Clear cut example of preference for a 6-membered ring radical cyclisation over the homologous 5-membered ring radical cyclisation. The reaction of 5-[bromoalkyl]-5H-dibenzo[a,d]cycloheptenes with Bu3SnH
作者:C. Hada、M.D. Banciu、J.-M. Mattalia、M. Chanon
DOI:10.1016/0040-4039(96)00695-8
日期:1996.5
The radical cyclisation reaction of the 5-[2-bromo-ethyl]-5H-dibenzo[a,d]cycloheptene 4 with Bu3SnH and AIBN led to the cyclised hydrocarbon 5 as major product, whereas the bromo-derivative 8 with Bu3SnH and AIBN gave only the straight chain product 9. An explanation based on the conformational rigidity of dibenzo[a,d]cycloheptene system calculated by AM1 method is proposed.
5- [2-溴-乙基] -5H-二苯并[ a,d ]环庚烯4与Bu 3 SnH和AIBN的自由基环化反应导致环化烃5为主要产物,而溴代衍生物8与Bu 3 SnH和AIBN仅给出了直链产物9。提出了基于AM1法计算的二苯并[ a,d ]环庚烯体系的构象刚度的解释。