A radical fragmentation/cyclization sequence of a [2+2] photoadduct derivative leads to the formation of the aromadendrane ring system. The 5,7 fused rings of this sesquiterpenoid family are formed in the fragmentation step and the cyclopropane moiety is the result of a 3-exo-trig cyclization. The cyclization step is facilitated by the use of SmI2 as the electron donor and by an ester group to stabilize
[2 + 2]光加合物衍
生物的自由基断裂/环化序列导致形成芳香
芳烃环系统。该
倍半萜类家族的5,7个稠合环在断裂步骤中形成,并且
环丙烷部分是3-外-trig环化的结果。通过使用SmI 2作为电子给体,并通过酯基来稳定所得的应变中间体,可以促进环化步骤。