Palladium-Catalyzed Bicyclization of 2-Bromo-1,6-dienes and -1,6-enynes to 5-Membered-Ring-Annelated Vinylcyclopropane Derivatives
作者:Arno G. Steinig、Armin de Meijere
DOI:10.1002/(sici)1099-0690(199906)1999:6<1333::aid-ejoc1333>3.0.co;2-g
日期:1999.6
can be regarded as a dehydrodimer of the vinylcyclopropane 35. The presumption that the formation of 63 involves the alkenylpalladium species 65 was supported by its successful inter- as well as intramolecular trapping with formate as a hydride source to yield the vinylcyclopropane 35. The reaction pathways leading to the vinylcyclopropane derivatives 35 and 63 have in common that an alkylpalladium species
钯催化的 2-溴-1,6-二烯 6 与溴烯基部分上的乙酰氧基甲基取代基的环化不仅产生预期的 1-乙酰氧基甲基-1,3-二烯 40,而且产生双环乙烯基环丙烷 35, 1,3-二烯 36 和三烯 37(树枝状烯)。所有这些化合物均由 2-溴-1,6-二烯的初始 5-exo-trig 环化产生。By proper choice of the reaction conditions (ligand, base, allylic leaving group) each of these compounds could be formed selectively. 少量 (3–5%) 的异构化 1-乙酰氧基甲基-1,3-二烯 38 和 6-内产物 39 也被分离出来。由于烯基部分(化合物27)上的乙酰氧基甲基取代基,仅形成1,4-二烯44。在三键上具有甲氧基羰基氧基亚甲基取代基的相关 1,6-烯炔 57