to cyclize to give either five- or six-membered ring nitrogen heterocycles. A wide variety of gold catalysts, counterions, and solvents were examined to elucidate their effect on product distribution. In most cases, the direct 5-endo-dig cyclization was found to be the major pathway leading to good yields of dehydropyrrolidine products. Alkyne substrates bearing additional normal alkyl substituents at the propargylic position gave dehydropiperidines as the major product. This pathway is thought to proceed by way of a 1,2- Rautenstrauch rearrangement to produce a vinyl gold(I) carbene, which undergoes conjugate addition by the nitrogen pronucleophile. Structural and electronic factors were studied in the nitrogen pronucleophile and in the migrating acyloxy group. Each was found to have a minor effect on the product ratio.
使用阳离子金催化剂时，发现同时带有炔丙基酰氧基和对甲苯磺酰胺亲核前体的内炔会环化生成五元或六元环氮杂环。研究了多种金催化剂、抗衡离子和溶剂，以阐明它们对产物分布的影响。在大多数情况下，直接的5-内型-双烯环化被发现是导致脱氢吡咯烷产物高产率的主要途径。在炔丙基位置带有额外普通烷基取代基的炔烃底物以脱氢哌啶作为主要产物。该途径被认为是通过1,2-劳滕施特拉赫重排生成乙烯基金（I）卡宾，然后氮亲核前体进行共轭加成。对氮亲核前体和迁移的酰氧基中的结构和电子因素进行了研究。发现它们对产物比例的影响较小。
