Cyanoacetylene and Its Derivatives: XXXI. Nucleophilic Addition of 2- and 4-Mercaptopyridines to Cyanacetylenes

Reactions of nucleophilic addition of 2- and 4-mercaptopyridines to 3-phenyl-2-propynonitrile, 4-hydroxy-4-alkyl-2-alkynonitriles, and methyl 2-butynoate (triethylamine, 20-25 or 100°C) give rise to the corresponding S-adducts with Z-configuration (for cyanoethylenes), or to a mixture of E- and Z-isomers in 60:40 ratio for methyl 2-butynoate.     

Reactions of 1-acyl-2-bromoacetylenes with dithiocarbamic acids

2-Acyl-2-bromoacetylenes react with dithiocarbamic acids in aprotic solvents (acetonitrile, chloroform, or ether) to give 5-acyl-2-diethylamino(heteryl)-1,3-dithiolium bromides, which on reaction with secondary amines (diethylamine or morpholine) undergo cleavage of the 1,3-dithiole ring to give 1-acyl-2-diethyl(morpholyl)dithiocarbamoyl-2-diethylamino(morpholyl)ethylenes. X-ray crystallographic studies on the product from one of these reactions has shown it to be 5-thenoyl-2-diethylamino-1,3-dithiolium bromide.Institute of Organic Chemistry, Siberian Branch, Russian Academy of Sciences, 664033 Irkutsk. A. V. Shubnikov Institute of Crystallography, Russian Academy of Sciences, 117331 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 8, pp. 1850–1856, August, 1992.     

Reaction of ethynylsilanes with perfluoroiodoalkanes

Conclusion The addition of iodotrifluoromethane, 1-iodoperfluoropropane, and 1-iodo-1,1,2,2,3,3,4,4-octafluorobutane to alkylethynyl- and alkylalkoxyethynylsilanes gave the 1-iodo-3,3,3-trifluoropropen-1-ylsilanes, 1-iodo-3,3,3,4,5-5,5-heptafluoropenten-1-ylsilanes, and 1-iodo-3,3,4,4,5,5,6,6-octafluorohexen-1-ylsilane. The corresponding fluorosilanes were synthesized by reacting the latter with 40% aqueous HF solution.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1424–1428, June, 1982.     

Trofimov Reaction with Oximes Derived from Ketosteroids: Steroid-Pyrrole Structures

Steroidal ketone oximes, namely pregnenolone oxime, ⁵-cholesten-3-one oxime, and progesterone dioxime react with acetylene in superbasic systems (Trofimov reaction) to afford steroid-pyrrole assemblies. The process is accompanied by prototropic migration of double bonds in the steroid fragment and vinylation of hydroxy groups in sterols with acetylene. The O-vinyl group can readily be removed by methanolysis.     

Trifluoroacetylation of Ketone O-Vinyloximes

Ketone oxime O-vinyl ethers having alkyl or phenyl radicals react with trifluoroacetic anhydride in ether in the presence of pyridine, yielding 43-54% of the corresponding ketone oxime O-(trans-4,4,4-trifluoro-3-oxo-1-butenyl) ethers with high stereoselectivity.     

Helical complexes of oligonucleotides with derivatives of oligoamides. Specificity of complementary recognition

The method of molecular mechanics with an AMBER 3.0 computer software package, supplemented by specially developed subprograms, was used to carry out a conformational analysis of hybrid double helices with noncanonical H-bonds composed of oligodeoxyribonucleotide and oligoamide fragments (dT)₅ · (pT)₅ (1) and (dA)₄(dT)₂(dA)₄ · (dT)₃(pT)₄(dT)₃ (2). The purpose of the work was to perform a pre-synthesis estimation of Watson—Crick specificity of binding specially constructed oligomers, which carry oligoamide inserts of 2-aminoethylglycine units in the center, connected to nitrogen bases through a methylenecarbonyl group. A comparison of helical parameters and potential energies in optimized structures of hybrid oligonucleotides with noncanonical T · T-pairs with the energies of analogs containing only canonical A · T-pairs showed that disruption of Watson—Crick complementarity results in a crucial distortion of hybrid double helices, which leads to their destabilization. For this reason, the expected probability of mispairing of oligonucleotides is low for the proposed analogs of oligonucleotides carrying oligoamide inserts. Hence, the synthesis of these oligonucleotides is promising for creating reagents with selective action on single-stranded oligonucleotides inside cells.Papers presented in the section Chemistry of Natural Compounds and Bioorganic Chemistry of this issue are based on the materials delivered at the XII Seminar on Intermolecular Interactions and Conformation of Molecules, Khar'kov, October 3–8, 1994.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1364–1368, July, 1995.