Novel Synthesis of Quinoline-7,8-diol Derivative

Quinoline 7,8-diol derivatives can be expected to form metal complexes, and are the moiety of marine alkaloid,which exhibits strong cytotoxic activity against several human tumor. Our synthesis of 6 commences from L-dopa (1)(Scheme 1). Esterification of 2 with methanol and treatment of the resulting ester 3 with trichloroethoxycarbonyl (Troc)chloride yielded the N-protected amino acid ester 4. Treatment of 4 with acrolein in 1.3 mol/L methanolic HCl for 4 d at room temperature yielded the quinoline derivative 5, which was dissolved in 25% aq. HBr and the resulting solution was heated at reflux for 6 h to afford compound 6.……