Deazapurine solid-phase synthesis: combinatorial synthesis of a library of N3,N5,C6-trisubstituted pyrrolo[3,2-d]pyrimidine derivatives on cross-linked polystyrene bearing a cysteamine linker

Solid-phase methodology for the preparation of pyrrolo[3,2-d]pyrimidine-6-carboxylates with diversity at the N3 pyrmidine nitrogen has now been elaborated to allow for the generation of pyrrolopyrimidine libraries with members possessing diversity at the N3, N5, and C6 positions. The diversification of the N5 position was achieved by treating the parent resin-bound pyrrolo[3,2-d]pyrimidines 3 with an alkyl halide in the presence of Cs2CO3 in DMF. Modification of the C6 carboxylate of resin-bound pyrrolopyrimidines 3-5 was first achieved by hydrolysis of the benzyl ester using LiOH in a mixture of THF/H2O/MeOH. Further alteration of the C6 position of resin-bound pyrrolo[3,2-d]pyrimidine-6-carboxylic acids 6-8 was then performed by activation with triphosgene and treatment with an amine to furnish resin-bound pyrrolo[3,2-d]pyrimidine-6-amides. Twenty-two pyrrolo[3,2-d]pyrimidines 1a-v with different substituents at the N3, N5, and C6 positions were obtained in yields of 21-83% and purities of 61-98% after cleavage from the solid support.     

Diversity-oriented synthesis of functionalized pyrrolo[3,2-d]pyrimidines with variation of the pyrimidine ring nitrogen substituents

Nine 2,4-dioxo-2,3,4,5-tetrahydro-1H-pyrrolo[3,2-d]pyrimidine-6-carboxylic acid benzyl esters 12 were synthesized in four steps from 4-oxo-N-(PhF)proline benzyl ester 7 by a general method in which elements of molecular diversity were readily added onto the pyrimidine nitrogens. Conversion of 4-oxoproline 7 into the corresponding aminopyrrole 8 using benzyl-, allyl-, and isopropylamine followed by treatment with phenyl, allyl, and ethyl isocyanate gave nine different ureas 9. 4-Ureido-1H-pyrrole-2-carboxylic acid benzyl esters 9 were then converted into the respective pyrrolo[3,2-d]pyrimidines 12 using trichloroacetyl chloride in acetonitrile followed by treatment with Cs(2)CO(3). Crystallization from toluene gave the desired deazapurines in 37-55% overall yield from proline 7.     

2-vinylpyrroles and pyrrolo[3,2-d]pyrimidines from direct addition of aldehydes to 4-amino-pyrrole-2-carboxylate derivatives

A new methodology for the direct preparation of 2-vinylpyrroles is presented. Treatment of 4-amino-pyrrole-2-carboxylates 5a-c and 6a-d with aliphatic aldehydes and TFA furnished 2-vinylpyrroles 2a-k in 9-87% yields. Under similar conditions ureidopyrroles 5a-c reacted with aryl aldehydes to provide pyrrolo[3,2-d]pyrimidines 1a-d in 28-63% yields.     

Traceless solid-phase synthesis of bicyclic dihydropyrimidones using multidirectional cyclization cleavage

Solid-phase and solution-phase protocols for the synthesis of furo[3,4-d]pyrimidines, pyrrolo[3,4-d]pyrimidines, and pyrimido[4,5-d]pyridazines are reported. The multistep solid-phase sequence involves the initial high-speed, microwave-promoted acetoacetylation of hydroxymethylpolystyrene resin with methyl 4-chloroacetoacetate. The immobilized 4-chloroacetoacetate precursor was subsequently subjected to three-component Biginelli-type condensations employing urea and a variety of aromatic aldehydes. The resulting 6-chloromethyl-functionalized resin-bound dihydropyrimidones served as common chemical platforms for the generation of the desired heterobicyclic scaffolds using three different traceless cyclative cleavage strategies. The corresponding furo[3,4-d]pyrimidines were obtained by microwave flash heating in a rapid, thermally triggered, cyclative release. Treatment of the chloromethyl dihydropyrimidone intermediates with a variety of primary amines followed by high-temperature microwave heating furnished the anticipated pyrrolo[3,4-d]pyrimidine scaffolds via nucleophilic cyclative cleavage. In a similar way, reaction with monosubstituted hydrazines resulted in the formation of pyrimido[4,5-d]pyridazines. All compounds were obtained in moderate to good overall yields and purities.     

Pyrrolo[3,2-e][1,4]diazepin-2-one synthesis: a head-to-head comparison of soluble versus insoluble supports

Aryldiazepin-2-ones are known as "privileged structures", because they bind to multiple receptor types with high affinity. Toward the development of a novel class of aryldiazepin-2-one scaffolds, the synthesis of pyrrolo[3,2-e][1,4]diazepin-2-ones on a support was explored starting from N-(PhF)-4-hydroxyproline and featuring an acid-catalyzed Pictet-Spengler reaction to form the diazepine ring. Three supports [Wang resin, tetraarylphosphonium (TAP) soluble support, and Merrifield resin] were examined in the synthesis of the heterocycle and exhibited different advantages and disadvantages. Wang resin proved effective for exploratory optimization of the synthesis by identification of intermediates after resin cleavage under mild conditions; however, the acidic conditions of the Pictet-Spengler reaction caused premature loss of resin-bound material. Direct monitoring of reactions by TLC, RP-HPLC-MS, and in certain cases NMR spectroscopy was possible with the TAP support, which facilitated purification of intermediates by precipitation; however, incomplete precipitation of material led to overall yields lower than those from solid-phase approaches on resin. Merrifield resin proved stable to the conditions for the synthesis of the pyrrolo[3,2-e][1,4]diazepin-2-one targets and would be amenable to "split-and-mix" chemistry; however, relatively harsh conditions were necessary for final product cleavage. Perspective for the application of different solid-phase approaches in heterocycle library synthesis was thus obtained by demonstration of the respective utility of the three supports for preparation of pyrrolo[3,2-e][1,4]diazepin-2-one.     

Solid-phase synthesis of tetrasubstituted pyrrolo[2,3-d]pyrimidines

A facile solid phase synthesis of 2,4,6,7-tetrasubstituted pyrrolo[2,3-d]pyrimidines is described. The synthesis involves a highly efficient five-step route starting from resin-bound dimeric peptoids. To demonstrate the versatility of our method, a representative library of 108 tetrasubstituted pyrrolo[2,3-d]pyrimidines of high quality was synthesized.     

Synthèse des pyrido[2,3-d] el [3,2-d] -s-triazolo[3,4-f] pyrimidines el de (pyrazolyl-1')-4 pyrido[2,3-d] et [3,2-d] pyrimidines

The synthesis of two new heterocycles is described: pyrido-[2,3-d]-.s-triazolo[ 3,4-f] pyrimidine and pyrido[3,2-d]-.s-triayzolo-[3,4-f] pyrimidine. 4-[I'-Pyrazolyl]pyrido[2,3-d]pyrimidines and 4-[1′-pyrazoly1] pyrido[ 3,2-d] pyrimidine are obtained by the action of 4-hydrazinopyrido[2,3-d]pyrimidine and 4-hydrazinopyrido-[3,2-d]pyrimidine with several β-diketones.     

Aromaticity in heterocyclic systems V. Bromination studies of certain purines,pyrrolo[3,2-d]pyrimidines and pyrazolo[4,3-d]pyrimidines

The bromination of certain selected purines, pyrrolo[3,2-d]pyrimidines and pyrazolo[4,3-d]-pyrimidines has been studied and the reactivity of these systems compared. Displacement of a carboxyl group by bromine was noted in the case of 6-carboxypyrrolo[3,2-d]-2,4-pyrimidinedione. In contrast to xanthine, 2,6-diethoxypurine readily brominated at position 8. Pyrazolo-[4,3-d]-7-pyrimidone was readily brominated at position 3.     

Solid-phase synthesis of 3-aminopyrrole-2,5-dicarboxylate analogues

An efficient strategy has been developed for the solid-phase parallel synthesis of 3-aminopyrrole-2,5-dicarboxylate analogues. A library of twenty-nine 2,3,5-trisubstituted pyrroles has been synthesized on Wang resin by a 5-6 step process. The attachment of (2S,4R)-4-hydroxy-N-(PhF)proline cesium salt (PhF = 9-(9-phenylfluorenyl)) to Wang bromide resin, followed by alcohol oxidation, produced the resin-bound 4-oxo-N-(PhF)prolinate as the pyrrole precursor. Resin-bound 3-aminopyrroles were synthesized by treatment of the oxo-N-(PhF)prolinate resin with different secondary amines and diversified at the 2-position by acylation with trichloroacetyl chloride and haloform reactions with primary amines. 3-Aminopyrrole-2,5-dicarboxylates were isolated in 81-99% purity and 51-99% yields after cleavage from the resin using TFA or sodium methoxide.     

含哌嗪基7-溴噻吩并[3,2-d]嘧啶抗癌试剂的设计与合成

为寻找以蛋白酪氨酸激酶为靶点的新型抗癌试剂,本文设计与合成了系列含哌嗪基的7-溴噻吩并[3,2-d]嘧啶衍生物。以巯基乙酸为原料,经六步反应得4-氯-7-溴噻吩并[3,2-d]嘧啶母核,再与不同的哌嗪衍生物在添加三乙胺作碱的条件下反应,制备了五个未见报道的含哌嗪基7-溴噻吩并[3,2-d]嘧啶化合物。结构经1H NMR和HRMS表征。     

Synthesis of 1,2,4-triazolo[4,3-c]-, tetrazolo[1,5-c]-, and 1,2,4-triazino[5,6-c]pyrano[4'3':4,5]pyrrolo-[3,2-e]pyrimidine derivatives

4-Hydrazinopyrano[4',3':4,5]pyrrolo[2,3-d]pyrimidines served as precursors in the synthesis of new heterocyclic systems, namely, 1,2,4-triazolo[4,3-c]-, tetrazolo[1,5-c]-, and 1,2,4-triazino[5,6-c] pyrano[4',3':4,5]-pyrrolo[3,2-e]pyrimidines.A. L. Mndzhoyan Institute of Fine Organic Chemistry, National Academy of Sciences of the Republic of Armenia, 375014 Yerevan. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 700-703, May, 1995. Original article submitted January 10, 1995; revision submitted April 20, 1995.     

Multistep, microwave assisted, solvent free synthesis and antibacterial activity of 6-substituted-2,3,4-trihydropyrimido[1,2-c]9,10,11,12-tetrahydrobenzo[b]thieno[3,2-e]pyrimidines

A novel, efficient, microwave assisted route for the synthesis of 6-substituted-2,3,4-trihydropyrimido[1,2-c]-9,10,11,12-tetrahydrobenzo[b]thieno[3,2-e]pyrimidines in good yields has been developed. The intermediates, 2-substituted-4-[3-hydroxy(propyl-1-amino)]5,6,7,8-tetrahydrobenzo[b]thieno[2,3-d]pyrimidines were obtained by irradiating 2-substituted-4-chloro-5,6,7,8-tetrahydrobenzo[b]thieno[2,3-d]pyrimidines with 1-amino-propanol under basic conditions in a microwave oven. 4-Chlorothieno[2,3-d]pyrimidines were synthesized by microwave irradiation of equimolar mixture of 4-hydroxythieno[2,3-d]pyrimidines and phosphorus oxychloride. The final compounds were screened for antibacterial activity by Kirby Bauer's method using amicacin as the standard against various gram positive and gram negative bacteria. All the compounds showed antibacterial activity comparable with the standard.     

Synthesis of Novel Pyrrylthieno[2,3-d]Pyrimidines and Related Pyrrolo[1″,2″:1″,6″]Pyrazino[2″,3″:4,5]Thieno[2,3-d]Pyrimidines

4-Methyl-2-phenyl-5-(1-pyrryl)-6-substituted-thieno[2,3-d]pyrimidines ( 3a-c , 4a-c , 5a , b , and 6 ) have been synthesized. Some of the substituents in position 6 were used to build up different sulfur-, nitrogen- and/or oxygen-containing heterocyclic rings at that position. The 4-methyl-2-phenyl-5-(1-pyrryl)-thieno[2,3-d]pyrimidine-6-carboazide ( 20 ) was also used as a key intermediate in the synthesis of the target pyrrolo[1",2":1',6']pyrazino[2',3':4,5]thieno[2,3-d]pyrimidines.     

Synthesis of a 2, 4, 8-trisubstituted pyrimidino[5, 4-d]pyrimidine library via sequential SNAr reactions on solid-phase

A solid-phase synthesis of 2, 4, 8-substituted pyrimidino[5, 4-d]pyrimidines involving three controlled S(N)Ar reactions has been developed. Exploration of different heterocyclic starting materials and resin-bound intermediates is highlighted. The preferred method starts with the treatment of resin-bound anilines with 2, 4, 8-trichloropyrimidino[5, 4-d]pyrimidine. This intermediate is subsequently treated with various amines in two steps to yield the final products. The scope of each diversity step was determined and a library of 16, 000 compounds was synthesized.     

Reaction of 4-aminouracil with 2-(arylmethylene)indan-1, 3-diones

The reaction of the arylmethyleneindanones (I) with 4-aminouracil or its N-methyl derivative (IV) gives new multinuclear nitrogencontaining systems—5-aryl-2,4,6-trioxo-1-R-3-R-1,2,3,4,5,11-hexahydro-11-azafluoreno[3,2-d]pyrimidines (V), which are oxidized by chromic anhydride to 5-aryl-2,4,6-trioxo-1-R-3-R-1,2,3,4-tetrahydro-11-azafluoreno[3,2-d]pyrimidines (VI). The UV and IR spectra of the compounds synthesized are given.     

Torp-Ziegler Cyclization in the Synthesis of 3-Amino-4-cyanopyrrole Derivatives

Polyfunctional derivatives of 3-aminopyrrole have been synthesized from several substituted -enamino nitriles using Torp-Ziegler cyclization. These compounds are starting materials for further conversions, particularly for the synthesis of pyrrolo[3,2-d]- and pyrrolo[3,4-d]pyrimidines.     

Studies on Thiazolopyridines. Part 1: Antimicrobial Activity of Some Novel Fluorinated Thiazolo[3,2-a]Pyridines and Thiazolo[2′,3′:1,6]Pyrido[2,3-d]Pyrimidines

Ternary condensation of aromatic aldehydes, malononitrile and thioglycolic acid (2:2:1 molar ratio) in ethanol/piperidine afforded the corresponding thiazolo[3,2-a]pyridines 1a-d . Thiazolo[2',3':1,6]pyrido[2,3-d]pyrimidine 4 was obtained by refluxing of compound 1a with acetic anhydride. Also, thiazolopyrido pyrimidine 6 was produced by refluxing of 1a with triethylorthoformate followed by treatment with hydrazine hydrate. Refluxing 1a with formic acid yielded the thiazolopyridopyrimidine 8 which on chlorination with thionyl chloride furnished the chloro derivative 9 . Finally, amino thiazolo[2',3':1,6]pyrido[2,3-d]pyrimidine 10 was obtained by treatment of 1a with formamide. The structures of these compounds were established on the basis of elemental analyses, IR, 1 H NMR, and mass spectral data. Also, the antimicrobial activity of some synthesized compounds is reported.     

Synthesis of heterocyclic compounds possessing the 4H-thieno[3,2-b]pyrrole moiety

A series of novel heterocyclic combinatorial libraries containing 4H-thieno[3,2-b]pyrrole, thieno[2',3':4,5]-pyrrol[1,2-d][1,2,4]triazine and thieno[2',3':4,5]pyrrolo[1,2-a]pyrazine heterocyclic moieties were obtained by parallel solution-phase synthesis. Key steps include different reactions of initial alkyl 4H-thieno[3,2-b]-pyrrole-5-carboxylates, such as alkylation with alkylating agents; transformation of the carboxylate group into different reactive functionalities, followed by reactions with electrophilic species; intramolecular cyclizations; and amide bond formation. Simple manual techniques for parallel reactions were coupled with easy purification procedures to give high-purity final products.     

Synthesis and interconversion of isomeric pyrrolotriazolopyrimidines

4‐Hydrazino‐7H‐pyrrolo[2,3‐d]pyrimidines 4 were cyclocondensed with formic acid or triethyl orthoformate to give 7H‐pyrrolo[3,2‐e][1,2,4]triazolo[1,5‐c]pyrimidines 6 and 7H‐pyrrolo[3,2‐e][1,2,4]triazolo[4,3‐c]pyrimidines 7 , respectively. The [4,3‐c] isomers 7 were rearranged into thermodynamically more stable [1,5‐c] isomers 6 . The identical compounds 6 were prepared using another route by reacting 3‐amino‐4‐imino‐7H‐pyrrolo[2,3‐d]pyrimidines 3 with formic acid or triethyl orthoformate. The reaction of 2‐amino‐3‐cyanopyrroles 1 with triethyl orthoformate gave N‐ethoxymethylene‐2‐amino‐3‐cyanopyrroles 2 . Further reaction with an equivalent of hydrazine hydrate provided 3‐amino‐4‐imino‐7H‐pyrrolo[2,3‐d]pyrimidines 3 , whereas treatment with excess of hydrazine hydrate, 3 rearranged to 4‐hydrazino‐7H‐pyrrolo[2,3‐d]pyrimidines 4 . Compounds 4 were also obtained by the treatment of N‐ethoxymethylene‐2‐amino‐3‐cyanopyrroles 2 in excess of hydrazine hydrate. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:265–273, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20295     

Synthesis of new pyrrolo-[3,4-c]isoxazole, pyrrolo[2,3-d]-[1,2,3]triazole, triazolo[4,5-c]-pyridazine, and dipyrrolo-[3,2-b:3′,4′-d]pyran derivatives

New pyrrolo[3,4-c]isoxazole derivatives were synthesized from the key intermediates 4-cyanopyrrolidin-3-ones in two steps. Pyrrolo[2,3-d][1,2,3]triazoles and triazolo[4,5-c]pyridazine were obtained from 2-arylhydrazono-4-cyano-1-(4′-methoxyphenyl)-3-oxopyrrolidines by refluxing with phenylhydrazine in either ethanol or glacial acetic acid. Aldol self-condensation of 1-aryl-4-cyanopyrrolidin-3-ones afforded dipyrrolo-[3,2-b:3′, 4′-d]pyran derivatives. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1841–1848, December, 2007.