2a-Substituted dichlorodihydrocyclobuta[c]quinolin-3(4H)-one (3) and trichlorovinyl-2-quinolone (4) were obtained from the cross photocycloadduct of 2-quinolone and tetrachloroethylene. The position of the substituent on 3 was determined from the NOE volumes in the NOESY spectrum in comparison with the AM1 geometries. The reaction of the photoadduct (1) with a base or nucleophile, yielding 3 and/or 4, was interpreted to proceed via a cyclobutene intermediate formation followed by an SN2′ displacement or [2+2] cycloreversion.
从2-
喹诺酮和
四氯乙烯的交叉光环加合物中得到了2a-取代的二
氯二氢环丁[c]
喹啉-3(4H)-酮(3)和
三氯乙烯基-2-
喹诺酮(4)。通过与
AM1几何形状的比较,从NOESY谱中的NOE体积确定了3上取代基的位置。光加合物(1)与碱或亲核试剂反应生成3和/或4的过程被解释为通过
环丁烯中间体的形成,随后发生SN2′取代或[2+2]环反转变。