Aromatic hydrocarbons and heterocycles photocycloaddition

Benzene in the Si (n,n ) excited state is no longer aromatic and is capable of undergoing various chemical reactions not observed in the ground state. Three basic types of photocycloaddition reaction of an alkene to the excited benzene can be de-scribed 802,804,809 816 (a) bicyclo[4.2.0]octa-2,4-dienes (e.g. 191) are formed by ortho-photocycloaddition (1,2- or [2 + 2] photocycloaddition), (b) tricyclo[3.3.0.02 8]oct-3-enes (e.g. 192) are obtained by mcia-photocycloaddition (1,3- or [3 + 2] 

The (photo)chemical and physical properties of fullerenes, spherical carbon molecules, are an important topic in current research, especially in nanotechnology. The molecule with 60 carbons, C(,o. having properties of an electron-deficient alkene, undergoes for example [2 + 2] photocycloaddition similar to aromatic moieties. The absorption spectrum of C l0 exhibits three principal maxima (/max = 211, 256, 328 nm) and a weak band at /. 540nm.xl3 Very weak fluorescence from the lowest excited 

Special Topic 6.10 Cyclopropyl group as a mechanistic probe 

Case Study 6.14 Synthesis of cage compounds - octahedrane 

---