Pyrrolopyrimidine nucleosides II. the total synthesis of 7-β-D-ribofuranosylpyrrolo[2,3-d]pyrimidines related to toyocamycin

The first synthesis of a 7-β-D-ribofuranosylpyrrolo[2,3-d]pyrimidine by direct ribosidation of a preformed pyrrolo[2,3-d]pyrimidine has now been accomplished via the fusion procedure. Subsequent functional group transformations furnished the 6-methyl-thio derivative of the nucleoside antibiotic toyocamycin. Preparation of the 1-, 3- and 7-methyl isomers of 4-amino-5-cyano-6-methylthiopyrrolo[2,3-d]pyrimidine was accomplished and has provided an unequivocal assignment for the actual site of ribosidation by a comparison of ultraviolet absorption spectra. Factors utilized for the assignment of anomeric configuration are discussed.     

Pyrrolopyrimidine nucleosides. IV. The synthesis of certain 4,5-disubstituted-7-(β-d-ribofuranosyl)pyrrolo[2,3-d]pyrimidines related to the pyrrolo[2,3-d]pyrimidine nucleoside antibiotics

The treatment of 4-chloro-7-(2′,3′,5′-tri-O-acetyl-β-D-ribofuranosyl)pyrrolo[2,3-d]pyrimidine ( 4 ) with N-bromoacetamide in methylene chloride has furnished the 5-bromo derivative of 4 which on subsequent deacetylation provided a good yield of 5-bromo-4-chloro-7-(β-D-ribo-furanosyl)pyrrolo[2,3-d] pyrimidine ( 6 ). Assignment of the halogen substituent to position 5 was made on the basis of pmr studies. Treatment of 6 with methanolic ammonia afforded 4-amino-5-bromo-7-(β-D-ribofuranosyl)pyrrolo[2,3-d ]pyrimidine ( 8 , 5-bromotubercidin) and a subsequent study has revealed that the 4-chloro group of 6 was replaced preferentially in a series of nucleophilic displacement reactions. The analogous synthesis of 4,5-dichloro-7-(β-D-ribo-furanosyl)pyrrolo[2,3-d]pyrimidine ( 13b ) and 4-chloro-5-iodo-7-(β-D-ribofuranosyl)pyrrolo[2,3-d]pyrimidine ( 13a ) from 4 furnished 5-chlorotubercidin ( 15 ) and 5-iodotubercidin ( 14 ), respectively, on treatment of 13b and 13a with methanolic ammonia. The possible biochemical significance of these tubercidin derivatives is discussed.     

Pyrrolopyrimidine nucleosides. XIII. Synthesis and chemical reactivity of certain selenopyrrolo[2,3-d]pyrimidine nucleosides

5-Cyano-7-(β-D-ribofuranosyl)pyrrolo[2,3-d]pyrimidin-4-selone ( 1 ) has been prepared via a reaction of the appropriate 4-chloro compound with sodium hydrogen selenide. Alkylation of 2 under basic conditions has provided certain 4-substitutedseleno-5-cyano-7-(β-D-ribofuranosyl)-pyrrolo[2,3-d]pyrimidines. 5-Cyano-4-methylseleno-7-(β-D-ribofuranosyl)pyrrolo[2,3-d]pyrimidine was allowed to react with hydroxylamine and hydrazine. The products obtained and reaction course were compared to those obtained from identical reactions using the corresponding sulfur analog.     

An expedient microwave-assisted, solvent-free, solid-supported synthesis of pyrrolo[2,3-d]pyrimidine-pyrano[5,6-c]coumarin/[6,5-c]chromone derivatives by intramolecular hetero Diels-Alder reaction

A rapid synthesis of pyrrolo[2,3-d]pyrimidine annulated pyrano[5,6-c]coumarin/[6,5-c]chromone derivatives has been accomplished in good yields via an intramolecular domino hetero Diels-Alder reaction using microwave irradiation under solvent-free, solid-supported conditions.     

Synthesis of new thiazolo[2,3-b]pyrimidine derivatives of pharmaceutical interest

2H-5-Amino-6-cyano-3,7-dioxothiazolo[2,3-b]pyrimidine was subjected to ring formation affording thiazolo[2,3-b]pyrimidine derivatives. 2H-5-Amino-6-cyano-3,7-dioxo-2-phenylmethylenethiazolo[2,3-b]pyrimidine was also subjected to ring formation affording pyrimido[4,5-d]-, pyrano[2,3-d]-, and pyrido[2,3-d]thiazolo[2,3-b]pyrimidine derivatives. 2-Anilinothiocarbonyl-3,9-dioxo-8-imino-7-phenyl-6-thioxothiazolo[2,3-b]pyrimido[4,5-d]pyrimidine and 8-amino-3,9-dioxo-6-thioxothiazolo[2,3-b]pyrimido[4,5-d]pyrimidine reacted with α-haloactive-methylene compounds to afford heterocyclic compounds containing two, fused and isolated, thiazole moieties, respectively.     

Palladium-catalyzed reductive N-heterocyclization of alkenyl-substituted nitroarenes as a viable method for the preparation of bicyclic pyrrolo-fused heteroaromatic compounds

Palladium-catalyzed, carbon monoxide-mediated reductive N-heterocyclization of nitro-heteroaromatic compounds having an alkene adjacent to the nitro-group affords bicyclic pyrrolo-fused heteroaromatic molecules. This type of reaction was used to prepare the fused bicyclo[3.3.0] ring-system: thieno[3,2-b]pyrrole, thieno[2,3-b]pyrrole, furo[2,3-b]pyrrole, pyrrolo[3,2-d]thiazole, and pyrrolo[2,3-d]imidazole and the bicyclo[4.3.0] ring-systems: pyrrolo[3,2-b]pyridine, pyrrolo[2,3-b]pyridine, pyrrolo[3,2-c]pyridine, pyrrolo[2,3-c]pyridine, pyrrolo[3,2-c]pyridazine, and pyrrolo[3,2-d]pyrimidine in 32-94% yield.     

Synthesis and photophysical properties of oligoarylenes with a pyrrolo[2,3-d]pyrimidine core

The palladium-catalyzed Suzuki-Miyaura reaction of 2,4-dichloropyrrolo[2,3-d]pyrimidine with aryl boronic acids has been studied. Pd(OAc)₂/dicyclohexyl(2-biphenyl)phosphine/K₃PO₄ was found to be an efficient catalyst system to prepare 4-aryl-2-chloro- and 2,4-diarylpyrrolo[2,3-d]pyrimidines. Novel non-linear molecules consisting of a pyrrolo[2,3-d]pyrimidine core and aryl branches have been elucidated as blue light-emitters with fluorescence quantum yields ranging from 4% to 67% in THF solution. The impact of an electron-withdrawing t-BuOCO group attached to the pyrrole ring of pyrrolopyrimidine derivatives on optical properties is discussed.     

Novel pyrrolo[2,3-d]pyrimidine derivatives: Design,synthesis, structure elucidation and in vitro anti-BVDV activity

The progression of drug resistance of viral infection justifies the discovering of new anti-viral agents. Thus, a novel series of pyrrolopyrimidine derivatives 5–7 and 9–18 were designed, synthesized and fully characterized by IR, mass spectroscopy, NMR, and elemental analysis. The structure of 4,6-dichloro-pyrrolo[2,3-d]pyrimidine 10 elucidated by single crystal X-ray diffraction. Herein, we reported the first pyrrolo[2,3-d]pyrimidine compounds with trichloromethane at position 2 of the pyrimidine ring. As initial biological activity screening, evaluation of the pyrrolo[2,3-d]pyrimidine compounds as anti-BVDV (Bovine Viral Diarrhea Virus) was examined. The compounds 11, 13, 16 and 17 exhibited excellent activity as a potent inhibitor against BVDV. Structure activity relationship showed that the pyrrolo[2,3-d]pyrimidine molecules presenting hydrogen atom or trichloromethyl group on C2 and chlorine, sulfur, pyrrolidine or methoxy groups on C4 of the pyrimidine ring showed high activity as anti-BVDV in comparison with the compounds which have Cl or CH₃ on C2 position.     

Synthesis and Ring Transformation of Pyrrolo[2,3-d][1,3]oxazine to Pyrrolo[2,3-d]Pyrimidines

A convenient route is reported for the synthesis of fused pyrrolo[2,3-d][1,3]oxazine and pyrrolo[2,3-d]-pyrimidine derivatives from 2-amino-1-benzyl-3-t-butoxycarbonyl]-4,5-dimethylpyrrole.     

A study of electrophilic substitution in the pyrrolo[2,3-d]pyrimidine ring

Several 4,5-disubstituted pyrrolo[2,3-d ]pyrimidines were prepared for the first time via electrophilic substitution, e.g. halogenation, nitration and sulfonation. PMR data for certain pyrrolo[2,3-d]pyrimidines are included which has furnished conclusive evidence that electrophilic substitution occurred at position 5. These pyrrolo[2,3-d]pyrimidines, with electron -withdrawing substituents at position 5, are of considerable interest as bases for the preparation of nucleoside derivatives related to tubercidin, toyocamcin and sangivamycin.     

Design,synthesis, and toward a side-ring optimization of tricyclic thieno[2,3-d]pyrimidin-4(3H)-ones and their effect on melanin synthesis in murine B16 cells

Abstract

Herein, we report the synthesis of 48 novel 3-sulfonylamides containing a tricyclic thieno[2,3-d]pyrimidin-4(3H)-one moiety, and their influence on melanin synthesis in murine B16 cells. All target sulfonylamides were synthesized through key intermediate 3-nitro-thieno[2,3-d]pyrimidin-4(3H)-ones using three types of ipso-nitration reactions. In this case, we converted the pyrido[1,2-a]- fragment of the thieno[2,3-d]pyrimidine moiety to pyrrolo[1,2-a]- and azepino[1,2-a]- side-rings in order to evaluate the bioactivities of the synthesized derivatives for a structure activity-relationships point of view. The obtained results suggest that some of the selected compounds revealed a promising influence on melanin synthesis in murine B16 cells and may serve as lead compounds for further drug discovery and development.     

The reactions of heterocyclic isothiocyanates bearing an ortho ester group with aminoalcohols

Heterocyclic isothiocyanates 1,5,9 , bearing an o-ester group were converted to thiourea derivatives 2a-c, 6a-b , and 10a-b , respectively, using β-aminoalcohols, and to the fused ring systems, e.g., thieno[3,2-d]pyrimidine 4a-b , pyrido[2,3-d]pyrimidine 8 , pteridine 11a , thiazolo[3,2-a]pyrido[2,3-d]pyrimidine 7a-b , and thiazolo[3,2-a]mieno[3,2-d]pyrirnidine 3a-c , derivatives.     

Synthesis of certain alkenyl purines and purine analogs

Synthesis of alkenyl derivatives of certain purines and purine analogs is described. Direct alkylation of the sodium salt of 6-chloropurine (1) either with 1-bromo-2-pentene or 4-bromo-2-methyl-2-butene in N,N-dimethylformamide furnished N-7, 4a and N-9, 3a , 3b alkenyl derivatives. Similar alkylation of 2-amino-6-chloropurine (2) provided the corresponding N-7, 4c-4e and N-9, 3c-3e alkenyl derivatives. Acid hydrolysis of these chloro derivatives 3a-3e, 4a,c-e furnished the corresponding alkenyl hypoxan-thines 6a, 6b and 7a or alkenyl guanines 6c-6e and 7c-7e. Treatment of 3a-3d with thiourea in absolute ethanol provided the corresponding 6-thio derivatives 5a-5d. Alkylation of the sodium salt of either purine-6-carboxamide (8) or 1,2,4-triazole-3-carboxamide (10) gave mainly one isomer 9a, 9b and 11a, 11b. The direct alkylation of pyrrolo[2,3-d]pyrimidin-4(3H)-one (12) gave N-3 alkenyl derivatives 13a, 13b , and the N-7 alkenyl derivatives 16a, 16b have been prepared starting from the 4-chloro derivative 14 . Synthesis of 2-amino-7-(2-penten-1-yl)pyrrolo[2,3-d]pyrimidin-4(3H)-one (19a) has been accomplished starting from 2-amino-4-methoxypyrrolo[2,3-d]pyrimidine (17) . These alkenyl derivatives were found to be devoid of anti-HCMV activity in vitro.     

Indium chloride catalyzed intramolecular cyclization of N-aryl imines: synthesis of pyrrolo[2,3-d]pyrimidine annulated tetrahydroquinoline derivatives

The intramolecular aza Diels-Alder cyclization reaction of aldimines derived from aromatic amines and N-prenyl/cinnamyl derivatives of pyrrolo[2,3-d]pyrimidine were efficiently catalyzed by InCl₃ to afford the corresponding tetrahydroquinoline derivatives in good yields.     

Annelated piperazinyl-7,8-dihydro-6H-thiopyrano[3,2-d]pyrimidines

Tricyclic analogs of piperazinylthiopyrano[3,2-d]pyrimidine hypoglycemic agents were prepared. The angular tricyclic systems, 8,9-dihydro-7H-thiopyrano[2,3-e][1,2,4]triazolo[4,3-a]pyrimidine and 8,9-dihydro-7H-tetrazolo[1,5-a]thiopyrano[2,3-e]pyrimidine derivatives were synthesized from 2,4-dichloro-7,8-dihydro-6H-thiopyrano[3,2-d]pyrimidine in three step sequences. Derivatives of the linear tricyclic system, 5,6-dihydro-7H-thiopyrano[3,2-d][1,2,4]triazolo[2,3-a]pyrimidine, were prepared by condensation of 3-amino-1,2,4-triazole with ethyl 3-oxo-tetrahydropyran-2-carboxylate. The tricyclic heteroaryl-piperazines lacked significant hypoglycemic activity.     

Synthesis and Properties of 6-Amino-7-hetaryl-5-R-5H-pyrrolo[2,3-b]pyrazine-2,3-dicarbonitriles

We have established that when 5-chloro-6-[cyano(2,3-dihydro-1-R-benzo[d]azol-2-yl)methyl]-2,3-pyrazinedicarbonitriles are reacted with nucleophilic reagents (aliphatic and aromatic amines, hydrogen sulfide), annelation of the five-membered ring occurs on the [b] face of the pyrazine with formation of 6-amino-7-hetaryl-5-R-5H-pyrrolo[2,3-b]pyrazine-2,3-dicarbonitriles and 6-amino-7-(1H-benzo[d]imidazol-2-yl)thieno[2,3-b]pyrazine-2,3-dicarbonitrile respectively. Further heating with excess of acylating reagent leads to formation of a novel heterocyclic system 1H-benzo[4,5]imidazo[1,2-c]pyrazino[2',3':4,5]pyrrolo[3,2-e]pyrimidine. Reaction of vicinal dinitriles with hydrazine hydrate leads to the novel system 1H-pyrrolo[2',3':5,6]pyrazino[2,3-d]pyridazine.     

Synthesis,design, and antimicrobial activity of pyrido[2,3-d][1,2,4]triazolo[4,3-a]pyrimidinones based on quinoline derivatives

The pyrido[2,3-d]pyrimidine moieties are one of the most biologically widespread heterocyclic compounds as antimicrobial, antioxidant, antitubercular, antiviral and anti-inflammatory. Hence, we synthesized an efficient new series of 2-thioxo-pyrido[2,3-d]pyrimidinone, 2-hydrazinyl-(quinolin-2-yl)pyrido[2,3-d]pyrimidinone,N′-(quinolin-2-yl)-pyrido[2,3-d]pyrimidine-(formo/aceto)-hydrazide and substituted-(quinolin-2-yl)pyrido[2,3-d][1,2,4]triazolo[4,3-a]pyrimidinone derivatives. The characterization of new compounds was corresponded by using spectroscopic techniques, IR, NMR and Mass spectra. In vitro, all compounds were evaluated as antimicrobial activity compared with cefotaxime sodium and nystatin as the standard drug. This work deals with the exploration of the new heterocyclic compounds and medicinal diversity of quinoline-pyrido[2,3-d][1,2,4]triazolo[4,3-a]pyrimidine derivatives that might pave the way for long in the discovery of therapeutic medicine for future drug design.     

New Facile Route to Synthesize Furo[3,2-e][1,2,4]triazolo[4,3-c]pyrimidine and Furo[3,2-e][1,2,4]triazolo[1,5-c]pyrimidine Derivatives

A new facile route for synthesis of 3-(aryl)-8,9-diphenylfuro[3,2-e][1,2,4]triazolo pyrimidines derivative from the same starting material, 2-amino-4,5-diphenylfuran-3-carbonitrile, has been developed through heterocyclization of the corresponding arylidene-hydrazono-5,6-diphenylfuro[2,3-d]pyrimidine and N-(arylmethylene)-4-imino-5,6-diphenylfuro[2,3-d]pyrimidin-3(4H)-amine under refluxing condition with acetic anhydride followed by air oxidation. The products were obtained in good yield with an easy workup along with the purification of products by a nonchromatographic method. This general synthetic procedure can be extended to the preparation of a wide range of isomeric triazoles using 2-amino 3-carbonitrile bifunctional derivatives.     

Synthesis of condensed tricyclic pyrazolo[3,4-b]thieno[2,3-d]pyridine and related isostere derivatives

In this paper we report the synthesis of an isosteric series of new heterotricyclic derivatives, corresponding to pyrazolo[3,4-b]thieno[2,3-d]pyridine ( 1 ), pyrazolo[3,4-b]furano[2,3-d]pyridine ( 2 ) and pyrazolo[3,4-b]pyrrolo[2,3-d]pyridine ( 3 ). These functionalized compounds were obtained, in high overall yield, by an ‘one-pot’ reaction of the chloroester intermediate 4 , possessing the pyrazolo[3,4-b]pyridine system, with an adequate α-hetero-acetyl ester derivative, in SNAr/Dieckman cyclization type consecutive reactions.