Photosolvolysis of 2-Allylated Anilines to 2-Indanols

It is shown that 2-allylated anilines (cf. Schemes 2–4, 7, and 8) on irradiation in protic solvents such as H₂O. MeOH, and EtOH in the presence of H₂SO₄ undergo a novel photosolvolysis reaction to yield specifically trans-2-hydroxy- and trans-2-alkoxy-1-methylindanes. Intermediates are presumably tricyclo4.3.0.0^1,8]nona-2,4-dienes formed in an intramolecular 2s + 2s] cycloaddition reaction (cf. Scheme 7). On the other hand, N,N,N-trimethyl-2-(1′-methylallyl)anilinium salts 18 (Scheme 6) and 2-(3′-butenyl)-N,N-dimethylaniline ( 17 ) lose on irradiation in MeOH or H₂SO₄/MeOH the ammonium group reductively to yield (1-methylallyl)benzene ( 19 ) and 1-methylindane ( 20 ), respectively.