On the stereoselectivity of iodocarbene and -carbenoid additions to cyclic alkenes
摘要:
Exclusive formation of endo adducts 3d-f, 9, 10, 11 is observed in both carbene and carbenoid CHI additions with eight to twelve membered-ring alkenes. Cyclopentene, in contrast, gives exo compound 4a as only isolable product, whereas cyclohexene and cycloheptene yield both types of product. :CHBr (from HCBr3 and NaN(SiMe3)2) exhibits similar although less pronounced trends: only cyclodecene and cyclododecene lead to pure endo adducts 7e,f.