Efficient synthesis of quinazolines by the iron-catalyzed acceptorless dehydrogenative coupling of (2-aminophenyl)methanols and benzamides

Arene Ruthenium(II)-Catalyzed Sustainable Synthesis of 2,4-Disubstituted Quinazolines via Acceptorless Dual Dehydrogenative Coupling of Alcohols

We demonstrate an efficient and sustainable strategy for the direct synthesis of 2,4-disubstituted quinazolines by arene Ru(II)benzhydrazone complex via the eco-friendly sequential acceptorless dehydrogenative coupling of 2-aminobenzhydrol derivatives and benzyl alcohols for the first time. The new ruthenium(II) complex of the general formula [(η6-p-cymene)Ru(L1)Cl] (L1-acenaphthenequinone hydrazone) has been synthesized and characterized by analytical, spectroscopic, and single-crystal X-ray diffraction techniques. A broad spectrum of 2,4-disubstituted quinazolines have been successfully derived (25 examples) from 2-aminobenzhydrol derivatives with various benzyl alcohols using 1 mol % of catalyst loading in the presence of NH4OAc. The present protocol is highly selective and produces a maximum yield of 95% under mild reaction conditions. The different reaction intermediates detected through control experiments such as aldehyde, 2-aminobenzophenone, benzylidene(amino)phenylmethanone, and 1,2-dihydroquinazoline are isolated and authenticated by the NMR study. Gratifyingly, the coupling reaction is a simple and atom economic with the release of water and hydrogen gas as the only byproducts. A gram-scale synthesis of 2-(4-methoxyphenyl)-4-phenylquinazoline illustrates the synthetic utility of the present protocol.

Visible Light-Induced Decomposition of Acyl Peroxides Using Isocyanides: Synthesis of Heteroarenes by Radical Cascade Cyclization

Visible light-mediated facile synthesis of heteroarenes, namely, isoquinolines, benzothiazoles, and quinazolines, is demonstrated by employing isocyanides and inexpensive acyl peroxides. It is shown for the first time that singlet-excited isocyanides decompose acyl peroxides into aryl/alkyl radicals. The latter attack isocyanides, yielding imidoyl radicals that subsequently cyclize to afford heteroarene products. The protocol involving radical cascade reactions obviates the requirement of any external photocatalyst, oxidant, additive, and base.

Transition-metal-catalyzed synthesis of quinazolines: A review

Quinazolines are a class of nitrogen-containing heterocyclic compounds with broad-spectrum of pharmacological activities. Transition-metal-catalyzed reactions have emerged as reliable and indispensable tools for the synthesis of pharmaceuticals. These reactions provide new entries into pharmaceutical ingredients of continuously increasing complexity, and catalysis with these metals has streamlined the synthesis of several marketed drugs. The last few decades have witnessed a tremendous outburst of transition-metal-catalyzed reactions for the construction of quinazoline scaffolds. In this review, the progress achieved in the synthesis of quinazolines under transition metal-catalyzed conditions are summarized and reports from 2010 to date are covered. This is presented along with the mechanistic insights of each representative methodology. The advantages, limitations, and future perspectives of synthesis of quinazolines through such reactions are also discussed.

Iridium-Catalyzed Acceptorless Dehydrogenative Coupling of 2-Aminoarylmethanols with Amides or Nitriles to Synthesize Quinazolines

An efficient iridium-catalyzed acceptorless dehydrogenative coupling (ADC) reaction for the preparation of various quinazolines from 2-aminoarylmethanols and amides or nitriles had been developed. A wide range of substituted 2-aminobenzyl alcohols and (hetero)aryl or alkyl benzamides and nitriles were well compatible to afford various quinazolines in excellent yields. Merits of this new strategy are the high atom-economy, mild reaction conditions, and simple operation, and the methodology is suitable for a variety of substrates.

Cucurbit[6]uril supported β-Ni(OH)2 nanoparticles as a heterogeneous catalyst for the synthesis of quinazolines via acceptorless dehydrogenative coupling of alcohols with nitriles

Synthesis of a series of quinazolines using β-Ni(OH)2-CB[6] as a heterogeneous nanocatalyst.