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A new facile preparation of furan-2(3 H)-ones and 2,3,5-trisubstituted furans by a sequential O-acylation/Wittig(/O-acylation) reaction has been developed. The easily accessible 2-(triphenylphosphoranylidene)-succinic acid 1-ester 3 reacted with acid chloride produced furan-2(3 H)-ones 4 in good yields in the presence of DMAP via sequential O-acylation and intramolecular Wittig reaction of acid anhydride. Subsequently, the 2,3,5-trisubstituted furans 5 were prepared from furan-2(3 H)-ones 4 and diverse aryl chlorides in presence of triethylamine through further O-acylation. Image 1 [ABSTRACT FROM AUTHOR]

A new one-pot preparation of polysubstituted quinazolin-4(3 H)-ones by a sequential oxidative Ugi/Staudinger/aza-Wittig reaction has been developed. The CuCl/TBHP/DMBP-mediated oxidative Ugi reactions of tertiary amines 1 , 2-azidobenzoic acids 2 and isocyanides 3 produced the azide intermediates, which were directly treated with triphenylphosphine to produce polysubstituted quinazolin-4(3 H)-ones 6 in moderate to good yields. [Display omitted] [ABSTRACT FROM AUTHOR]

A new one-pot and divergent synthesis of multisubstituted furo[3,2-c]quinolines and quinazolin-4(3 H)-ones via sequential isocyanide-based three-component/Staudinger/aza-Wittig reactions was developed. The three-component reactions of dialkyl acetylenedicarboxylates, 2-azidobenzaldehydes (or 2-azidobenzoic acids) and isocyanides gave the azide intermediates, which were subsequently treated with triphenylphosphine to produce polysubstituted furo[3,2-c]quinolines 6 or quinazolin-4(3 H)-ones 10 in good overall yields by tandem Staudinger/aza-Wittig reactions. Image 1 • One-pot three-component reactions. • Mild reaction conditions. • Good overall yields. [ABSTRACT FROM AUTHOR]

Abstract: Multistep microwave-assisted reactions toward the synthesis of hydantoin-fused tricyclic tetrahydro-β-carbolines on the soluble polymer support have been developed. Polymer-bound tryptophan with various aldehydes has been subjected to Pictet–Spengler reaction to obtain tricyclic β-carboline conjugates. The terminal hydantoinyl moiety is constructed across polymer-bound β-carbolines by the reaction with various isocyanates under microwave irradiation to form urea intermediate. Simultaneous intramolecular cyclization of urea followed by cleavage of the polymer support leads to a traceless synthesis of tetracyclic scaffolds in high yield and high purity. [Copyright &y& Elsevier]

An efficient one-pot synthesis of quinazolin-4(3 H )-ones, benzoimidazo[2,1- b ]quinazolin-12(6 H )-ones and imidazo[2,1- b ]quinazolin-5(1 H )-ones via a palladium-catalyzed domino process has been developed. The Pd-catalyzed reactions of 2-azidobenzamides 1 with isocyanides 2 produced quinazolin-4(3 H )-ones 4 at room temperature by a domino Pd-catalyzed cross-coupling/carbodiimide-mediated cyclization. However, as 2-azido- N -(2-bromophenyl)benzamides 1 were used under heating condition in the presence of Cs 2 CO 3 , the benzoimidazo[2,1- b ]quinazolin-12(6 H )-ones 5 were directly obtained by twice Pd-catalyzed domino cyclization. A domino reogioselective 5 -exo-dig intramolecular cyclization reaction of alkynyl-containing azides 6 with isocyanides 2 generated imidazo[2,1- b ]quinazolin-5(1 H )-ones 9 in 74–93% yields in the presence of catalyst Pd(PPh 3 ) 4 and K 2 CO 3 . [ABSTRACT FROM AUTHOR]

Abstract: The simple and efficient method was developed for the synthesis of benzimidazole linked quinoxalinones on soluble polymer support using microwave conditions. The acid catalyzed condensation of 4-fluoro-3-nitrobenzoic acid with polymer immobilized o-phenylenediamine, ipso-fluoro nucleophilic substitution with various primary amines and cyclization with acetyl chloride are the key steps involved in implemented linear synthesis. In key cyclization step, the regioselective N-acylation at secondary amine with chloroacetyl chloride followed by spontaneous intramolecular ring closure through ortho-amine functionality generate the quinoxaline skeleton under microwave irradiation. The removal of polymer support and exposure of quinoxalines for auto-oxidation finally produce the benzimidazole linked quinoxalinone derivatives with high purity and yields. [Copyright &y& Elsevier]