Efficient synthesis of highly substituted thiophenes from acetylenic esters, ethyl bromopyruvate, and tetramethylthiourea

The reaction of acetylenic esters with ethyl bromopyruvate in the presence of tetramethylthiourea led to highly functionalized thiophenes in excellent yields.     

Efficient synthesis of 2,3,4-trisubstituted furans from the reaction of activated acetylenes with ethyl bromopyruvate in the presence of enaminones

The reaction of dialkyl acetylenedicarboxylates or diaroylacetylenes with ethyl bromopyruvate in the presence of enaminones led to 2-ethyl 3,4-dialkyl 4-bromo-4,5-dihydro-2,3,4-furantricarboxylates or ethyl 3,4-diaroyl-4-bromo-4,5-dihydro-2-furancarboxylate in excellent yields. These compounds are quantitatively converted to the corresponding 2,3,4-trisubstituted furans by 4-dimethylaminopyridine. Correspondence: Issa Yavari, Chemistry Department, Tarbiat Modares University, PO Box 14115-175, Tehran, Iran.     

Efficient synthesis of tetrasubstituted thiophenes by reaction of benzoyl isothiocyanates, ethyl bromopyruvate and enaminones

An efficient synthesis of ethyl 2-(4-acetyl-5-benzoylamino-3-methyl-2-thienyl)-2-oxoacetates is described via reaction between benzoyl isothiocyanates and ethyl bromopyruvate in the presence of enaminones.     

Efficient synthesis of 2-thioxo-1,3-thiazolanes from primary amines, CS2, and ethyl bromopyruvate

An efficient synthesis of 2-thioxo-1,3-thiazolanes is described via reaction of carbon disulfide, ethyl bromopyruvate, and primary amines. Correspondence: Issa Yavari, Chemistry Department, Tarbiat Modares University, PO Box 14115-175, Tehran, Iran.     

An efficient and facile one-step synthesis of highly substituted thiophenes

An efficient one-step method for the synthesis of fully substituted thiophenes, from thiomorpholides and α-halo ketones, was developed. A mechanism has also been proposed for the course of reaction.     

A synthesis of pyrrolo[2,1-a]isoquinolines through the reaction of activated acetylenes and isoquinoline in the presence of ethyl bromopyruvate

Isoquinoline reacts with ethyl bromopyruvate in the presence of dialkyl acetylenedicarboxylates or diaryloylacetylenes to produce dialkyl 1-(2-ethoxy-2-oxoacetyl)pyrrolo[2,1-a]isoquinoline-2,3-dicarboxylates or ethyl 2-[2,3-diaryloylpyrrolo[2,1-a]isoquinoline-1-yl]-2-oxoacetates in good yields.     

A practical, one-pot synthesis of highly substituted thiophenes and benzo[b]thiophenes from bromoenynes and o-alkynylbromobenzenes

An efficient synthesis of thiophenes and benzo[b]thiophenes has been developed from easily available bromoenynes and o-alkynylbromobenzene derivatives. This novel one-pot procedure involves a Pd-catalyzed C-S bond formation using a hydrogen sulfide surrogate followed by a heterocyclization reaction. Moreover, in situ functionalization with selected electrophiles further expands the potential of this methodology to the preparation of the corresponding highly substituted sulfur heterocycles.     

One-pot synthesis of new tetrasubstituted thiophenes and selenophenes

In this work, we described the synthesis of new tetrasubstituted thiophenes and selenophenes achieved by an easy one-pot four-step procedure. Expected compounds were obtained in good yield from ketene dithioacetals.     

One-pot synthesis of highly functionalized 1,2-dihydropyridines from primary alkylamines, alkyl isocyanides, and acetylenic esters

A novel one-pot isocyanide-based cascade four-component reaction between primary alkylamines, acetylenic esters, and alkyl isocyanides led to tetraalkyl 1-alkyl(aryl)-4-alkylamino-1,2-dihydropyridine-2,3,5,6-tetracarbxylates in good yields.     

Efficient Synthesis of Pyrrolo[1,2-f]phenanthridine Derivatives via Dipolar Cycloaddition of Phenanthridine,Activated Acetylenes,and Ethyl Bromopyruvate

The three-component reactions of phenanthridine, activated acetylenes, and ethyl bromopyruvate through both of simultaneous and stepwise process are surveyed. The reactions afforded the corresponding pyrrolo[1,2-f]phenanthridine derivatives in good yields without using any catalyst and activation.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.]     

Palladium-catalyzed synthesis of substituted cyclopentadienes and indenes from allylic esters

Various mono- and di-substituted cyclopentadienes have been prepared by palladium-catalyzed alkylation of allylic esters with cyclopentadienide and t-butyl-cyclopentadienide anions. The same procedure has been applied to the preparation of substituted indenes.     

DABCO catalyzed facile synthesis of highly functionalized pyrazolines from Baylis-Hillman acetates and ethyl diazoacetate

A convenient synthesis of pyrazolines is reported via DABCO mediated reaction of ethyl diazoacetate (EDA) with Baylis-Hillman acetates. The products were obtained in good to excellent yields (70-95%).     

One-pot synthesis of functionalized thioureas by reaction of benzoyl isothiocyanates, secondary amines, and alkyl propiolates

An efficient one-pot synthesis of functionalized thioureas is described via three-component reaction of benzoyl isothiocyanates, secondary amines, and alkyl propiolates in the presence of triphenylphosphine (20 mol%). Correspondence: Issa Yavari, Chemistry Department, Tarbiat Modares University, PO Box 14115-175, Tehran, Iran     

Efficient synthesis of highly functionalized vinylogous thiol esters

A series of vinylogous thiol esters 2,3 and 2,6-dioxo-1,2,5,6-tetrahydropyridines (cyclic vinylogous thiol esters) 4 were prepared in high to excellent yields from the tandem reaction of readily available α-alkenoylketene diethylthioacetals 1 and diethyl malonate. A plausible mechanism, which involves a base catalyzed retro-Michael ring opening of cyclohexanenes 2 to give vinylogous thiol ester 3, is disclosed.     

Cascade reactions forming highly substituted, conjugated phospholes and 1,2-oxaphospholes

More than just a carbon copy: The reaction of a phospha-Wittig-Horner reagent with diacetylenic ketones (see scheme) results in a cascade of reactions that can lead to both an oxaphosphole-terminated cumulene system and an alkene-bridged bis-phosphole. The reaction outcome is determined by the nature of the acetylene termini, with phenyl groups stabilizing a carbene intermediate that dimerizes to give the bis-phosphole product.     

Expedient synthesis of substituted imidazoles from nitriles

Expedient and practical new methodology for the synthesis of substituted imidazoles was developed to provide a rapid access to a variety of 2-substituted, 1,2-disubstituted and 1,2,4-trisubstituted imidazoles by the direct CuCl-mediated reaction of nitriles with α-amino acetals in an intermolecular as well as intramolecular fashion.     

Synthesis of substituted esters of imidazoles,oxazoles, thiazoles,and diethyl pyrazine-2,5-dicarboxylate from a common acyclic precursor employing C-formylation strategy

A novel synthetic route to substituted esters of imidazoles, oxazoles, thiazoles, and diethyl pyrazine-2,5-dicarboxylates via C-formylation of glycine ethyl ester hydrochloride is reported. This methodology is simple, robust, and gives good yields of different heterocyclic esters in one or two steps from a common acyclic precursor and is amenable to large scale synthesis.     

Efficient one-pot synthesis of highly substituted thiophene library from 1,3-dicarbonyl compounds

A facile and efficient one-pot synthesis of highly substituted thiophenes has been developed and employed for the preparation of a small focused library. Treatment of 1,3-dicarbonyl compounds 1 with CS2 in the presence of K2CO3 in DMF at room temperature, followed by stepwise addition of alkyl bromides 2 and methylene active bromides 3, provided via intramolecular cyclization 2,3,4,5-tetrasubstituted thiophenes 4 in yields of 77-94%. This protocol, combining construction and modification of the thiophene ring, increases the structural diversity of final products from readily available materials. A mechanism for the one-pot synthesis of thiophenes of type 4 has been proposed. A small focused library of thiophenes is prepared using the sequential addition of reagents to achieve unique substitution in the 2 and 5 position of the thiophene ring.