Dakin-west reaction with cysteine,cystine, and serine

Conclusions 3-Acetamido-4-acetylmercapto-2-butanone is formed when cysteine, cystine or serine is reacted with Ac₂O and either pyridine or -picoline in the presence of thioacetic acid.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1660–1661, July, 1977.     

The reaction of chloromethylsilanes with amines,hexamethyldisilazanes, and silylcarhamates

The reactions of chloromethylsilanes with amines, hexamethyldisilazane, and silylcarbamates were studied. The dependence of the composition and structure of the resulting products on the nature of the reagents used and reaction conditions was determined. A scheme for the synthesis of 4,9-diaza-2,7-dioxa-1,6-disilacyclodecane-3,8-dione derivatives was suggested.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1798–1801, October, 1994.     

The reaction of n,n-dibenzylcarbamoyl chloride with n-nitrosohydroxylamine

The action of N,N-dibenzylcarbamoyl chloride (2) on the sodium salt of N-nitrosohydroxylamines (1) in dry acetonitrile at reflux leads to products whose formation may be rationalized in terms of carbamoylation at either oxygen of the bidentate N-nitrosohydroxylamines.     

Grignard reaction with 2, 6-dialkoxydihydro- and -tetrahydropyrans

The Grignard reaction with 2, 6-dialkoxytetrahydropyran and 2, 6-dialkoxy-5, 6-dihydro-2H-pyran has been studied. In both cases the reaction takes place with the opening of the pyran ring and the formation of alkoxy-substituted saturated or , -unsaturated alcohols.During the complption of our work, a paper appeared in which the Grignard reaction with 2, 6-diethoxytetrahydropyran was studied [1].     

The reaction of visnaginone,khillinone, and o-hydroxy-acetophenone with Lawesson's reagent

Lawesson's reagent reacts with visnaginone ( 2a ), khillinone ( 2b ), and o-hydroxyacetophenone ( 5 ) to give the 1,2-oxaphosphinane derivatives 4a, 4b , and 6 , respectively.     

Silyl-substituted 1,3-butadienes for Diels-Alder reaction, ene reaction and allylation reaction

Silyl-substituted 1,3-butadienes are useful building blocks and are readily applied in several types of reactions such as Diels-Alder reaction, ene reaction and allylation. They can also participate in different tandem reactions such as Diels-Alder/allylation, ene/allylation, ene/allylation/Diels-Alder reaction, ene/allylation/ene reaction and ene/allylation/Diels-Alder/allylation reaction. This feature article reviews the synthesis of silyl-substituted 1,3-butadienes, and their applications in the reaction types mentioned above, involving a tandem Diels-Alder/ene/allylation process. This article also introduces some reactions of alkenylsilanes and allylsilanes for comparison and discussion about the tandem reaction. The tandem reactions described in this article are a powerful tool to construct complicated multicyclic compounds with high selectivity and high efficiency.     

Edge-bridged half-open zirconocenes: Synthesis, characterization, and reaction with diphenylacetylene

The synthesis and characterization of the new, 16 electron half-open zirconocenes, Zr(C₅H₅)(c-C₈H₁₁)(PR₃) (R = Me, Et) are reported, together with a structural study of the PEt₃ complex. As with other low valent half-open zirconocenes, the Zr-C distances are significantly shorter on average for the electronically open dienyl ligand than those for the C₅H₅ ligand, 2.343 vs. 2.512 Å. Reaction of either of these compounds with PhC₂Ph led to the incorporation of two equivalents of the alkyne, resulting in a formally 14 electron complex with coordination from cyclopentadienyl, allyl, σ-alkyl, and σ-vinyl units.     

Synthesis of nitro-substituted decalones by double Michael reaction,sequential Michael reaction,and by Diels-Alder reaction

4-Nitro-3-phenyl-decalones are obtained from 1-acetylcyclohexene by three different ways. Stereochemistry and reaction pathways are discussed, and, for the first time, an intermediate of a sequential Michael reaction is isolated.The Michael reaction is of great preparative value for the formation of CC bonds². We are especially interested in the stereochemistry of the double Michael reaction     

3, 5-二叔丁基邻苯二酚的过氧化降解偶合反应研究

3, 5-二叔丁基邻苯二酚过氧化氢氧化制备3, 5-二叔丁基邻苯醌时, 发现在氢氧化钾溶液中发生了氧化降解偶合反应, 制得了3, 5-二叔丁基-5-(2, 4-二叔丁基-6-羟基苯氧基)-2-呋喃酮 2; 并对其生成作了较合理的解释。     

The reaction of cysteine with α,β-unsaturated aldehydes

Cysteine adds in a two step reaction to acroleine, crotonaldehyde and 4-hydroxypentenal. The first addition products are the β-cysteinyl-substituted saturated aldehydes 1a, 1b and 3. Only the monoadduct of 3, which is stabilized through intramolecular hemiacetal formation, could be isolated. The derivatives 1a and 1b reacted rapidly with additional cysteine to give the thiazolidine compounds 2a and 2b. Whereas 2a and 2b were the only products even in reactions carried out with a molar ratio of aldehyde : cysteine ≧ 1, ratio < 1 was required to obtain a thiazolidine derivative in reactions with hydroxypentenal. The structures of compound 2a, 2b, 3 and 4 were ascertained by means of UV, IR and NMR measurements, potentiometric titrations, determination of the rate laws and elemental analysis. All adducts are in solution in equilibrium with cysteine and the parent aldehydes. Rate constants for forward and reverse reactions were estimated. The rate of forward reactions increase approx. 10-fold per pH unit in the pH range 2–10.     

Poly-2-vinylfuran,synthesis, characterization,and diels-alder reaction with maleic anhydride

Poly-2-vinylfuran, synthesized by free-radical polymerization of 2-vinylfuran, was characterized by nuclear magnetic resonance (NMR) and infrared (IR) spectroscopy. The pendant furan rings on the polymer backbone were then used as the diene component of a Diels-Alder reaction with maleic anhydride. The juxtaposition of the furan rings at first suggested an “avalanche” Diels-Alder reaction, in which the product of one cyclization would be the reactant of the next. A lack of polymer stereoregularity and the reversibility of the Diels-Alder reaction, however, prevented its formation. On the other hand, when the dienophile was used in a 1:1 molar ratio with respect to furan the smooth reaction produced a new polymer, the maleic anhydride adduct of poly-2-vinylfuran, which characterized by NMR and IR spectroscopy, was air stable and soluble in a number of solvents up to 70% transformation. When heated to 160°C the polymer reverted to maleic anhydride and somewhat decomposed poly-2-vinylfuran.     

Rhodium-catalyzed arylthiolation reaction of nitroalkanes, diethyl malonate, and 1,2-diphenylethanone with diaryl disulfides: control of disfavored equilibrium reaction

In the presence of catalytic amounts of RhH(PPh₃)₄ and 1,2-bis(diphenylphosphino)ethane (dppe), 1-nitroalkanes reacted with a diaryl disulfide giving 1-arylthio-1-nitroalkanes in air. The equilibrium to form thermodynamically disfavored products was shifted by the rhodium-catalyzed oxidation of thiols to disulfides and water. The thiolation reaction of cyclic nitroalkanes proceeded in high yields provided that suitable diaryl disulfides were employed depending on the substrate: di(p-chlorophenyl) disulfide was used for the thiolation reaction of 1-nitroalkanes, 1-nitrocyclopentane and 1-nitrocycloheptane with acidic α-protons (pK_a 16 and 17); di(p-methoxyphenyl) disulfide for 1-nitrocyclobutane and 1-nitrocyclohexane with less acidic α-protons (pK_a ca. 18). Related reactivities were observed in the thiolation reactions of malonate and 1,2-diphenylethanone.