TFA-Mediated Synthesis of 1,2,4-Oxadiazoles from Carbamates and Nitriles.

An unprecedented protocol for the synthesis of 1,2,4-oxadiazoles from carbamates has been developed by employing nitriles as both substrates and solvents. This one-pot procedure achieves the formation of C═N bonds via TFA-mediated [3+2] annulation. A series of 1,2,4-oxadiazoles are synthesized in moderate to good yields.

Synthesis of isothiocyanato alkyl sulfides from alkenes using KSCN and DMTSM.

A method for the synthesis of isothiocyanato alkyl sulfides from KSCN and DMTSM under metal-free conditions has been developed. The features of this reaction are low-cost, readily accessible starting materials and the use of KSCN as nucleophiles for C-NCS bond formation. Alkenes with various substituted groups react smoothly and the desired products are obtained in moderate to good yields.

Synthesis of Benzimidazo[2,1-a]isoquinoline and Indolo[2,1-a]isoquinoline Derivatives via Copper-Catalyzed Silylation/Methylation of 2-Arylindoles and 2-Arylbenzimidazoles.

A one-pot method for the synthesis of silylsubstituted/methylsubstituted indolo[2,1-a]isoquinolin-6(5H)-ones and benzimidazo[2,1-a]isoquinoline-6(5H)-ones via copper(II)-initiated silylation/methylation of 2-arylindoles and 2-arylbenzimidazoles was developed. In this procedure, the C-Si bond and C-C bond were constructed by radical addition and cyclization. A series of 2-arylindole and 2-arylbenzimidazole derivatives were facilely transformed to indolo[2,1-a]isoquinolines and benzimidazo[2,1-a]isoquinolines in 39-83% yields.

A catalyst-free method for the synthesis of 1,4,2-dithiazoles from isothiocyanates and hydroxylamine triflic acid salts.

A catalyst-free method for the preparation of 1,4,2-dithiazoles is developed by reactions of isothiocyanates with hydroxylamine triflic acid salts. This reaction achieves C-S, C-N, and S-N bond formation, and a range of products are obtained in moderate to good yields. The obvious feature is using shelf-stable hydroxylamine triflic acid salts as a N source to synthesize heterocycles under mild conditions.

tert-Butyl Nitrite Promoted Oxidative Intermolecular Sulfonamination of Alkynes to Synthesize Substituted Sulfonyl Pyrroles from the Alkynylamines and Sulfinic Acids.

tert-Butyl nitrite promoted oxidative intermolecular sulfonamination of alkynes to synthesize substituted sulfonyl pyrroles from the alkynylamines and sulfinic acids via tandem addition/cyclization was developed. This reaction is performed well by employing tert-butyl nitrite as the oxidant, and various substituted sulfonyl pyrroles are formed in moderate to good yields with no requirement of metal catalysis.

Fe-Catalyzed tandem cyclization for the synthesis of 3-nitrofurans from homopropargylic alcohols and Al(NO3)3·9H2O.

Al(NO3)3·9H2O as a nitro source for the synthesis of 3-nitrofurans from homopropargylic alcohols through Fe-catalyzed tandem cyclization is described. In this transformation, the substituted nitrofurans are obtained through nitration and cyclization. The substrate homopropargylic alcohols with different groups participate smoothly in this process and the desired substituted nitrofurans were obtained in moderate yields.

Copper-Catalyzed Tandem Aerobic Oxidative Cyclization for the Synthesis of Polysubstituted Quinolines via C(sp3)/C(sp2)-H Bond Functionalization.

One-pot Cu-catalyzed tandem aerobic oxidative cyclization for the synthesis of quinolines from 2-vinylanilines/2-arylanilines and 2-methylquinolines via C(sp3)-H/C(sp2)-H bond functionalization has been developed. Dioxygen as an ideal oxidant has been employed for this transformation. The substrates bearing various functional groups perform well in this process and generate the desired products in moderate to good yields.

A method for accessing sulfanylfurans from homopropargylic alcohols and sulfonyl hydrazides.

A sulfenylation/cyclization reaction has been developed for the synthesis of sulfanylfurans in the presence of iodine. These processes provide facile strategies to construct C-S/O bonds, and expand the methods of synthesizing sulfanylfurans. In this transformation, various groups on homopropargylic alcohols and sulfonyl hydrazides react smoothly and the desired sulfanylfurans are obtained in moderate to good yields.

tert-Butyl nitrite (TBN) as the N atom source for the synthesis of substituted cinnolines with 2-vinylanilines and a relevant mechanism was studied.

A green method to synthesize cinnolines by 6π electrocyclic reaction with alkenyl amines and TBN has been developed. TBN plays a dual role both as a nitrogen atom source and an oxidant in this procedure. Relevant mechanism experiments reveal that the reaction proceeds through electrocyclic reaction and with diazo hydroxide as a key intermediate.

Copper-Mediated Aerobic Oxidative Synthesis of 3-Bromo-imidazo[1,2-a]pyridines with Pyridines and Enamides.

A conversion of pyridines and enamides for the synthesis of 3-bromo-imidazo[1,2-a]pyridines was developed by copper-mediated aerobic oxidative coupling in a one-pot manner. This procedure tolerates various functional groups and affords a series of 3-bromo-imidazo[1,2-a]pyridines under mild conditions.

Iodine-mediated thiolation of substituted naphthols/naphthylamines and arylsulfonyl hydrazides via C(sp2)-H bond functionalization.

A direct method has been developed for iodine-mediated thiolation of naphthols/naphthylamines and arylsulfonyl hydrazides through the formation of C-S bond and cleavage of S-N/S-O bonds. In this transformation, a range of valuable thioethers are easily achieved in moderate to good yields.

I2-catalyzed synthesis of substituted pyrroles from α-amino carbonyl compounds and aldehydes.

A direct method for the synthesis of 1,3,4-triarylpyrroles was achieved easily from cyclization of α-amino carbonyl compounds and aldehydes catalyzed by I2. Various substituted groups can be employed, and this reaction can proceed smoothly in moderate to good yields.

I2-mediated oxidative cyclization for synthesis of substituted indolizines.

A direct method for the synthesis of substituted indolizines by means of I2-mediated oxidative tandem cyclization via C-N/C-C bond formation was developed. Various substituted aromatic/aliphatic enolizable aldehydes and 2-pyridylacetates/acetonitrile/acetone proceeded smoothly in this transformation, and the desired products were generated in moderate to good yields.

I2-catalyzed synthesis of 3-aminopyrrole with homopropargylic amines and nitrosoarenes.

The synthesis of 3-aminopyrrole using the amination reagent nitrosoarenes and homopropargylic amines catalyzed by I2 through cyclization and amination has been developed. This protocol features excellent functional group tolerance and mild reaction conditions, yielding 3-aminopyrroles in moderate to good yields without a metal catalyst. This method realizes the construction and amination of the 3-aminopyrroles in which nitrosoarenes serve as the amine source and oxidant.

I2-Mediated [6 + 1] Annulation of Alkynes with MsONH3OTf: Direct Synthesis of Benzo[b]azepines.

The synthesis of benzo[b]azepines using protonated aminating reagent (MsONH3OTf) and alkynes through I2-mediated [6 + 1] annulation reaction has been developed. This protocol features excellent functional group tolerance and mild reaction conditions and affords the benzo[b]azepines in moderate to good yields under metal-free reaction conditions.

Bi(III)-catalyzed intermolecular reactions of (Z)-pent-2-en-4-yl acetates with ethynylarenes for the construction of multisubstituted fluorene skeletons through a cascade electrophilic addition/cycloisomerization sequence.

A Bi(III)-catalyzed method for the synthesis of highly conjugated aromatic multisubstituted fluorene with (Z)-pent-2-en-4-yl acetates and ethynylarenes via domino reaction is described. In this process, the reaction appears to be very general and suitable for a variety of multisubstituted fluorene.

Cu(I)-catalyzed synthesis of imidazo[1,2-a]pyridines from aminopyridines and nitroolefins using air as the oxidant.

A copper-catalyzed method for the synthesis of imidazo[1,2-a]pyridines with aminopyridines and nitroolefins using air as oxidation agent in a one-pot procedure has been developed. In this process, the reaction appears to be very general and suitable for construction of a variety of imidazo[1,2-a]pyridines.

Pd(II)-catalyzed synthesis of benzisoxazolones from benzohydroxamic acids via C-H activation.

A Pd-catalyzed method for the synthesis of benzisoxazolones from benzohydroxamic acids using Oxone as an oxidant in a one-pot procedure has been developed. In this process, the reaction appears to be suitable for construction of various benzisoxazolones.

Palladium-catalyzed divergent reactions of 1,6-enyne carbonates: synthesis of vinylidenepyridines and vinylidenepyrrolidines.

A method for preparing five- or six-membered heterocyclic compounds from enyne carbonates via palladium catalysis was developed. Enyne carbonates were transformed into 3-vinylidene-1-tosylpyridines 2 in the presence of PdI(2) as the catalyst. Using Pd(dba)(2) as the catalyst, 3-vinylidene-1-tosylpyrrolidines 3 were obtained. Further functionalizations of compounds 3 were carried out in a one-pot manner.

Iron-Catalyzed Ring Expansion of Cyclobutanols for the Synthesis of 1-Pyrrolines by Using MsONH3OTf.

The synthesis of 1-pyrrolines from cyclobutanol derivatives and an aminating reagent (MsONH3OTf) has been developed. This one-pot procedure achieves C-N bond/C═N bond formation via ring expansion. A series of 1-pyrroline derivatives are synthesized in moderate to good yields under mild conditions.