Efficient microwave-assisted synthesis of 5-deazaflavine derivatives

A series of pyrimido[4,5-b]quinolines (5-deazaflavines), were synthesized by microwave assisted intramolecular cyclization. The N?-substituted-2,4-diamino-6-chloro-pyrimidine-5-carbaldehydes, were prepared by selective monoamination of 2-amino-4,6-dichloropyrimidine-5-carbaldehyde with aliphatic and aromatic amines.     

A facile and expeditious microwave-assisted synthesis of 4-aryl-2-ferrocenyl-quinoline derivatives via multi-component reaction

An efficient and rapid route for the synthesis of 4-aryl-2-ferrocenyl-quinoline derivatives through microwave-assisted multi-component reaction of acetylferrocene with aromatic aldehyde and dimedone in the presence of ammonium acetate using DMF as reaction media at 100 °C is described. This novel procedure lends itself well to combinatorial methods, providing the target heteropolymetallic compounds in excellent yield without further purification.     

An efficient and expeditious microwave-assisted synthesis of 4-azafluorenones via a multi-component reaction

An efficient and expeditious microwave-assisted synthesis of 4-azafluorenone derivatives and related compounds is accomplished via a multi-component reaction of an aldehyde, 1,3-indanedione, an arone and ammonium acetate. It is an efficient and promising synthetic strategy to build indenopyridine skeleton.     

An expeditious synthesis of anthracyclines

Regiospecific cycloaddition of 2-oxybutadienes to derivatives of the 1,4-anthraquinone (6) efficiently leads to the tetracyclic ketones (4) and (5), which previously have been converted into daunomycin, adriamycin and related anticancer agents.     

An expeditious synthesis of 6-aminophenanthridines

A simple synthesis of biologically active 6-aminophenanthridines was achieved by a Suzuki-Miyaura coupling reaction. Condensation of 2-(4,4,5,5-tetramethyl-1,3-dioxaborolan-2-yl)aniline with 2-chlorobenzonitriles afforded 6-aminophenanthridines useful as prions inhibitors in a mild one-step procedure. The intermediate 2-amino-2′cyanobiphenyls could not be isolated.     

Novel and expeditious microwave-assisted three-component reactions for the synthesis of spiroimidazolin-4-ones

Highly efficient methods for the syntheses of spiroimidazolinones via microwave-assisted three-component one-pot sequential reactions or one-pot domino reactions are described. The efficiency and utility of the methods have been demonstrated by quickly accessing the antihypertensive drug irbesartan (2).     

An expeditious and convergent synthesis of ailanthoidol

An expeditious and concise method has been described for the synthesis of ailanthoidol through convergent route starting from vanillin. The protocol involving intramolecular Wittig as a key reaction afforded ailanthoidol in overall high yield.     

Facile microwave-assisted synthesis of substituted benzofuran derivatives

A series of benzofuran derivatives have been synthesized by use of a microwave-assisted process. Substituted or unsubstituted ο-hydroxyacetophenone and salicylaldehyde reacted with ethyl bromoacetate, ω-bromoacetophenone, or chloroacetone under the action of potassium carbonate in DMF to yield substituted benzofuran derivatives. Compared with conventional heating, this microwave-assisted synthetic process has the advantages of more convenient operation, shorter reaction time, and higher yield.     

An expeditious enantioselective total synthesis of valilactone

The title compound was synthesized through an expeditious route using Crimmins aldolization to establish the two key stereogenic centers and a hydroxyl group activation (HGA) protocol to construct the anti alpha,beta-disubstituted beta-lactone from the corresponding syn aldol.     

An expeditious synthesis of tailed tren-capped porphyrins

[structure: see text] A one-pot two-step versatile synthesis of tailed tren-capped porphyrins has been achieved. The two resulting ligands demonstrate that this expeditious method can be applied to various axial bases to obtain highly functionalized macromolecules attractive for heme modeling purposes. Dioxygen binding of the pyridine-tailed iron complex is reported as a direct application.     

An efficient and expeditious microwave‐assisted synthesis of quinoxaline derivatives via nucleophilic heteroaromatic substitution

A series of 2‐substituted quinoxaline derivatives including five novel compounds have been successfully synthesized from 2‐chloroquinoxaline using microwave methodology. The yields of the quinoxalines synthesized through this method, were an improvement over the thermal methods usually employed.     

An expeditious synthesis of DPD and boron binding studies

A practical synthesis has been developed for DPD (4,5-dihydroxypentane-2,3-dione), an unstable small molecule that is proposed to be the source of universal signaling agents for quorum sensing in bacteria. The synthesis allows preparation of isotopically labeled DPD and ent-DPD as well as detailed studies of spontaneous binding to borate to give the unusual borate complex 6, the signal for marine bacteria such as Vibrio harveyi. [reaction: see text]     

Efficient microwave-assisted synthesis of highly functionalized pyrimidine derivatives

A generally applicable one-pot procedure for the rapid, easy, and diverse asymmetric functionalization of pyrimidines was developed that requires minimum efforts for the purification of the final products. 4-Amino-6-aryl-substituted pyrimidines are prepared in good yields by combined microwave-assisted amination and Suzuki-Miyaura cross-coupling reactions. The acid-mediated amination reaction affords the products as easily separable salts in 30-40 min reaction time.     

An efficient and simple aqueous N-heterocyclization of aniline derivatives: microwave-assisted synthesis of N-aryl azacycloalkanes

[reaction: see text] An efficient and clean synthesis of N-aryl azacycloalkanes from alkyl dihalides and aniline derivatives has been achieved using microwave irradiation in an aqueous potassium carbonate medium. The phase separation can simplify the product isolation and reduce usage of volatile organic solvents.     

An expeditious synthesis of natural and unnatural disubstituted maleic anhydrides

A facile entry to the synthesis of natural and unnatural substituted maleic anhydrides based on the Barton radical decarboxylation is described. The radicals, generated by the photolysis of N-hydroxy-2-thiopyridone esters derived from succinic and alkyl acids reacted, respectively, with electron deficient olefin phenyl maleimide by a consecutive two-step radical addition, afforded the corresponding disubstituted maleic anhydrides 1a-f.     

An expeditious synthesis of 4-fluoropiperidines via aza-Prins cyclization

The reaction of aldehydes with N-tosyl homoallylamine in the presence of a solution of tetrafluoroboric acid-diethyl ether complex in dichloromethane at ambient temperature gave the 4-fluoropiperidines in good yields and with high cis-selectivity. This aza-Prins-type cyclization has a wide scope and the use of HBF₄·OEt₂ makes this procedure simple, convenient, and cost-effective for the preparation of 4-fluoropiperidines.     

An expeditious total synthesis of (+/-)-stenine

(+/-)-Stenine was synthesized in eight steps from a known ketophosphonate reagent. The key step was an exo-selective Diels-Alder/intramolecular Schmidt domino reaction that afforded three of the four rings and four stereocenters in a single reaction.     

An expeditious,solvent-free synthesis of some 5-aryl-2-(2-hydroxyphenyl)-1,3,4-oxadiazoles

An efficient, rapid, microwave-accelerated one-step synthesis of some 5-aryl-2-(2-hydroxy-phenyl)-1,3,4-oxadiazoles by reaction of salicylic hydrazide with carboxylic acids in the presence of thionyl chloride under neat conditions is described. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1264–1267, August, 2007.     

An expeditious and convenient synthesis of acylsulfonamides utilizing polymer-supported reagents

Acylsulfonamides can be rapidly and conveniently synthesized from a variety of carboxylic acids and sulfonamides utilizing the commercially available reagents, PS-DCC and DMAP under mild reaction conditions. DMAP can be efficiently scavenged by utilization of a silica-supported tosic acid cartridge (Si-SCX). In most of the cases studied, products with high purities and yields were obtained without the need for further purification.