Nanosized particles of organically modified silica as microreactors to enhance the regioselectivity in the photocycloaddition of 9-substituted anthracenes.
[reaction: see text] Nanosized particles of modified silica with 3-ammoniumpropyl residue have been prepared and successfully used as microreactors to control the regioselectivity of the photocycloaddition of five 9-substituted anthracences [AnCH(2)N(+)(CH(3))(3)Br(-) (1), AnCH(2)COO(-)Na(+) (2), AnCH(2)CH(2)COOH (3), AnCH(2)OH (4), AnCH(3) (5), where An = 9-anthryl]. While the photocycloaddition of the five substrates in methanol mainly gave rise to their head-to-tail (h-t) photocyclomers, irradiation of 1-4 incorporated in the suspension of the modified silica in methanol almost exclusively yielded the head-to-head (h-h) photocyclomers with high quantum yields.
Wu
Da-Yong
DY
Technical Institute of Physics and Chemistry, The Chinese Academy of Sciences, Beijing 100101, China.
Chen
Bin
B
Fu
Xiao-Gang
XG
Wu
Li-Zhu
LZ
Zhang
Li-Ping
LP
Tung
Chen-Ho
CH