positions 9,10 are well known, reports for the synthesis of anthracenes with different substitution patterns are scarce. Herein we review known and report novel synthetic pathways toward anthrols with substituents at 1,2-, 2,3-, and 2,6- positions. We present two synthetic approaches: (i) building of the anthracene tricyclic fused ring systemfrom the appropriate benzene derivatives, and (ii) reduction
Halophenol Rearrangement in Lewis Acid-Catalyzed Friedel - Crafts Conditions: Evidence of Competitive Initial Protonation and Acylation
作者:Koushik Saha、Nordin H. Lajis、Faridah Abas、Nabil Ali Naji、A. Sazali Hamzah、Khozirah Shaari
DOI:10.1071/ch08084
日期:——
Halogen rearrangement was observed during the Lewis acid-catalyzed Friedel–Crafts reaction of phthalic anhydride with bromophenols or bromoanisole. Further investigation revealed that 2-, 3-, and 4-bromophenols undergo rearrangement into other isomers under these reaction conditions. Product distribution from these reactions suggested that halogen rearrangement takes place during the s-complex intermediate
Excitation of 2-hydroxy-3-(diphenylhydroxymethyl)-anthracene (7) to SI initiates photodehydration, giving the corresponding quinone methide (QM) that was detected by laser flash photolysis (LFP) in 2,2,2-trifluoroethanol (lambda = 580 nm, tau = 690 +/- 10 ns). The QM decays by protonation, giving a cation (lambda = 520 nm, tau = 84 +/- 3 ps), which subsequently reacts with nucleophiles. The rate constants in the reactions with nucleophiles were determined by LFP, whereas the adducts were isolated via preparative photolyses. The photogeneration of QMs in the anthrol series is important for potential use in biological systems since the chromophore absorbs at wavelengths > 400 nm. Antiproliferative investigations conducted with 2-anthrol derivative 7 on three human cancer cell lines showed higher activity for irradiated cells.