Synthesis of potential antimalarial agents. Preparation of some 6-amino-5,8-dimethoxyquinolines and the corresponding 6-amino-5,8-quinolinediones

Reduction of organic compounds with diborane

“…An interesting application of this reduction involves the conversion of the 5,8-quinolinedione 61 to the 5,8-dihydroxyquinoline 62 in an 86% isolated yield (eq 109). 214 Anthraquinone reacts extremely slowly with BH3-THF showing only one hydride uptake after 7 days without hydrogen NaBH4; C, B2H6 in diglyme; D, A plus a large excess of BF3; E, BH3-THF plus excess BF3; F, BH3-THF then heating at reflux; G, BH3-THF at 0-25 °C: H, G plus added ethyl acetate to inhibit reduction of ester. "The carbonyl marked with an asterisk Is converted to -CH3-to give the product.…”

An efficient method for the synthesis of 6,7-bis(alkylthio- or alkylamino-substituted)quinoline-5,8-diones via nucleophilic addition/oxidation of alkylthio and alkylamino derivatives to quinoline-5,8-dione

“…Quinolinequinones have shown promise in possible anti-tumor, [1][2][3][4] anti-cancer, 5 anti-bacterial, 6 trypanocidal, 7 anti-tuberculosis, 8 anti-inflammatory, 9 anti-malarial agents, 10 and anti-fungal. 11 Scheme 1.…”