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71.
Nabih S. Girgis Roland K. Robins Howard B. Cottam 《Journal of heterocyclic chemistry》1990,27(2):171-175
Several N-5 ribofuranosyl-2,4-disubstituted pyrrolo[3,2-d]pyrimidine (9-deazapurine) nucleosides were prepared by the single phase sodium salt glycosylation of 2,4-dichloro-5H-pyrrolo[3,2-d]pyrimidine ( 3 ) using 1-chloro-2,3-O-isopropylidene-5-O-(t-butyl)dirnethylsilyl-α-D-ribofuranose ( 2 ). Use of 2 for the glycosylation avoided the formation of “orthoamide” products 1 and provided an excellent yield of the β nucleoside, 2,4-dichloro-5-[2,3-O-isopropylidene-5-O-(t-butyl)dimethylsilyl-β-D-ribofuranosyl]-5H-pyrrolo[3,2-d]pyrimidine ( 4 ), along with a small amount of the corresponding α anomer, 5 . Compound 4 served as the versatile intermediate from which the N-7 ribofuranosyl analogs of the naturally-occurring purine nucleosides adenosine, inosine and guanosine were synthesized. Thus, controlled amination of 4 followed by sugar deprotection and dehalogenation yielded the adenosine analog, 4-amino-5-β-D-ribofuranosyl-5H-pyrrolo[3,2-d]pyrimidine ( 8 ) as the hydrochloride salt. Base hydrolysis of 4 followed by deprotection gave the 2-chloroinosine analog, 10 , and subsequent dehalogenation provided the inosine analog, 5-β-D-ribofuranosyl-5H-pyrrolo[3,2-d]-pyrimidin-4(3H)-one ( 11 ). Amination of 10 furnished the guanosine analog, 2-amino-5-β-D-ribofuranosyl-5H-pyrrolo[3,2-d]pyrimidin-4(3H)-one ( 12 ). Finally, the α anomer in the guanosine series, 16 , was prepared from 5 by the same procedure as that used to prepare 12 . The structural assignments were made on the basis of ultraviolet and proton nmr spectroscopy. In particular, the isopropylidene intermediates 9 and 14 were used to assign the proper configuration as β and α, respectively, according to Imbach's rule. 相似文献
72.
Jack D. Anderson Howard B. Cottam Steven B. Larson L. Dee Nord Ganapathi R. Revankar Roland K. Robins 《Journal of heterocyclic chemistry》1990,27(2):439-453
Synthesis of the pyrazolo[3,4-d]pyrimidin-3-one congeners of guanosine, adenosine and inosine is described. Glycosylation of 3-methoxy-6-methylthio-1H-pyrazolo[3,4-d]pyrimidin-4(5H)-one ( 13 ) with 1-O-acetyl-2,3,5-tri-O-benzoyl-D-ribofuranose ( 16 ) in the presence of boron trifluoride etherate gave 3-methoxy-6-methylthio-1-(2,3,5-tri-O-benzoyl-β-D-ribofuranosyl)pyrazolo[3,4-d]pyrimidin-4(5H)-one ( 17 ) which, after successive treatments with 3-chloroperoxybenzoic acid and methanolic ammonia, afforded 6-amino-3-methoxy-1-β-D-ribofuranosylpyrazolo[3,4-d]pyrimidin-4(5H)one ( 18 ). The guanosine analog, 6-amino-1-β-D-ribofuranosylpyrazolo[3,4-d]pyrimidine-3,4(2H,5H)-dione ( 21 ), was made by sodium iodide-chlorotrimethylsilane treatment of 6-amino-3-methoxy-1-(2,3,5-tri-O-acetyl-β-D-ribofuranosyl)pyrazolo[3,4-d]pyrimidin-4(5H)one ( 19 ), followed by sugar deprotection. Treatment of the adenine analog, 4-amino-1H-pyrazolo[3,4-d]pyrimidin-3(2H)-one ( 11 ), according to the high temperature glycosylation procedure yielded a mixture of N-1 and N-2 ribosyl-attached isomers. Deprotection of the individual isomers afforded 4-amino-3-hydroxy-1-βribofuranosylpyrazolo-[3,4-d]pyrimidine ( 26 ) and 4-amino-2-β-D-ribofuranosylpyrazolo[3,4-d]pyrimidin-3(7H)-one ( 27 ). The structures of 26 and 27 were established by single crystal X-ray diffraction analysis. The inosine analog, 1-β-D-ribofuranosylpyrazolo[3,4-d]pyrimidine-3,4(2H,5H)-dione ( 28 ), was synthesized enzymatically by direct ribosylation of 1H-pyrazolo[3,4-d]pyrimidine-3,4(2H,5H)-dione ( 8 ) with ribose-1-phosphate in the presence of purine nucleoside phosphorylase, and also by deamination of 26 with adenosine deaminase. 相似文献
73.
Gabor L. Szekeres Roland K. Robins Kay H. Boswell Robert A. Long 《Journal of heterocyclic chemistry》1975,12(1):15-19
Acetylation of 8-amino-9-β-D-ribofuranosylpurin-6-one (III), followed by chlorination of the tetraacetyl derivative 8-acetamido-9-(2,3,5-tri-O-aeetyl-β-D-ribofuranosyl)purin-6-one (IV) with phosphorus oxychloride yielded 8-aeetamido-6-ehloro-9-(2,3,5-tri-O-acetyl-β-D-ribofuranosyl)-purine (V). The 6-chloro substitutent of V was readily displaced with thiourea to give, after treatment with sodium methoxide 8-acetamido-9-β-D-ribofuranosylpurine-6-thione (VIII). Chlorination of 8-bromo-9-(2,3,5-tri-O-acetyl-β-D-ribofuranosyl)purin-6-one (IX) yielded 6,8-dichloro-9-(2,3,5-tri-O-acetyl-β-D-ribofuranosyl)purine (X), which underwent nucleophilic displacement with ethanolic ammonia selectively in the 8 position. The resulting 8-amino-6-chloro-9-β-D-ribofuranosylpurine (VII) was converted to 8-amino-9-β-D-ribofuranosylpurine-6-thione (I), 8-amino-6-methylthio-9-β-D-ribofuranosylpurine (II), and to 8-amino-6-hydrazino-9-β-D-ribofuranosylpurine (XI). 相似文献
74.
Frederick Cassidy Richard K. Olsen Roland K. Robins 《Journal of heterocyclic chemistry》1968,5(4):461-465
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. 相似文献
75.
Richard L. Tolman Roland K. Robins Leroy B. Townsend 《Journal of heterocyclic chemistry》1967,4(2):230-238
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. 相似文献
76.
Thomas Novinson Darrell E. O'Brien Roland K. Robins 《Journal of heterocyclic chemistry》1974,11(6):873-878
A number of imidazo[1,5-a]pyrimidine-8-carboxamides were synthesized by reacting various β-dicarbonyl compounds with 5(4)-aminoimidazole-4(5)carboxamide (AICA, 1 ), the non-ribosylated form of AICAR, a key intermediate in the metabolic pathway of purine biosynthesis. Cyclization of 1 with ethylacetoacetate yielded 2-methylimidazo[1,5-a]pyrimidin-1H-4-one-8-carboxamide ( 2 ). The treatment of 2 with phosphorus oxychloride gave 4-chloro-8-cyano-2-methylimidazo[1,5-a]pyrimidine ( 3 ). Various nucleophiles displaced the 4-chloro substituent of 3 under mild conditions. However, the 4-methylthio group of 8-cyano-2-methyl-4-methylthioimidazo[1,5-a)pyrimidine ( 8a ) was also displaced under very mild conditions. Even more strangely, the 4-diethylamino group of 8-cyano-4-diethylamino-2-methylimidazo[1,5-a]pyrimidine ( 5a ) was displaced by ammonia to give 4-amino-8-cyano-2-methylimidazo[1,5-a]pyrimidine ( 7 ). 相似文献
77.
78.
Naeem B. Hanna Steven B. Larson Roland K. Robins Ganapathi R. Revankar 《Journal of heterocyclic chemistry》1990,27(6):1713-1719
2-Amino-9-β-D-ribofuranosylpurine-2-sulfonamide (2-sulfamoyladenosine, 4 ), a congener of sulfonosine ( 3 ), was synthesized by four different routes. Acid catalyzed fusion of 6-chloropurine-2-sulfonyl fluoride ( 5 ) with 1,2,3,5-tetra-O-acetyl-β-D-ribofuranose ( 8 ) gave a good yield of 6-chloro-9-(2,3,5-tri-O-acetyl-β-D-ribofuranosyl)purine-2-sulfonyl fluoride ( 9 ). Ammonolysis of 9 furnished 4 . Lewis acid catalyzed glycosylation of the trimethylsilyl derivative of either 6-chloropurine-2-sulfonamide ( 6 ) or 6-aminopurine-2-sulfonamide ( 7 ) with 8 gave the corresponding N9-glycosylated products, 10 and 11 , respectively, which on ammonolysis gave 4 . Amination of 2-thioadenosine ( 12 ) with chloramine solution gave the sulfenamide derivative 13 , which on subsequent oxidation with m-chloroperoxybenzoic acid furnished an alternate route to 4 . The structure of 4 was established by single-crystal X-ray diffraction studies. 2-Sulfamoyladenosine ( 4 ) is devoid of significant inhibitory activity against L1210 leukemia in mice. 相似文献
79.
Two-photon sequential absorption spectroscopy has been used to selectively excite rotational structure in the B---X absorption transition of the 129I2 molecule up to within 2 cm−1 of the dissociation limit. Vibrational and rotational constants have been obtained for the B state levels with υ = 71–79. Le Roy's equations for long-range behaviour are expressed in mass-reduced form, and it is shown that these equations can be successfully used to combine the spectroscopic constants for 127I2 and 129I2 to give improved values of the long range constants for the B state. The improved values are only slightly different from those previously obtained by the same technique for 127I2 alone. 相似文献
80.