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Primary and secondary benzylic and aliphatic alcohols are efficiently oxidized to the corresponding carbonyl compounds.

A new and unusual method for the synthesis of the title compounds (III) (8 examples) is developed involving ring-opening of coumarin-based dihydrobenzothiazoles (I) and subsequent [4 + 1] cycloaddition reaction with isocyanides (II).

A mild, simple and efficient methodology for the preparation of sterically congested title oxadiazole compounds (V) (12 examples) is reported.

The title reaction represents a rapid and unprecedented route for the synthesis of 1,3-thiazolethione derivatives with expected biological activity.

An efficient triethylamine-catalyzed synthesis of 4-amino-3,5-dicyano-6-arylphthalates is described. A one-pot, simple pseudo four-component reaction between arylaldehydes, dialkyl acetylenedicarboxylates, and twice as much malononitrile gave 4-amino-3,5-dicyano-6-arylphthalates in good to excellent yields.

The 1:1 imine intermediate generated by the addition of primary amine to chloroacetone derivatives is trapped by N-isocyaniminotriphenylphosphorane in the presence of phenylacetylenecarboxylic acid, leading to the formation of the corresponding iminophosphorane intermediate. Disubstituted 1,3,4-oxadiazole derivatives are formed via intramolecular aza-Wittig reaction of the iminophosphorane intermediate. The reactions were completed in neutral conditions at room temperature. The disubstituted 1,3,4-oxadiazole derivatives were prepared in excellent yields. Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file.

A variety of (Z)-[(2H-chromen-3-yl)methylene]azolidinones 6a-t bearing thiazolidine-2,4-dione, rhodanine or hydantoin scaffolds were designed and synthesized as potential anticancer agents. Inhibitory effect of synthesized compounds 6a-t on the viability of cancer and non-cancer cells was assessed using MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) reduction assay. The SAR study revealed that the N-substitution of azolidinone moiety cannot improve the activity but S/NH replacement (thiazolidine-2,4-dione/hydantoin) and S/O alteration (rhodanine/thiazolidine-2,4-dione) enable us to modulate the growth inhibition activity against various cell lines. Moreover, 6-bromo and 2-methyl substituents on chromene ring had positive effects on growth inhibitory activity depending on the tumor cell lines. Among the synthesized compounds, hydantoin derivative 6o with a 6-bromo-2-methyl-2H-chromene substructure showed the best profile of cytotoxicity comparable to that of cisplatin as standard anticancer agent.

Reactions of N-isocyaniminotriphenylphosphorane with ester derivatives of 2-oxopropyl alcohol (2-oxopropyl 4-bromobenzoate, 2-oxopropyl benzoate, and 2-oxopropyl acetate) in the presence of aromatic carboxylic acids proceed smoothly at room temperature and in neutral conditions to afford sterically congested 1,3,4-oxadiazole derivatives in high yields. The reaction proceeds smoothly and cleanly under mild conditions and no side reactions were observed.

A facile and fairly efficient procedure for the synthesis of the title compounds is described by using an environmentally benign solvent and a cheap oxidant.

The iminium intermediate generatedby the reaction between a secondary amine andcinnamaldehyde was reacted with N-isocyanimino-triphenylphosphorane in the presence of benzoic acidderivatives to form the corresponding iminophospho-rane intermediate, whose intramolecular aza-Wittigreaction led to disubstituted 1,3,4-oxadiazole deriva-tives. The syntheses were completed under neutralconditions at room temperature to give excellentyields. 2012 Wiley Periodicals, Inc. Heteroatom Chem C23:315–321, 2012; View this article online at wileyonlineli-brary.com. DOI 10.1002/hc.21013 INTRODUCTION 1,3,4-Oxadiadoles have attracted interest in medici-nal chemistry as surrogates of carboxylic acid. Theyare an important class of heterocyclic compoundsthat have a wide range of pharmaceutical and Correspondence to: Ali Ramazani; e-mail: aliramazani@gmail.com. c 2012 Wiley Periodicals, Inc. biological activities such as antimicrobial, antifun-gal, antimalarial, analgesic, hypoglycemic, and an-tihypertensive anti-Inflammatory [1–5]. The multi-component condensation reactions give advantagesto other reactions. In recent years, several tech-niques have been reported for the preparation ofCNNPPh

An efficient synthesis of the title compounds (III), (V), and (VII) is presented by using the cheap and commercially available quinine hydrochloride as the catalyst of choice

The mild and efficient synthesis of the title compounds (III) is presented including an easy work-up and without the need of any purification.

A facile one-pot, multicomponent method for the synthesis of 2-phosphono-substituted furans (V) is described and a reasonable reaction mechanism is proposed.

The multicomponent reaction between oxopropylbenzoate(acetate) (I), (VI), primary amines (II), (N-isocyanimino)triphenylphosphorane (III), and aromatic carboxylic acids (IV) proceeds smoothly at room temperature under neutral conditions to afford the sterically congested oxadiazole derivatives (V) and (VII), resp.

Multicomponent reaction of o-formylbenzoic acid derivative (I) with secondary amines (III) and isocyanides (II) proceeds smoothly in the presence of silica nanoparticles under neat conditions to give dihydroisoindolone derivatives (IV) in good yields.

Novel α-acyloxycarboxamides (IV) (15 examples) are synthesized via Passerini reaction in water.

Reaction of coumarin derivatives with aminothiophenols affords the benzothiazoline derivatives (III) and benzothiazole analogue (V) which can be further derivatized by alkylation reactions.

The reaction of (E)-3-aryl-2-propenoic acid derivatives with (N-isocyanimino) triphenylphosphorane proceeds smoothly at room temperature to afford the corresponding 2-[(E)-2-aryl-1-ethenyl]-1,3,4-oxadiazole via an intramolecular aza-Wittig reaction in good yields under neutral conditions. The structures of the products were deduced from their IR, 1H NMR, and 13C NMR spectra and mass spectrometry. © 2011 Wiley Periodicals, Inc. Heteroatom Chem 22:612–616, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/hc.20701

Reactions of (N-isocyanimino)triphenylphosphorane with aromatic bis-aldehydes (isophthalaldehyde and terphthalaldehyde) in the presence of aromatic (or heteroaromatic) carboxylic acids proceed smoothly at room temperature and in neutral conditions to afford sterically congested 1,3,4-oxadiazole derivatives in good yields. The reaction proceeds smoothly and cleanly under mild conditions, and no side reactions were observed.

Reactions of (N-isocyanimino)triphenylphosphorane with N,N-dicyclohexylcarbodiimide in the presence of aromatic (or heteroaromatic) carboxylic acids proceed smoothly at room temperature and in neutral conditions to afford sterically congested 1,3,4-oxadiazole derivatives in high yields. The reaction proceeds smoothly and cleanly under mild conditions, and no side reactions were observed.

The 1:1 imine intermediate generated by the addition of benzyl amine to cyclobutanone is trapped by (N-isocyanimino)triphenylphosphorane in the presence of an aromatic carboxylic acid leads to the formation of the corresponding iminophosphorane intermediate. Disubstituted 1,3,4-oxadiazole derivatives are formed via intramolecular aza-Wittig reaction of the iminophosphorane intermediate. The reactions were completed in neutral conditions at room temperature. The disubstituted 1,3,4-oxadiazole derivatives, were produced in excellent yields.

The reaction is applied to a variety of benzylic amines and allylamine and tolerates a range of functional groups in the carboxylic acids.

Dialkyl 2-(alkylamino)-4,9-dihydro-9-oxocyclohepta[b]pyran-3,4-dicarboxylates are prepared in a one-pot three-component reaction of alkyl isocyanide, dialkyl acetylenedicarboxylate, and α-tropolone (=2-hydroxycyclohepta-2,4,6-trienone). The reaction proceeds smoothly at room temperature and under neutral conditions to afford tropolone derivatives in high yield.

Reaction of an isocyanide with an iminium ion intermediate, formed by reaction between 2-formylbenzoic acid and dibenzylamine in the presence of silica nanoparticles (silica NP, ca. 42 nm) proceeds smoothly at room temperature to afford isocoumarin (=1H-2-benzopyran-1-one) derivatives in high yields (Scheme 1 and Table 1).

Reactions of electron-poor α-haloketones with (N-isocyanimino) triphenylphosphorane in the presence of aromatic carboxylic acids proceed smoothly at room temperature and in neutral conditions to afford disubstituted 1,3,4-oxadiazole derivatives in high yields. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 21:368–372, 2010; View this article online at wileyonlinelibrary.com. DOI 10.1002/hc.20626

A simple and effective reaction of the aromatic aldehydes(I) (VI), aromatic carboxylic acids (III), (VIII), various linear and cyclic amines (II), (VII) and isocyanimino-triphenylphosphorane (IV) leads to the formation of the desired oxadiazole in excellent yields.

Protonation of the reactive 1:1 intermediates produced in the reaction between triphenylphosphine and dialkyl acetylenedicarboxlates by butane-2,3-dione monoxime leads to vinyltriphenylphosphonium salts, which undergo intramolecular Wittig reaction to produce dialkyl 2,3-dimethyl-N-hydroxypyrrole-4,5-dicarboxylates in fairly high yields.

Protonation of the reactive intermediates produced in the reaction between dialkyl acetylenedicarboxylates and triphenylphosphine by 2-hydroxy-1-naphthaldehyde leads to vinyltriphenylphosphonium salts, which undergo intramolecular Wittig reaction to produce dialkyl 3H-naphtho[2,1-b]pyran-2,3-dicarboxylates in fairly high yields. ∗Dedicated to Professor Abbas Shafiee on the anniversary of his 60th birthday.

The conjugate addition of oximes to ethyl propiolate proceeds under neutral conditions in presence of a catalytic amount of triphenylphosphine to give the corresponding O-vinyloximes in good yields.

Dialkyl 1,2-dihydroquinoline-2,3-dicarboxylates are formed in a one-pot reaction from amide derivatives of 2-aminobenzaldehyde, dialkyl acetylenedicarboxylates and triphenylphosphine in CH 2 Cl 2 in high yields.

A one-pot synthesis of dialkyl 1-arylsulfonyl-1,2-dihydroquinoline-2,3-dicarboxylates by reaction of arylsulfonamide derivatives of 2-aminobenzaldehyde, dialkyl acetylenedicarboxylates, and triphenylphosphine in excellent yields is reported.

5-Bromo- and 5-nitro-2-hydroxybenzaldehyde react with the acetylenic ester 1 (R = Me and Bu') in the presence of triphenylphosphine to give the corresponding 6-substituted 2H-1-benzopyran-2,3-dicarboxylic esters 4. Isolated yields in the one-pot preparation of compounds 4 are excellent. Reaction mechanism for the formation of compouds 4 is proposed. The structures of compounds 4a-c have been confirmed by IR, MS and 1 H and 1 3 C NMR spectroscopy and elemental analyses.

N-Phenylacetamide and N-phenylbenzamide react with the dimethyl acetylenedicarboxylate 4 in the presence of triphenylphosphine to give the corresponding substituted highly stabilized ylides 7. Isolated yields in the one-pot preparation of compounds 7 are fairly good. Reaction mechanism for the formation of compounds 7 is proposed. The structures of compounds 7a-b have been confirmed by IR, MS and 1 H and 1 3 C NMR spectroscopy and elemental analyses. The NMR spectra indicate that the solutions of compounds 7 (CDCl 3 as solvent) contain two rotamers 8 and 9 with unequal population.

Reaction of an isocyanide with an iminium ion intermediate, formed by reaction between an electron-poor 2-hydroxybenzaldehyde derivative and a secondary amine in the presence of silica gel proceeds smoothly at room temperature to afford benzo[b]furan derivatives in high yields.