理想微裂纹系统中的随机扩展效应

本文讨论了在理想微裂纹系统中,由于微裂纹的随机性扩展,对微裂纹统计演化产生的效应。文中提供了一般的理论框架,给出了便于处理的转移概率的表达式。最后,用数值计算的例子展示了随机模型的统计演化特征,并比较了与确定性扩展模型下统计演化的异同。     

Thermal rearrangement of 2,5-diaryl-3,3,4,4-tetracyanopyrrolidines

It was shown that briefly boiling solutions of 2,5-diaryl-3,3,4,4-tetracyanopyrrolidines in DMF caused rearrangement into 5-aryl-2-(N-arylidenamino)-3,4-dicyanopyrroles, which are methylated with diazomethane both at the NH bond and at the carbon atom of the azomethine fragment.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 42–46, January, 1995.     

Application of Horner–Emmons Olefination to the Crown-Ether Derivatives

An effective synthetic approach to the preparation of a new crown-ether vinylogs involving the Horner–Emmons olefination of carbonyl precursors with the use of C₂- and C₅-phosphonates was proposed. The effects of the conjugation chain length and the nature of the terminal polar functions in the phosphonate reagent on the yield and process stereoselectivity were discussed.     

Covalent chemistry and conformational dynamics of topologically chiral amide-based molecular knots

The readily available in gram quantities tris(allyloxy)knot of the amide-type 5 (knotane) can be completely and partially deprotected with nBu(3)SnH in the presence of a palladium catalyst resulting in hydroxyknotanes 7-9. These, in turn, react with diethylchlorophosphate giving rise to knotanes equipped with between one and three phosphoryl groups. Sulfonylation of bis(allyloxy)monohydroxyknotane 8 with p-toluenesulfonyl chloride and, following removal of one or two allyl groups from the intermediate monosulfonate 13, give rise to sulfonyloxy-allyloxy-hydroxy- and sulfonyloxy-dihydroxy-knotanes 15 and 14, respectively. This provides a convenient method for the preparation of knotanes with any substitution pattern. All new knotanes have been isolated in preparative amounts and as highly pure substances with an exception of allyloxy-dihydroxyknotane 9. This compound could only be obtained as a mixture with the corresponding monohydroxy-derivative 8. The structures of all synthesized compounds were established by means of FAB and MALDI TOF mass spectrometry, (1)H and (31)P NMR spectroscopy. The triphosphorylated knotane 10 exhibits high solubility in alcohols, allowing its complete enantiomeric resolution with a commercially available chiral HPLC column. (1)H,(1)H DQF-COSY correlation spectroscopy along with H/D exchange experiments and ab initio calculations provided the first detailed (1)H NMR signal assignments of knotanes in [D(6)]DMSO solution. The combination of variable temperature (1)H and (31)P NMR spectroscopy and molecular modeling has been applied to study the conformational behavior of the new knotanes in different solvents. It has been shown that in DMSO solution at room temperature knotanes exist in a relatively rigid nonsymmetrical conformation similar to that found in the solid state while faster conformational exchange leading to the average D(3) symmetrical structure was detected in a number of other solvents.     

Reaction of 4-oxoalkane-1,1,2,2-tetracarbonitriles with 1,3,5-trlaryl-2,4-diaza-1,4-pentadienes

2-Aryl-1,2,3,4-tetrahydropyridine-3,3,4,4,-tetracarbonitriles and 1,3,5-triaryl-9-oxo-1,2,3,4b,5,6,8a,9-octahydropyrido[3,4:3,4]pyrrolo[1,2-a][1,3,5]triazine-4b,8a-dicarbonitriles are formed by the reaction of 4-oxoalkane-1,1,2,2-tetracarnonitriles with 1,3,5-triaryl-2,4-diaza-1,4-pentadienes depending on the solvent used.Chuvash State University, Cheboksary 428015. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1395–1409, October, 1996. Original article submitted October 2, 1996.     

Synthesis of 2,5-distributed 3,3,4,4-tetracyanopyrrolidines

The reaction of 1,1,2,2-tetracyanoethane with 1-R,3-R,5-R-2,4-diazapenta-1, 4-dienes leads to 2,5-disubstituted 3,3,4,4-tetracyanopyrrolidines. The conditions for the acylation of the last were selected.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 353–358, March, 1994.     

Reaction of 3,3,4,4-tetracyanopyrrolidines with primary alcohols and amines

2,5-Substituted 3,3,4,4-tetracyanopyrrolidines react with primary alcohols in the presence of an excess of a base or with the base itself. 2-(N-Arylideneamino)-5-alkoxy-3,4-dicyanopyrroles are formed as a result of the reactions with alcohols, and 2,5-diamino-1-R-3,4-dicyanopyrroles are formed as the result of the reaction with primary aliphatic amines.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1502–1507, November, 1991.     

Chemistry of 1,1,2,2-tetracyanoethane. 14. Structure of 3-(N′,N′-dimethyl-N-acetylhydrazino)-5-methyl-1,1,2,2-tetracyanocyclopentane in solution and the crystal and the reasons for the selective addition of nucleophiles to a specific cyano group

For communication 13, see [1].     

Chemistry of 1,1,2,2-tetracyanoethane. 11. Synthesis and stereochemical characteristics of 3-methyl-5-oxo-2′-amino-5′-phenyl -3′,4′,4′-tricyanoisoxazoline-4-spiro-1′-cyclopent-2′-ene

The Michael condensation of 1,1,2,2-tetracyanoethane with 3-methyl-4-benzylideneisoxazolin-5-one having the Z configuration leads to a heterocyclic spiran with retention of the cis orientation of the phenyl and keto groups. The deviations of the series of bond angles of the spiran from the standard values, the abnormal lengths of the C-C bonds adjacent to the gem-dicyano group, and the appearance of nonbonding >C=O(...)CN interactions and conjugation effects in the enaminonitrile fragment are discussed.For Communication 10, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1404–1410, October, 1988.