<i>p</i>-TSA catalyzed tandem conjugate addition/annulation/elimination process for the synthesis of 2,4-disubstituted-4<i>H</i>-benzo[<i>f</i>]chromenes

983-988A simple and user friendly protocol for the synthesis of biologically important 2,4-diaryl-4H-benzo[f]chromenes has been described starting from the readily available naphthols and chalcones catalyzed by p-TSA

A facile method for the synthesis of various 3-substituted indoles <i style="mso-bidi-font-style:normal">via</i> Michael addition reaction using NbCl₅^§

240-244A mild and efficient method for the synthesis of various 3-substituted indoles is described via a Michael addition reaction using NbCl5 as a Lewis acid catalyst. Simple reaction conditions, short reaction times, less amount of catalyst loading, high yields and substrate diversity are the advantages of this methodology

Alkaline earth metal catalyzed, one-pot, multi-component approach for the synthesis of dihydropyridine, acridine and xanthene derivatives in water

1321-1326Ca(II) catalyzed one-pot multicomponent approach for the biologically important diverse heterocyclic compounds such as hexahydroxanthene diones, dihydropyridines and octahydroacridine diones has been described in water. Use of environ-mentally benign catalyst, water as the green solvent, high yields and substrate diversity are the highlights of the current method

Amine-Triggered Highly Facile Oxidative Benzannulation Reaction for the Synthesis of Anthranilates under Solvent-Free Calcium(II) Catalysis

An amine-triggered facile synthetic approach of anthranilates has been described through benzannulation of readily available chemicals under one-pot solvent-free conditions using Ca­(OTf)₂ as the sustainable catalyst. In this regioselective approach, we described a reasonably longer cascade, which proceeds through β-enamino ester formation/Michael addition/intramolecular aldol reaction/elimination/aromatization/oxidative debenzylation/lactonization with a broad substrate scope and high yields. The isolation of intermediates authenticated the mechanism, and the synthetic utility of the products was also demonstrated

Tris(pentafluorophenyl)borane catalyzed synthesis of cyanohydrins, cyanohydrin trimethylsilyl ethers and α-amino nitriles

1471-1475Tris(pentafluorophenyl)borane catalyzed synthesis of cyanohydrins and trimethylsilylcyanohydrin ethers from carbonyl compounds and α-amino nitriles from imines (Strecker synthesis) has been reported in the presence of trimethylsilylcyanide. The substrate diversity has been extensively studied; various aldehydes, ketones and imines are participating in the methodology. Simple and mild reaction conditions, low levels of catalyst loading and shorter reaction times and high yields are the highlights of this methodology, also the products formed here are very important building blocks in the several biologically active natural products

Oxidative Cleavage of C_sp³–C_sp² and C_sp³–H Bonds with KO^<i>t</i>Bu: Highly Robust and Practical Synthesis of Diaryl/(het-Ar) Ketones

Herein, we report an efficient and practical approach for synthesizing diaryl(het) ketones from R–CO–CHR–Ar through a simultaneous oxidative cleavage of C–C and C–H bonds using KOtBu. This method enables synthesizing a variety of unsymmetrical and symmetrical (hetero)aryl ketones in excellent yields, which are otherwise difficult to make. Besides, we synthesized natural products using this method

Cu-Catalyzed Oxidative C(sp²)–H Cycloetherification of <i>o</i>‑Alkenyl Arenols for the Preparation of Fused Furans

A practically efficient, copper-catalyzed approach for the synthesis of functionally embellished indeno-naphthofurans is developed from 1-(1H-inden-3-yl)naphthalen-2-ols. This intramolecular cycloetherification proceeds via C(sp2)–H oxygenation (C–H bond breaking and C–O bond forming), which enables the atom-economical synthesis of poly fused furans in high yields with large substrate diversity in the open air

Highly Regioselective Synthesis of Oxindolyl-Pyrroles and Quinolines via a One-Pot, Sequential Meyer–Schuster Rearrangement, Anti-Michael Addition/C_(sp³)–H Functionalization, and Azacyclization

A one-pot, sequential Meyer–Schuster (MS) rearrangement of oxindole-derived propargyl alcohols to the corresponding α,β-unsaturated enones and their anti-Michael addition, followed by intramolecular azacyclization is described in a highly regioselective manner using Ca­(OTf)₂ as the promoter. Further, we described the one-pot MS rearrangement, followed by C_(sp³)–H functionalization of 2-methyl azaarenes at α-carbon of these doubly activated alkenes. Control experiments and computational calculations were performed to propose the reaction mechanism