The intramolecular cyclization of carbonyl compounds via γ-hydrogen abstraction is also possible to give four membered cyclic alcohols (Scheme 4). This reaction is facilitated by the presence of a heteroatom at the β-position of the alkyl chain. The side reaction which can give degradation products is known as Norrish type II reaction (Scheme 5).

Scheme 5

Scheme 6

2.5.1.2 Reduction of Aromatic Compounds

The aromatic hydrocarbons such as benzene, biphenyl, naphthalene and anthracene in their excited states react with amine to give reduced or aminated products. The reaction involves the transfer of lone pair electron of amine to the excited state singly occupied molecular orbital of aromatic compound (Scheme 6).
The excited aromatic compounds could also be reduced by hydride source such as sodium borohydride, lithium aluminum hydride of metal hydride (Scheme 7). The reaction may undergo via the following sequences.

Scheme 7