A simple synthesis of 2,2′-bipyrroles from pyrrole

2,2′-Bipyrroles, which are obvious precursors for the synthesis of 2,2′-bipyrrole-based natural products, are synthesized in three steps from pyrrole employing known pyrrolyl ketoalcohols by a sequential alcohol oxidation and Paal-Knorr pyrrole synthesis.     

Comparison of the reactivity between 2- and 3-nitropyrroles in cycloaddition reactions. A simple indole synthesis

N-Tosyl-2-nitropyrroles react at high temperature with poorly and strongly activated dienes. They exhibit a dienophilic character similar to N-tosyl-3-nitropyrroles producing the corresponding indoles through a classical Diels-Alder process. A similar behaviour was observed in disubstituted N-tosyl-pyrroles.     

1,2- and 1,3-diphosphetanes from alkylidenephosphines

Abstract

Alkyl- or arylbis(trimethylsilyl)phosphines as well as tris(trimethylsilyl)phosphine and the corresponding arsines react with acyl chlorides to give [1-(trimethylsiloxy)alkylidene]phosphines 1 and -arsines 2; most of their 2,2-dimethylpropylidene derivatives are thermally stable at room temperature. With the same class of phosphines as starting compounds and carbon disulfide [bis(trimethylsilylsulfano)methylidene]phosphines 3 are formed, whereas [(dialkylamino)methylidene]-4 and [diarylmethylidene]phosphines 5 or the corresponding arsines 6 and 7 can be obtained from acyl amides or ketones.¹     

Synthesis of 2′-dealkylmumbaistatin

The sterically congested 1,2,3-substituted 3′-dealkyl mumbaistatin derivatives 16, 20, and 21 were prepared for the first time by base-catalyzed cyclization of the 2,3-bis-substituted naphthoquinone precursor 11 followed by bromine mediated photooxidation and methyl ether cleavage.     

Synthesis of chiral 2′,3′-pyranone(pyrrolidinone)-fused tryptamines

Chiral pyrano- and pyrrolidino-fused tryptamines were prepared by a diasteroselective trimolecular condensation between indole, Garner's aldehyde and Meldrum's acid, followed by selective functional group transformations.     

InCl3-catalyzed efficient one-pot synthesis of 2-pyrrolo-3′-yloxindoles

An InCl₃-catalyzed one-pot synthesis of 2-pyrrolo-3′-yloxindoles was achieved via three-component reaction of 3-phenacylideneoxindole, β-keto ester, and ammonium acetate at reflux by a sequential Michael addition followed by Paal-Knorr condensation.     

Synthesis of new fluorescent 2-(2′,2″-bithienyl)-1,3-benzothiazoles

Bithienyl-1,3-benzothiazole derivatives were synthesised by reacting various 5-formyl-5′-alkoxy- or 5-formyl-5′-N,N-dialkylamino-2,2′-bithiophenes with ortho-aminobenzenethiol in good to excellent yields. Evaluation of the fluorescence properties of these compounds was carried out. They show strong fluorescence in the 450-600 nm region, as well as high quantum yields and large Stokes’ shifts.     

Synthesis of 2′,3′-dideoxy-6′,6′-difluoro-3′-azanucleosides

The straightforward synthesis of four novel 2′,3′-dideoxy-6′,6′-difluoro-3′-azanucleosides 1a-d is described. Efficient construction of the fluorine-containing pyrrolidine ring through two different ways and installation of pyrimidine rings using the amino groups in the intermediates 12, 26 were the key steps of our synthesis.     

Synthesis and anti-HIV activities of phosphate triester derivatives of 3′-fluoro-2′,3′-dideoxythymidine and 3′-azido-2′,3′-dideoxythymidine

Fatty acyl-glycol phosphate triester conjugates of 3′-fluoro-2′,3′-dideoxythymidine (FLT) were prepared in three steps from the reaction of diisopropylphoramidous dichloride with fatty acyl-substituted glycols, followed by a coupling reaction with FLT and oxidation with tert-butyl hydroperoxide (t-BuOOH). Additionally, a number of fatty alcohols were reacted with diisopropylphoramidous dichloride to produce the phosphitylating intermediates, which underwent coupling reactions with 3′-azido-2′,3′-dideoxythymidine (AZT) and FLT followed by oxidation with t-BuOOH to yield fatty alcohol phosphate triester derivatives of AZT and FLT.     

Concise and efficient synthesis of 3′-O-triphosphates of 2′-deoxyadenosine and 2′-deoxycytidine

We describe concise and efficient synthesis of 2′-deoxyadenosine-3′-O-triphosphate (2′-d-3′-ATP) and 2′-deoxycytidine-3′-O-triphosphate (2′-d-3′-CTP) which are well known for their various biological applications. One-pot synthetic methodology was used to convert N⁶-Benzoyl-5′-O-levulinoyl-2′-deoxyadenosine into N⁶-Benzoyl-5′-O-levulinoyl-2′-deoxyadenosine-3′-O-triphosphate in 72% yield. One-step concurrent deprotection of N⁶-Benzoyl and 5′-O-levulinoyl groups using concentrated aqueous ammonia resulted in 2′-d-3′-ATP in 75% yield. The same synthetic strategy was successfully employed to convert N⁴-Benzoyl-5′-O-levulinoyl-2′-deoxycytidine into 2′-d-3′-CTP in 66% yield.     

Synthesis of dihydropyrazolo[3′,4′:3,4]pyrrolo[1,2-a]indoles and spiro-[3H-indole-3,3′-[Δ-1,2,4]-triazolin]-2-ones via intra and intermolecular 1,3-dipolar cycloadditions

A new class of dihydropyrazolo[3′,4′:3,4]pyrrolo[1,2-a]indoles and spiro[3H-indole-3,3′-[Δ²-1,2,4]-triazoline]-2-ones were synthesised via intra and intermolecular 1,3-dipolar cycloaddition reactions in good yields.     

Highly diastereoselective synthesis of spiro[cyclopropane-1,3′-indolin]-2′-ones via catalyst-free cyclopropanation using ethyl diazoacetate

Substituted 3-methyleneindolin-2-ones were efficiently cyclopropanated with ethyl diazoacetate to yield spiro[cyclopropane-1,3′-indolin]-2′-ones in a catalyst-free and highly diastereoselective reaction in a mixture of ethanol–acetonitrile (1:1 v/v) as solvent.     

Synthesis of 4′-aryl-2′,3′-dideoxynucleoside analogues

A series of 4′-aryl-2′,3′-dideoxynucleoside analogues were synthesized from optically pure 5-oxo-2-aryl-tetrahydrofuran-2-carboxylic acids up to 62% overall yield. 5-Oxo-2-aryl-tetrahydrofuran-2-carboxylic acids were obtained from 2-hydroxy-3-arylcyclopent-2-en-1-ones by asymmetric oxidation in up to 38-57% yield.     

Synthesis of (3′R,5′S)-3′-hydroxycotinine using 1,3-dipolar cycloaddition of a nitrone

To synthesize (3′R,5′S)-3′-hydroxycotinine [(+)-1], the main metabolite of nicotine (2), cycloaddition of C-(3-pyridyl)nitrones 3a, 3c, and 15 with (2R)- and (2S)-N-(acryloyl)bornane-10,2-sultam [(2R)- and (2S)-8] was examined. Among them, l-gulose-derived nitrone 15 underwent stereoselective cycloaddition with (2S)-8 to afford cycloadduct 16, which was elaborated to (+)-1.     

Diastereoselective synthesis of 1-alkyl-2,4,6-trioxoperhydropyrimidine-5-spiro-3′-(1′,2′,3′,4′-tetrahydroquinolines)

Knoevenagel products formed by the condensation of N-monoalkyl barbituric acids with o-tert-amino benzaldehydes undergo tert-amino effect reactions (T-reactions) yielding 1-alkyl-2,4,6-trioxoperhydropyrimidine-5-spiro-3′-(1′,2′,3′,4′-tetrahydroquinoline) derivatives as a mixture of (S^∗,S^∗)- and (S^∗,R^∗)-diastereomers. Mostly, the major diastereomer has the S^∗,S^∗-configuration. According to X-ray diffraction data in the solid form and NOE data in solution, diastereoselectivity of the T-reactions can be associated with the structure of the Knoevenagel products whose conformation is fixed by the strong intramolecular C-H?π interaction.     

1,2-二[3-(6,8-二叔丁基-3,4-二氢-1,3-苯并嗪)基]乙烷的合成及晶体结构

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Synthesis of a series of novel 2′,3′-dideoxy-6′,6′-difluoro-3′-thionucleosides

A series of novel 2′,3′-dideoxy-6′,6′-difluoro-3′-thionucleosides 1a-d, analogues of 3TC that has high biological activities against HIV and HBV, have been synthesized from the gem-difluorohomoallyl amine 7 in a straightforward fashion. Our synthesis featured the construction of thiofuranose skeleton through ring closure of key intermediates and installation of pyrimidine ring with amino group in compounds 13a,b.     

Synthesis of aliphatic 1,2-bishydroxylamines from 1,3- dihydroxyimidazolidines.

Reduction of l-hydroxy-3-imidazoline-3-oxides with NaBH₄ gives 1,3-dihydroxyimidazolidines. The latter on subsequent treatment with NH₂OH · HCl in EtOH or in hydrochloric acid afford 1,2-bishydroxylamines. An X-ray study of 1,2-bishydroxylaminocycloalkanes has shown them to becis-configurated.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 896–901, May, 1993.