H2O2-Mediated Synthesis of a Quinazolin-4(3H)-one Scaffold: A Sustainable Approach.

A quinazolin-4(3H)-one ring system is a privileged heterocyclic moiety with distinctive biological properties. From this perspective, the development of an efficient strategy for the synthesis of quinazolin-4(3H)-one has always been in demand for the synthetic chemistry community. In this report, we envisaged an efficient protocol for the synthesis of quinazolin-4(3H)-one using substituted 2-amino benzamide with dimethyl sulfoxide (DMSO) as a carbon source and H2O2 as an effective oxidant. Mechanistically, the reaction proceeds through the radical approach with DMSO as one carbon source. To further substantiate the synthetic claim, the synthetic protocol has been extended to the synthesis of the anti-endotoxic active compound 3-(2-carboxyphenyl)-4-(3H)-quinazolinone.

The recent advances in cobalt-catalyzed C(sp3)-H functionalization reactions.

Over the past decades, reactions involving C-H functionalization have become a hot theme in organic transformations because they have a lot of potential for the streamlined synthesis of complex molecules. C(sp3)-H bonds are present in most organic species. Since organic molecules have massive significance in various aspects of life, the exploitation and functionalization of C(sp3)-H bonds hold enormous importance. In recent years, the first-row transition metal-catalyzed direct and selective functionalization of C-H bonds has emerged as a simple and environmentally friendly synthetic method due to its low cost, unique reactivity profiles and easy availability. Therefore, research advancements are being made to conceive catalytic systems that foster direct C(sp3)-H functionalization under benign reaction conditions. Cobalt-based catalysts offer mild and convenient reaction conditions at a reasonable expense compared to conventional 2nd and 3rd-row transition metal catalysts. Consequently, the probing of Co-based catalysts for C(sp3)-H functionalization is one of the hot topics from the outlook of an organic chemist. This review primarily focuses on the literature from 2018 to 2022 and sheds light on the substrate scope, selectivity, benefits and limitations of cobalt catalysts for organic transformations.

The recent advances in K2S2O8-mediated cyclization/coupling reactions via an oxidative transformation.

Transition metal-free organic transformations using K2S2O8 is one of the most efficient methods for the formation of carbon-carbon/carbon-heteroatom bond in organic synthesis. K2S2O8-mediated transformations provide a cost-effective and green method for these type of transformations. In addition, these reaction methods are alternatives for many metal-mediated/catalyzed reactions. This article mainly describes the recent advances in K2S2O8-mediated cyclization/coupling reactions via oxidative transformation in organic synthesis in the last few years.

gem-Diborylalkanes: recent advances in their preparation, transformation and application.

Recently, gem-diborylalkanes have attracted much attention as versatile building blocks and fundamental intermediates in organic synthesis, because they enable multiple C-C bond construction and further transformation at C-B bonds. Importantly, gem-diborylalkanes can be utilised as bisnucleophilic partners in a variety of chemo-selective C-C bond-forming reactions. This review describes recent developments in synthesising gem-diborylalkanes in complex molecules along with their chemical transformation. In the first part of the review the different synthetic approaches used to synthesise gem-diborylalkanes are described. In the second part, an overview of the chemoselective transformation of gem-diborylalkanes into various functionalized materials is discussed along with one-carbon homologation of diborylmethane via a selective uni- and bidirectional method.

Ruthenium-Catalyzed C-H Benzoxylation of tert-Benzamides with Aromatic Acids by Weak Coordination.

A highly regioselective C-H benzoxylation of tertiary benzamides with aromatic acids by weak O-amide coordination in the presence of [{RuCl2(p-cymene)}2], AgSbF6, and (NH4)2S2O8 in 1,2-dichloroethane at 100 °C for 24 h to afford ortho-benzoxylated tertiary benzamides is described. Selectively, ortho-benzoxylated cyclic benzamides were converted into ortho-benzoxylated benzaldehydes by using Cp2ZrHCl at room temperature. Subsequently, substituted salicylic acids were prepared by deprotection of the ester and amide groups of ortho-benzoxylated cyclic benzamides.

Ruthenium-catalyzed highly regio- and stereoselective hydroarylation of aromatic sulfoxides with alkynes via C-H bond activation.

Chelation-assisted alkenylation at the ortho C-H bond of aromatic sulfoxides with alkynes in the presence of a ruthenium catalyst, AgSbF6 and pivalic acid yielding trisubstituted alkenes in good to excellent yields in a highly regio- and stereoselective manner via a deprotonation metalation pathway is described. Later, ortho-alkenylated aromatic sulfoxides were converted into α-acyloxy-thioether and a 2,3-disubstituted benzothiophene derivative.

ortho-Benzoxylation of N-alkyl benzamides with aromatic acids catalyzed by ruthenium(II) complex.

A highly regioselective ortho-benzoxylation of N-alkyl benzamides with aromatic acids in the presence of [{RuCl2(p-cymene)}2], AgSbF6 , and (NH4)2S2O8 in 1,2-dichloroethane at 100 °C for 24 h affording ortho-benzoxylated N-alkyl benzamides by C-H bond activation is described. Further, Ru-catalyzed alkenylation is done at the ortho C-H bond of benzoxylated N-alkyl benzamides with alkenes in water solvent. Subsequently, the benzoxyl moiety of N-alkyl benzamides was converted into a hydroxyl group in the presence of base or acid. A possible reaction mechanism was proposed to account for the present coupling reaction.

Ruthenium-catalyzed oxidative ortho-benzoxylation of acetanilides with aromatic acids.

Substituted acetanilides reacted with aromatic acids in the presence of [{RuCl2(p-cymene)}2], AgSbF6 and (NH4)2S2O8 in ClCH2CH2Cl at 100 °C for 24 h yielding ortho-benzoxylated acetanilides in good to excellent yields in a highly regioselective manner via C-H bond activation.

Ruthenium-catalyzed regioselective oxidative coupling of aromatic and heteroaromatic esters with alkenes under an open atmosphere.

A ruthenium-catalyzed oxidative coupling of substituted aromatic and heteroaromatic esters with alkenes in the presence of catalytic amounts of AgSbF(6) and Cu(OAc)(2) to provide highly substituted alkene derivatives in good to excellent yields under an open atmosphere is described.

Highly regio- and stereoselective ruthenium(II)-catalyzed direct ortho-alkenylation of aromatic and heteroaromatic aldehydes with activated alkenes under open atmosphere.

Various aromatic and heteroaromatic aldehydes reacted with activated alkenes in the presence of a catalytic amount of [{RuCl(2)(p-cymene)}(2)], AgSbF(6), and Cu(OAc)(2)·H(2)O to give substituted alkene derivatives in a highly regio- and stereoselective manner. The corresponding alkene derivatives were further converted into unusual four-membered cyclic ketones or a polycyclic isochromanone derivative via a photochemical rearrangement. Notably, the catalytic reaction was conducted under an open atmosphere.

Ruthenium-catalyzed ortho-alkenylation of aromatic ketones with alkenes by C-H bond activation.

A ruthenium-catalyzed chelation-assisted C-H bond activation of aromatic ketones and the reaction with olefins to provide Heck-type products in good to excellent yields with a high regio- and stereoselective manner is described.