Trimethylsilyl-Substituted Propyne Iminium Salts as Building Blocks in [4+2] Cycloaddition Reactions
作者:Joachim Nikolai、Jens Schlegel、Manfred Regitz、Gerhard Maas
DOI:10.1055/s-2002-20964
日期:——
3-(Trimethylsilyl)propyne iminium salts 6a-c and 2-(trimethylsilyl)ethynyl-1,3-benzothiazolium triflate 12 are suitable dienophiles for Diels-Alder reactions with buta-1,3-dienes, cyclopentadiene, cyclohexa-1,3-diene, and anthracene. Tri-tert-butylazete reacts with propyne iminium salts 6a,b to form Dewarpyridines 15a,b. Thermal isomerization of 15b generates the sterically overcrowded pentasubstituted pyridine 16 which features a boat-shaped pyridine ring with the highest deviation from planarity so far reported.
3-(三甲基甲硅烷基)丙炔亚胺盐 6a-c 和 2-(三甲基甲硅烷基)乙炔基-1,3-苯并噻唑鎓三氟甲磺酸盐 12 是适合与 1,3-丁二烯、环戊二烯、1,3 环己烯进行 Diels-Alder 反应的亲二烯体-二烯和蒽。三叔丁基氮杂苯与丙炔亚胺盐 6a,b 反应形成杜瓦吡啶 15a,b。 15b 的热异构化生成空间过度拥挤的五取代吡啶 16,其具有迄今为止报道的平面度偏差最高的船形吡啶环。