1,721,053 research outputs found
ChemInform Abstract: Cyclopropyl Building Blocks in Organic Synthesis. Part 73. Nucleophilic Trapping of π-Allylpalladium Intermediates Generated by Carbopalladation of Bicyclopropylidene: A Novel Three-Component Reaction.
No full textFrom ketazines to 1,2-diaza-3-phospha-cyclopent-5-enes, penta-3,5-dienes, 1,5-diaza-2,6-diphospha-bicyclo[3.3.0]octa-3,7-diene, and cyclohexaphosphane
No full textThe dilithium salt of di(tert-butyl-methyl)ketazine 1 reacts with the bimolar amount of ClSiMe3 to give the di(tert-butyl-trimethylsilylmethylen)ketazine, 2. In the reaction of lithiated 2 and F2PN(iPr)(2) the 1,2-diaza-3-phosphacyclopent-5-ene (3) is formed. The dichlorophosphanes Cl2PC6H5 and Cl2PCMe3 react with 1 in boiling toluene to give the 1,2-diaza-3-phosphacyclopentenes 4 and 5. The oxygen of the air oxidizes 5 to the 1,2-diaza-3-phosphacyclopent-5-ene 6. Equivalent amounts of H2O cleave the ring skeleton of 5, the tert-butyl-methyl-(tert-butyl-(tert-butylphosphino)methyl-ketazine 7 being formed. The 1,2-diaza-3-phosphacyclopenta-3,5-diene 8 and the 1,5-diaza-2,6-diphospha-bicyclo[3.3.0]octa-3,7-diene 9 are the reaction products of 1 and PCl3 in toluene. 1 forms with HCl the hydrochloride 10. The 5-tert-butyl-1,2-diaza-3-phospha-cyclopenta-3,5-diene 11 is isolated from the reaction of 9 and MeLi. 11 is also obtained from PCl3 and tert-butyl-methyl-hydrazone in good yields. The cyclohexaphosphane 12 was formed in the reaction of 9 with Na/K alloy. The results of the crystal structure analyses of 2, 3, 6, 10, and 12 are reported
Dipheno-silyliminoquinones - A (14)pi-system
No full textLithium salts of 2.6-dialkylanilines react with di-tert-butylfluorosilanes to give mono (1-3) - and bis (7, 8)-(2.6-dialkylphenylamino)silanes. Amino-2.6-dimethylphenyl-(di-tert-butylfluoro)silane (1) forms with BuLi a dimeric lithium salt (4) containing an eight-membered (LiFNSi)(2) ring system. Thermally, 4 loses LiF and a bicyclic compound (9) via iminosilenes is obtained. The lithium salt of the bulkier amino-2.6-diisopropylphenyl-(di-tert-butylfluorosilanes) (5-7) thermally loses LiH and iminosilanes (10-12) with a 14 pi-system are isolated. The reaction mechanisms and crystal structures are discussed. (c) 2006 Elsevier B.V. All rights reserved
From ketazines to 1,2-diaza-3-phospha-cyclopent-5-enes, penta-3,5-dienes, 1,5-diaza-2,6-diphospha-bicyclo[3.3.0]octa-3,7-diene, and cyclohexaphosphane
No full textThe dilithium salt of di(tert-butyl-methyl)ketazine 1 reacts with the bimolar amount of ClSiMe3 to give the di(tert-butyl-trimethylsilylmethylen)ketazine, 2. In the reaction of lithiated 2 and F2PN(iPr)(2) the 1,2-diaza-3-phosphacyclopent-5-ene (3) is formed. The dichlorophosphanes Cl2PC6H5 and Cl2PCMe3 react with 1 in boiling toluene to give the 1,2-diaza-3-phosphacyclopentenes 4 and 5. The oxygen of the air oxidizes 5 to the 1,2-diaza-3-phosphacyclopent-5-ene 6. Equivalent amounts of H2O cleave the ring skeleton of 5, the tert-butyl-methyl-(tert-butyl-(tert-butylphosphino)methyl-ketazine 7 being formed. The 1,2-diaza-3-phosphacyclopenta-3,5-diene 8 and the 1,5-diaza-2,6-diphospha-bicyclo[3.3.0]octa-3,7-diene 9 are the reaction products of 1 and PCl3 in toluene. 1 forms with HCl the hydrochloride 10. The 5-tert-butyl-1,2-diaza-3-phospha-cyclopenta-3,5-diene 11 is isolated from the reaction of 9 and MeLi. 11 is also obtained from PCl3 and tert-butyl-methyl-hydrazone in good yields. The cyclohexaphosphane 12 was formed in the reaction of 9 with Na/K alloy. The results of the crystal structure analyses of 2, 3, 6, 10, and 12 are reported
Bis(1-cyclohexene-3-on-1-oxy)silanes, silyl-enoles of beta-ketones
No full text5,5-Dimethylcyclohexane-1,3-dione (dimedone) and cyclohexane-1,3-dione react with Cl2Si(CMe3)(2) in the presence of triethylamine to give the bis(1-cyclohexene-3-on-l-oxy)di(t) butyl-silanes 2 and 3. Using dimedone and Cl2SiMe2, the analogous dimethylsilane 1 is obtained. A 1,4-Michael-Addition occurs using cyclohexane-1,3-dione in the reaction with Cl2SiMe2 to give a spirocyclic diketone (4). The reaction of cyclohexane-1,3-dione with lithium-diisopropylamide and F3SiCMe3 leads to the formation of a salt [(Pr2NH2)-Pr-i](2)HF[C6H7O2](2), 5. The crystal structures of 2-5 were determined
Percycloalkylated cyclohexanes: attempted synthesis of a trispropellane
No full textThe acid catalyzed rearrangement of two cyclohexanols of spiroannelated four-membered rings has been studied. In accordance with molecular mechanics calculations, far-reaching reorganizations with formation of unsaturated hexacyclic systems, including a fully cycloalkylated cyclohexene with a bispropellane Partial structure, were observed. Attempts to convert this bispropellane to a trispropellane failed. (C) 2009 Elsevier Ltd. All rights reserved
ChemInform Abstract: Cyclization and Isomerization Reactions in Silylhydrazine Chemistry
No full textStructural, electrochemical and oxygen atom transfer properties of a molybdenum selenoether complex [Mo2O4(OC(3)H(6)SeC(3)H6(O))(2)] and its thioether analogue [Mo2O4(OC3H6SC3H6O)(2)]
No full textThe first crystallographically characterized molybdenum(VI) selenoether complex [Mo2O4(OC3H6SeC3H6O)(2)] and its thioether analogue [Mo2O4(OC3H6SC3H6O)(2)] were synthesised. Their structural, electrochemical and oxygen atom transfer properties are compared. This is relevant for the molybdenum cofactors of the DMSO reductase family where the coordination of the active site metal occurs through O (serine/aspartate), S (cysteine) or Se (selenocysteine). Both structures are almost identical except for those parameters that are directly derived from the different sizes of the varied ligand atoms (Se and S). No trans influence was observed. The metal centered redox process ((MoMoVI)-Mo-V ($) over left right arrow) is at slightly lower voltage for the sulfur than for the selenium complex. The selenium compound catalyses the oxygen atom transfer from DMSO to PPh3 by a different mechanism and at a higher rate than the sulfur compound, which is an indication that cysteine and selenocysteine might be used for a purpose in the different molybdenum and tungsten cofactors
Cyclization of di(tert-butyl-methyl)ketazine to 1,2-diaza-3-bora- and 1,2-diaza-3-sila-cyclopent-5-enes
No full textThe results of quantum chemical calculations on lithium ketazides suggest mainly four isomeric structures with different modes of lithium coordination (A-D). A monolithium ketazide thf-adduct (1) was isolated supporting the results of the quantum chemical calculations. In reactions of the lithiated di(tert-butyl-methyl)ketazine with BCl3 and Cl2BPh, 1,2-aza-azonia-3-borata-cyclopent-5-enes (2,3) were isolated. Substitution of a chlorine atom of 2 and 3 with t-BuLi leads to the formation of derivatives 4 and 5. HCl elimination from 2 with Et3N gives - via a diazaboracyclopentene (6) - a bicyclus 7. In the reaction of the dilithiated ketazine with F2BN(SiMC3)(2), the diaza-boracyclopentene 8 is obtained while with Cl4Si, F3SiN(SiMe3)(2), and Cl2SiMe2 the diazasilacyclopentenes 9 - 11 are generated. SiF4 reacts with the dilithium ketazide to give a spirocyclus (12). The monolithium ketazide and Cl2SiMe2 react at 30 degrees C to give a four-membered ring isomer of the substitution product which is formed via a 1,3-chlorine shift from silicon to carbon (13). A tetrameric silanolate was isolated as a by-product in this reaction. It gives evidence for the structure of lithium ketazide A. Crystal structures of 5, 7, 10, and 14 are reported
ChemInform Abstract: Facile Synthesis of 7-Dimethylamino-endo-tricyclo[5.2.2.01,6]undec-10-en-9-ones.
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