Synthesis and reactivity of azapalladacyclobutanes

N-Sulfonyl aziridines undergo oxidative addition to palladium(0) complexes generated in situ from mixtures of Pd2(dba)3 and 1,10-phenanthroline. The resulting azapalladacyclobutane complexes undergo intramolecular carbopalladation in the presence of copper(I) iodide to afford azapalladabicyclo[3.2.1]octanes. A deuterium-labeling experiment indicates that the oxidative addition proceeds via SN2-type attack of palladium(0) on the less-hindered carbon of the aziridine ring and that alkene insertion occurs in a syn fashion. The azapalladabicyclo[3.2.1]octane complexes undergo oxidative palladium-carbon bond functionalization in the presence of copper(II) bromide.     

Synthesis and reactivity of aminofuroxans

Chemistry of Heterocyclic Compounds - In this review article, we provide general information on the known methods for directed synthesis of 3- and 4-aminofuroxans, as well as analyze the main...     

Thiophenium-ylides: Synthesis and reactivity

The reaction of propanedioic acid, 2-diazo-1,3-bis(1,1-dimethylethyl) ester (di-tert-butyl diazomalonate) with a series of cyclopenta[b]thiophenes in the presence of catalytic rhodium acetate was studied. The resulting S—C ylides underwent a rearrangement to form a heterocycle with different topology; thialene, in very low yields. Experimental and spectral data for all compounds are provided.     

Synthesis and reactivity of polydisulfonimides.

The first synthesis of alkyl disulfonimide oligomers is presented. In the process of synthesizing these oligomers, previously unreported reactivity of the N-substituted disulfonimide functional group was discovered. Under basic conditions, unexpected lengthening of the oligomers occurs through a "transdisulfonimidation" reaction, whereby new disulfonimides are synthesized from existing ones by reaction with sulfonamide anion. This process appears to proceed via formation of a sulfene intermediate. Support for the E1cB(Rev) mechanism includes isotope scrambling, substituent effects, and sulfene trapping.     

Synthesis and reactivity of metal-containing monomers

The polymerization of diacrylates of the nontransition metals Mg, Zn, Ba, and Pb, which proceeds at low temperatures (5–10°C) with the complexes of alkylcobalts with tridentate Shiff bases (RCo) as initiators, was studied. The radical mechanism of the process was proved with the aid of free radical scavengers. The polymerization kinetics is given by the equationW _n = k [M] · [RCo]^0.75. The influence of the nature of the metal in the monomer and the alkyl ligand in the initiator on the polymerization process was discussed. Low temperatures promote the formation of polymers with high molecular weights and a predominantly syndiotactic structure. The effect of the steric hindrances arising during polymerization due to the formation of a three-dimensional cross-linked structure in the metal-containing polymer on the microstructure of polymer chain and on polymerization kinetics was considered.For part 24 seeBull. Acad. Sci., Div. Chem. Sci., 1992, 1609.For a preliminary communication see Ref.1.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 500–503, March, 1993.     

Synthesis and reactivity of indolylmethyl cations

The synthesis of diindolylmethyl cations by reaction of aldehydes and indoles is described, and their reaction with Grignard reagents, organo-lithium compounds and sodium borohydride, giving the corresponding diindolyl methanes, is reported. The analogous phenyl indolylmethyl cations could never be isolated, but their formation was proved indirectly.     

Synthesis and Diels-Alder reactivity of ortho-carbazolequinones

Oxidation of 2- and 3-hydroxycarbazoles with Frémy's salt gave the corresponding ortho-carbazolequinones. These molecules react as carbodienophiles in Diels-Alder reaction with 1-acetoxy-1,3-butadiene and 1,3-cyclopentadiene to provide the novel benzocarbazolequinone structures 15, 16, 18 and 19.     

Synthesis and reactivity of metal-containing monomers

Acid and neutral Co^II, Cu^II, Ni^II, Zn^II, Fe^II, and Fe^III maleates, fumarates, and itaconates were obtained and characterized. The methods for their synthesis were optimized, and the valence state and coordination of metals were studied. Co^II and Fe^II hydrogen maleates, Co^II maleate, and Co^II fumarate were examined by X-ray diffraction analysis. The ligands based on unsaturated dicarboxylic acids can be mono-, bi-, and tetradentate, which results in the formation of acid salts, chain and three-dimensional coordination polymers, whose double bond is not involved in the coordination. The strong antiferromagnetic exchange (μ_elf=1.41 and 0.34 μ_B at 290 and 80 K, respectively) was detected in Cu^II itaconate. Based on the data of Mössbauer spectroscopy, the partial reduction of Fe^III to Fe^II during the synthesis of Fe^III maleate was shown to occur: δFe=0.43 and 1.27 mm s^?1, ΔE _Q=0.57 and 3.13 mm s^?1 and Γ=0.37 and 0.28 mm s^?1 atT=298 K for Fe^III and Fe^II, respectively.     

Synthesis and reactivity of cyclam-based enediynes

Cyclam-based enediynes 1-3 have been synthesized for the first time either by direct bis- or tetra-alkylation of the cyclam or via double alkylation of the 1,8-bis-sulfonyl derivative. The enediyne 1 readily forms a complex with Ni(II), which also lowered the onset temperature for Bergman cyclization of the parent enediyne by 60 °C. In the presence of a co-oxidant, MMPP, the Ni-complex can cleave ds-DNA into the nicked relaxed form at micromolar concentrations.     

异核双金属有机化合物的合成方法与反应性能研究

本文对近年来异核双金属有机化学的发展作了简要的介绍和回顾, 文中对含金属-金属键和不含金属-金属键的d/d和d/f异核双金属有机化合物的合成方法及反应性能作了归纳。     

Synthesis and reactivity of 10-Alkylphenotellurazines

The reaction of N-alkyl-2,2-dilithium diphenylamines with tellurium diiodide yields derivatives of a new heterocyclic system, phenotellurazine. 10-Alkyl-phenotellurazines readily form derivatives containing tetra- and tricoordinated tellurium, form complexes with metal salts and rhodium(I) carbonyl chloride, and by bromination and nitration give 3,7-dibromo- or 3-nitro-, 3,7-dinitro, and 1,3, 7,9-tetranitro derivatives.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 757–768, June, 1985.     

Synthesis and reactivity of diethyl phosphonomethyltriflate

Diethyl phosphonomethyltriflate, prepared from diethyl hydroxymethyl—phosphonate, readily reacts in good to excellent yields with a variety of oxygen and nitrogen nucleophiles.     

Synthesis and reactivity of metal-containing monomers

Thermal transformations of Fe^III maleate, [Fe₃O(OOCCH=CHCOOH)₆]OH·3H₂O (1), in an autogenerated atmosphere and the change in the short-range surrounding of Fe atoms during thermolysis were studied. The thermal transformations of1 are accompanied by the following processes: dehydration with simultaneous rearrangement of the ligand environment and formation of maleic acid, and polymerization of the rearranged monomer and its decarboxylation at high temperatures. In the initial stage of decarboxylation, the destruction of the metal-carboxylate Fe₃O complex occurs followed by the formation of the Fe−Fe bond (r=0.246 nm). The oxidation of the Fe atoms is observed when the thermolysis duration increases. For Part 49, seeIzv. Akad. Nauk, Ser. Khim., 1998; 1145 [Russ. Chem. Bull., 1998,47, 1113 (Engl. Transl.)]. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1505–1510, August, 1998.     

Synthesis and reactivity of metal-containing monomers

Optically active mixed alkoxy orthotitanates with general formula Ti(OR¹)₂(OR²)(OR³) (R¹=Et, Buⁿ; R²=CH₂CH₂OCOC(Me)=CH₂; R³=menthyl, CH(Me)CH₂Me, CH(Ph)CH(NHMe)Me, CH(C₉H₆N)(C₉H₁₄N)) were obtained for the first time by transesterification. The Ti^IV monomers synthesized were characterized by elemental analysis, ozonolysis, and¹H and¹³C NMR and IR spectroscopy. Polymer products with optical activity were obtained by liquid phase radical copolymerization of Ti^IV-containing monomers. For Part 51, see Ref. 1. Deceased. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1739–1743, September, 1999.     

Synthesis and reactivity of O-acyl selenophosphates

The synthesis of several new O-acyl selenophosphates were investigated. The stability and reactivity of the products were studied and related to their structure.     

Synthesis and reactivity of metal-containing monomers

The reaction of Rh₆(CO)₁₅MeCN with allyldiphenylphosphine under mild conditions afforded the cluster-containing complex [Rh₆(CO)₁₄(μ,η²-PPh₂Ch₂CH=CH₂)]. Its molecular structure was characterized. The resulting complex is an octahedral Rh cluster with ten terminal and four μ₃-bridging CO ligands. The average Rh?Rh distance is 2.762(2) Å. The unsaturated ligand is additionally coordinated to the metal center (Rh(4)–C(232), 2.37(1) Å; and Rh(4)–C(233), 2.32(2) Å) to form a π-bond.     

Synthesis and reactivity of 5-methylenehydantoins

5-Methylenehydantoin, as well as the N-mono- and N,N-di-protected derivatives, can be obtained by different synthetic routes. These compounds can undergo a large variety of reactions, such as Diels-Alder, epoxidation, methanol addition and conjugate addition reactions of different types of nucleophiles, including carbon (cyanide), nitrogen (piperidine) and sulfur (thiols, thioacetate) nucleophiles. The reactivity with electrophilic reagents, such as m-CPBA or methanol in acidic medium, and the need for Lewis acids to promote the conjugate addition reactions indicate that hydantoin is a poor electron-withdrawing group.     

Synthesis of glycosylthiols and reactivity studies

The acid-catalyzed reaction of 1,2-anhydro-3,4,6-tri-O-benzyl-α-d-glucopyranose (7) as glycosyl donor with bis-trimethylsilyl sulfide as acceptor affords the α-thiol. Hence, this sterically hindered S-nucleophile as acceptor should provide with O-glycosyl trichloroacetimidates as glycosyl donors that have nonparticipating groups at C-2, glycosylthiols with the thiol group in axial position. This was confirmed for various donors (4, 16-19) with the exception of the corresponding mannosyl donor (20). However, powerful participating groups at C-2 of the donor (23-28) governed the anomeric selectivity.