Metallation of pyridines and quinolines in the presence of a remote carboxylate group. New syntheses of heterocyclic quinones

Abstract

2-(3- and 2-Pyridylcarbonyl)benzoic acids (2,3), 2-(2-pyridylcarbonyl)thiophene-3-carboxylic acid (6), 2-(3-quinolylcarbonyl)benzoic acid (10), and most of the corresponding esters (compounds 1,7 and 9 ) are readily synthesized and involved in a deprotonation-condensation sequence. Biologically active aza-anthraquinones such as benzo[g]isoquinoline-5,10-dione (2-azaanthraquinone, 4 ) and benzo[g]quinoline-5,10-dione (1-azaanthraquinone, 5) are prepared using the strategy. Extension to other heterocyclic quinones such as thieno[3,2-g]quinoline-4,9-dione (8) and benzo[j]phenanthridine-7,12-dione (11) is also investigated.

A Survey of Synthetic Routes towards the Pyranonaphthoquinone Antibiotic Pentalongin and Syntheses of the Corresponding Nitrogen Derivatives

“…[88][89][90][91] A better strategy constitutes the synthesis of substituted benzoylated pyridines 118 or 119 and subsequent ring closure. The synthesis of pyridines 118 and 119 can be performed via initial lithiation of pyridines and subsequent reaction with suitable arenes, 90,92,93 or alternatively via lithiated arenes which can react with isonicotinic esters 94 or activated pyridines. 95 Analogous condensations were performed less efficiently via a radical benzoylation of pyridine-3-carbonitriles.…”

“…To date, three major synthetic pathways have been developed (Scheme 20): (i) via cycloaddition reactions of suitable dienes to isoquinoline-5,8-dione or naphthoquinone derivatives 115 and 116 [81][82][83][84][85][86][87] (ii) via initial acylation of pyridines or substituted arenes followed by an intramolecular condensation/cyclization of intermediates 118 or 119 [88][89][90][91][92][93][94][95][96][97] and (iii) via construction of the heterocyclic ring starting from substituted naphthoquinones 120 or 121 [cf. the biomimetic construction of bostrycoidin starting from fusarubin (96)].…”

Synthesis of Tetrahydrobenzo[g]Quinoline Derivatives Using Recoverable Carbonaceous Material as Heterogeneous Catalyst

“…Thus, developing an efficient approach to the synthesis of these azaheterocycles is of significance. Recently, many synthetic methods for tetrahydrobenzo[ g ]quinoline derivatives have been reported . However, these methods usually suffer from one or more disadvantages, such as use of expensive substrates, poor chemoselectivity, limited tolerance of functional groups, and unreusability of the catalysts.…”

Platinum-Catalyzed Assembly of Quinaldine from Aniline and Ethylene

“…The synthesis of quinoline derivatives is the subject of intense research because of the presence of the quinoline scaffold in a number of biologically active compounds such as antimalaria, anti-inflammatory, antiasthmatic, antibacterial, antihypertensive and tyrosine kinase inhibiting agents . In addition, quinoline molecules, metal complexes and polymers are being investigated as materials for electronic and optoelectronic applications. − The simplest quinoline derivative is 2-methylquinoline, or quinaldine.…”