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The oxidative [3+2+1] annulation reaction of aldehydes, 5‐aminopyrazoles, and nitriles is achieved under the oxidation of I2/O2, affording various valuable pyrazolo[3,4‐d]pyrimidines in 27%–91% yields. The salient feature of this reaction is transition‐metal free, operationally simple, broad substrate scope, good functional group tolerance, and gram‐scalable. Remarkably, the corresponding products exhibited intriguing photophysical properties such as Aggregation‐Induced Emission (AIE) and intramolecular charge transfer (ICT) and showed good potential to specifically light up lipid droplets (LDs) in living cells with bright fluorescence, low cytotoxicity, and good photostability. [ABSTRACT FROM AUTHOR]

A regioselective Rh(III)-catalyzed C–H bond naphthylation and cascade directing group (DG) transformation has been realized with aryl imidates and oxa bicyclic alkenes. Diverse naphthalene-substituted aromatic esters were synthesized fruitfully. The DG transformation into ester endows the strategy with chances of further C–H bond functionalization and derivatization. Preliminary mechanistic studies demonstrate that the ester carbonyl oxygen possibly originates from the corresponding oxa bicyclic alkene. [ABSTRACT FROM AUTHOR]

Efficient oxidative [3 + 2] annulation reaction involving aryl hydrazones and heterobicyclic alkenes has been realized with inexpensive and earth-abundant cobalt salts under aerobic conditions. The reaction proceeds via directing-group-assisted C–H activation and exo-selective migratory insertion, followed by the intramolecular nucleophilic attack of the alkylcobalt(III) species onto the imine with high anti-diastereoselectivity to provide complex indane derivatives. The generation of three contiguous stereogenic centers within the indanyl unit and the avoidance of the use of stoichiometric amounts of metal oxidants make this transformation more valuable and appealing. [ABSTRACT FROM AUTHOR]

Rhodium(III)‐catalyzed dehydrogenative annulation of 2‐aryl‐imidazo[1,2‐a]pyridines with maleimides is described. The reaction afforded 1H‐benzo[e]pyrido[1′,2′:1,2]imidazo[4,5‐g]isoindole‐1,3(2H)‐diones in high yields with wide range of functional group tolerance. The reaction proceeds through Rh(III)‐catalyzed C−H bond activation, followed by maleimide insertion and intramolecular cyclization. Photophysical properties of 1H‐benzo[e]pyrido[1′,2′:1,2]imidazo[4,5‐g]isoindole‐1,3(2H)‐diones were studied with UV‐visible and fluorescence spectroscopy and validated by quantum chemical calculations. All the annulated products showed large Stokes shift values with emission in the range of 530–618 nm, and moderate to high quantum yields. [ABSTRACT FROM AUTHOR]

Synthesis of naphthol‐indoles starting from easily available 1,3‐diynes and sulfoxonium ylides via RhIII‐catalyzed C−H activation/hydroamination cascade process in a one pot manner has been developed. The reaction proceeds through a RhIII‐catalyzed arene ortho C−H activation and silver‐catalyzed hydroamination cascade to afford a variety of C2 position functionalized indoles in good yields with broad substrate scope and good functional group tolerance. [ABSTRACT FROM AUTHOR]

Twofold C−H annulation of readily available formamides and alkynes without built‐in chelating groups was achieved. Ni−Al bimetallic catalysis enabled by a bulky BINOL‐derived chiral secondary phosphine oxide (SPO) ligand proved to be critical for high reactivity and high selectivity. This reaction uses readily available formamides as starting materials and provides a concise synthetic pathway to a broad range of chiral ferrocenes in 40–98 % yield and 93–99 % ee. [ABSTRACT FROM AUTHOR]

Twofold C−H annulation of readily available formamides and alkynes without built‐in chelating groups was achieved. Ni−Al bimetallic catalysis enabled by a bulky BINOL‐derived chiral secondary phosphine oxide (SPO) ligand proved to be critical for high reactivity and high selectivity. This reaction uses readily available formamides as starting materials and provides a concise synthetic pathway to a broad range of chiral ferrocenes in 40–98 % yield and 93–99 % ee. [ABSTRACT FROM AUTHOR]

A library of novel bis-spiropiperidone-tetrahydrothiophene hybrid heterocycles have been synthesized via pseudo-three-component domino reaction of (3E,5E)-3,5-bis(arylidene)-1-methyl/benzyl piperidin-4-ones and 1,4-dithiane-2,5-diol in the presence of triethylamine. This transformation presumably proceeds via two annulations each involving the generation of 2-mercaptoacetaldehyde from 1,4-dithiane-2,5-diol-Michael addition-intramolecular aldol sequence which result in the creation of four new bonds in a one-pot operation. The advantages of this protocol are high atom economy, high stereoselectivity, short reaction time, and operational simplicity. [ABSTRACT FROM AUTHOR]