First syntheses of 2-hydrogeno-2-oxo-1,4,2-oxazaphosphinanes via intramolecular esterification

Synthesis of 2-hydrogeno-2-oxo-1,4,2-oxazaphosphinanes via either intramolecular transesterification, using potassium tert-butylate as catalytic agent, or phosphinic acid esterification, is described for the first time.     

Pallado-catalysed P-arylations and P-vinylation of 2-hydrogeno-2-oxo-1,4,2-oxazaphosphinanes

A simple and effective preparation of 2-aryl- (or 2-vinyl)-1,4,2-oxazaphosphinanes, phosphorus analogues of aryl-morpholinols has been developed, involving palladium catalysed coupling of aryl (or vinyl)-halides with 2-H-1,4,2-oxazaphosphinane in presence of triethylamine. A deprotection step was also proposed to afford the corresponding P-aryl-α-aminobenzylphosphinic acid.     

Synthesis of 1,4,2-dioxaphosphepanes by the reaction of 2-fluoroalkoxy-4-oxo-5,6-benzo-1,3,2-dioxaphosphorinanes with chloral

The reaction of 2-fluoroalkoxy-5,6-benzo-1,3,2-dioxaphosphorinanes with chloral leads to the formation of ring expansion products with a P-C bond, namely, 2-fluoroalkoxy-2,5-dioxo-3-trichloromethyl-6,7-benzo-1,4,2-dioxaphosphepanes with high stereoselectivity.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1676–1678, July, 1991.     

Synthesis of aza-heterocycles from oximes by amino-Heck reaction

Oxidative addition of oximes to palladium(0) complexes generates alkylideneaminopalladium(II) species, which are utilized as key intermediates for carbon-nitrogen bond formation. Various aza-heterocycles, such as pyrrole, pyridine, isoquinoline, spiroimine, and azaazulene, can be synthesized from O-pentafluorobenzoyloximes having an olefinic moiety via an intramolecular Heck-type reaction (amino-Heck reaction) by treatment with a catalytic amount of a Pd(0) complex.     

Synthesis ofN-methacryloyl- andN-allyl-substituted derivatives of ethyl 5-oxo-2-pyrrolidinecarboxylate

A method for the preparation of previously unknownN-methacryloyl- andN-allyl-derivatives of ethyl 5-oxo-2-pyrrolidinecarboxylate has been developed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 767–769, March, 1996.     

Synthesis of fully substituted pyrano[2,3-c]pyrazole derivatives via a multicomponent reaction of isocyanides

The three-component reaction of the zwitterions generated from dialkyl acetylenedicarboxylate and isocyanides with 3-methyl-1-phenyl-1H-pyrazol-5(4H)-one is described. The reaction afforded the corresponding special type of fully substituted pyrano[2,3-c]pyrazole derivatives in good yields without using any catalyst and activation.     

Synthesis of 1,4-benzothiazin-2-yl derivatives of 1,3-dicarbonyl compounds and benzothiazinone spiro derivatives by the reaction of 2-chloro-1,4-benzothiazin-3-ones with ‘push-pull’ enamines

The reaction of 2-chloro-3-oxo-3,4-dihydro-2H-1,4-benzothiazines with ‘push-pull’ enamines was investigated. The reaction with the enamines occurs at the β-carbon atom in the presence of a small excess of triethylamine. As a result, a set of 3-oxo-3,4-dihydro-2H-1,4-benzothiazin-2-yl derivatives of 1,3-dicarbonyl compounds and benzothiazinone spiro derivatives was prepared. On acidic hydrolysis of ethyl 2-ethyl-3-(methylimino)-2-(3-oxo-3,4-dihydro-2H-1,4-benzothiazin-2-yl)butanoate, a new rearrangement affording ethyl 11-ethyl-2,3-dimethyl-4-oxo-2,3,4,5-tetrahydro-1H-2,5-methano-6,1,3-benzothiadiazocine-11-carboxylate was discovered. A plausible mechanism and factors influencing the course of the reaction are discussed.     

Synthesis of isoquinolone via rhodium(III)-catalyzed C-H activation with 1,4,2-dioxazol-5-ones as oxidizing directing group

An efficient rhodium-catalyzed direct C-H activation for the synthesis of isoquinolone with 1,4,2-dioxazol-5-ones as oxidizing directing groups have been developed, which featured mild reaction conditions, short reaction time and satisfactory yield.     

Synthesis of polyhydroquinoline derivatives through unsymmetric Hantzsch reaction using organocatalysts

A novel and green approach for efficient and rapid synthesis of polyhydroquinoline derivatives via unsymmetric Hantzsch reaction using organocatalysts at room temperature was reported. The process is a simple, environmentally friendly, rapid, and high yielding reaction for the synthesis of polyhydroquinoline derivatives. The catalytic efficiency of various small organocatalysts such as l-proline, trans-4-hydroxy-l-proline, l-thiaproline, dl-phenylglycine, and (−)-cinchonidine was studied under aqueous, organic, and solvent free conditions.     

Camphor-derived thioureas: Synthesis and application in asymmetric Kabachnik-Fields reaction

A series of camphor-derived thiourea organocatalysts 3a–f were designed and synthesized from(1R,3S)-camphoric acid 1 and applied to the one-pot three-component Kabachnik–Fields reaction. Catalyst 3c was found to be an efficient organocatalyst for the reaction of 2-cyclopropylpyrimidin-4-carbaldehyde 4,various amines 5, and diphenylphosphite 6 to yield the corresponding enantioselective a-aminophosphonates 7a–e in 74%–82% yields and 14%–35% ee.     

Application of Ugi three component reaction for the synthesis of quinapril hydrochloride

Abstract

A novel, efficient and concise synthesis of chirally pure quinapril hydrochloride is described. The key step is the formation of α-amino amide backbone in one step using Ugi three component reaction. This method allows short access to α-amino amide chain which is a part of many drugs used for treatment of high blood pressure. A large molecular library can be synthesized by changing the components in Ugi reaction.     

Reaction of R-(+)-2-benzylideneaminobutan-1-ol with ethylene phosphorochloridite. Stereospecific formation of (3R,5R)-2-(2-chloroethoxy)-5-ethyl-2-oxo-3-phenyl-1,4,2-oxazaphosphorinane

The reaction of R-(+)-2-benzylideneaminobutan-1-ol with ethylene phosphorochloridite afforded phosphorus-epimeric (3R,5R)-2-(2-chloroethoxy)-5-ethyl-2-oxo-3-phenyl-1,4,2-oxazaphosphorinanes. The phosphorinane-ring closure proceeded stereospecifically and occurred only from one of the diastereofacial sides (re) of the C=N bond.     

Assembly of homoallylamine derivatives through iron‐catalyzed three‐component sulfonamidoallylation reaction

An efficient FeCl₃‐catalyzed three‐component reaction between aldehydes, sulfonamides and allylsilanes has been achieved, which provides a convenient, atom‐economic and green way to construct homoallylamine derivatives. In addition, this reaction exhibits excellent syn stereoselectivity with γ‐substituted allylsilanes.     

Synthesis of pyrimidine derivatives via multicomponent reaction catalyzed by ferric chloride

An eco-friendly and practical approach was developed for the synthesis of pyrimidine derivatives via a one-pot, three-component coupling reaction of commercially available aldehydes, alkynes, and indazole3/triazole catalyzed by ferric chloride with good to excellent yields. The advantages of this method include environmentally friendly catalyst, easily available materials, and ease of product isolation.     

Regioselective synthesis of 2-carbonyl furans in a one pot three component reaction

Regioselective synthesis of 2-benzoyl-6,6-dimethyl-6,7-dihydrobenzofuran-4(5H)-ones have been accomplished through a novel protocol involving β-amino enone, N-chlorosuccinimide and dimedone in a one pot catalyst-free reaction at an ambient temperature. On the other hand, the same reaction when conducted with two equivalents of N-chlorosuccinimide under similar reaction conditions, exclusive formation of 2-benzoyl-3-(dimethylamino)-6,6-dimethyl-6,7-dihydrobenzofuran-4(5H)-ones were observed. Simple and metal-free reaction conditions, selective product formation and excellent yields are the advantages of this protocol.     

Synthesis of Annulated Indolines by Reductive Fischer Indolization

Cyclic β-oxoesters and arylhydrazine derivatives were converted at ambient temperature under modified Fischer indolization conditions to furnish annulated indolines with quaternary bridgehead carbon center. Reaction conditions were Brønsted acidic (with CF₃CO₂H), but also reductive (with Et₃SiH). The latter reduced intermediate iminium ions under formation of the 2,3-dihydroindole product constitutions. Racemic products (13 examples) were obtained as single diastereoisomers with relative cis-configuration, which was proved in two cases by single-crystal X-ray structure analysis. Conversion of 4-bromo-1-indanone-2-carboxylate and 4-bromophenylhydrazine gave indeno[1,2-b]indolines with either 1-bromo, 8-bromo, or 1,8-dibromo substitution, which were further diversified by Suzuki coupling reactions with several arylboronic acids (nine examples).     

Synthesis of 2-arylmethylidene-5-oxo-1,4-diphenyl-2,5-dihydro-1H-pyrazol-2-ium-3-olates

Condensation of several arylhydrazones with chlorocarbonyl phenyl ketene gave 2-(arylmethylidene)-5-oxo-1,4-diphenyl-2,5-dihydro-1H-pyrazol-2-ium-3-olates in high yields.     

Synthesis of polysubstituted pyrroles via a gold(I)-catalyzed tandem three-component reaction at room temperature

A gold(I)-catalyzed three-component reaction of β-nitrostyrenes with 1,3-dicarbonyl compounds and primary amines to form polysubstituted pyrroles has been developed at room temperature in ethanol. The key advantages of the three-component reaction are the mild reaction conditions and environm entally safer solvent