adducts of 4, 5a and 5b were obt in the reaction with perfluorobut-2-yne. The formation of 1,5-dihydropentalene 4 is explained by a double ring expansion sequence involving consecutive carbene-carbene rearrangements with 1,3-carbon and subsequent 1,2-hydrogen shifts, supported by the reaction of double labelled (13C-depleted) 3. From readily available 3 at low temperatures formation and fusion of two
在-40°C下用
甲基锂处理反式-1,2-双(
2,2-二
溴环丙基)
乙烯3时,形成1,5-二
氢戊烯(4)作为主要产物。另外,该反应提供了1-和2-
丙二烯基
环戊二烯(5a)和(5b),以及反式-1,
2,4,6,7-八
碳烯(6),新的C 8 H 8异构体。的狄尔斯-阿德耳加成物4,图5a和图5b中与perfluorobut -2-炔反应是O
BT。1,5-二
氢戊烯的形成4由双环扩展序列解释,该序列涉及具有1,3-
碳的连续卡宾-卡宾重排以及随后的1,2-
氢转移,由双标记(贫13 C)3的反应支持。在一个步骤中,由容易获得的3在低温下形成并形成两个5元环。