Palladium-Catalyzed Cascade Oligocyclizations Involving Competing Elementary Steps Such as Thermal [1,5]-Acyl Shifts
作者:Wajdi M. Tokan、Stefan Schweizer、Claudia Thies、Frank. E. Meyer、Philip J. Parsons、Armin de Meijere
DOI:10.1002/hlca.200900070
日期:2009.9
Palladium(Pd)‐catalyzed oligocyclizations of 2‐bromotetradec‐1‐ene‐7,13‐diynes with an unsubstituted terminal acetylene moiety like 3 and 5 and 15‐bromohexadec‐15‐ene‐3,9‐diyn‐2‐ones like 4 and 6 afforded fulvene derivatives 20 and 21 (Scheme 7) and bis(cyclohexane)‐annulated methylenecyclopentene systems 16 and 18 (Schemes 5 and 6), respectively. These transformations constitute cascades of cyclizing
钯(Pd)催化的2-溴四癸-1-烯-7,13-二炔具有未取代的末端乙炔部分(如3和5)和15-溴十六烷-15-烯-3,9-二炔-2-酮的寡聚化4和6分别提供富烯衍生物20和21(方案7)和双(环己烷)环化的亚甲基环戊烯体系16和18(方案5和6)。这些转变分别构成环化碳环化步骤的级联,并分别产生[1,5]-σH-原子和酰基转移(方案8))。相比之下,在不饱和C,C键(例如1和2)之间具有1个三原子和1个4原子链的类似底物的行为不同,在于Pd取代的hexa-1,3,5-triene中间体12经过6 π -electrocyclization代替5-外型-TRIG carbopalladation随后β -hydride消除到配料三环双-环化苯衍生物13和14(方案4)。