Sigmatropic Rearrangements Accompanying the Addition of Dichlorocarbene to Norbornadiene

A new product arising from the reaction of dichlorocarbene with norbornadiene, 6endo-(2,2-dichlorovinyl)-cis-bicyclo[3.1.0]hex-2-ene, is described. It does not arise from the normal exo-l,2-adduct, but possibly originates by sigmatropic rearrangement of an initially formed zwitterionic intermediate.     

Dichlorocarbene addition to cyclopropenes: a computational study

Reaction paths for addition of dichlorocarbene to 1,2-disubstituted cyclopropenes were calculated using hybrid density functional theory (B3LYP/6-31G) in the gas phase and in the presence of a continuum solvation model corresponding to acetonitrile. In both the gas phase and acetonitrile, :CCl2-cyclopropene addition follows an asymmetric, non-least-motion approach. Barriers to addition range from 0 to 2 kcal/mol. The reactions proceed in concerted fashion in both the gas phase and solution to yield 1,3-dienes or bicyclobutanes. The reaction pathway on this complex potential energy surface of this reaction appears to bifurcate, and the product distribution is believed to be controlled by reaction dynamics. At the present level of theory, there appears to be no minimum on the potential energy surface corresponding to a dipolar intermediate.     

Ring Enlargement of Phospholenes to Phosphorin Derivatives Through Dichlorocarbene Adducts

Abstract

The ring enlargement of ready available phospholenes by dichlorocarbene addition to the double bond and subsequent opening of the cyclopropane ring is discussed. Adductcs of phospholene wih dichlorocarbene (2)can be synthetised under liquid-liquid phase transfer circumstances. The simplest bray to open the cyclopropane ring in the adducts is thermal transformation giving the two regioisomers of the appropriate dihydrophosphorin (3). Electrophilic reagents can also be used for -the opening of the cyclopropane ring. On heating with silver nitrate in water or in alcohols the adducts are transformed to the -two rcgioisomers of the hydroxy- or the alkoxy -tetrahydrophosphorins, respectively (4, Y=H, CH₃ C₂H₅) In the reaction of adducts with mercury acetate-acetic acid the corresponding acetoxy-derivatives (4, Y=CH₃CO) are formed. The Friedl Crofts reaction of the adducts with benzene iii the presence of aluminium trichloride yields diarylated product.     

Reactions of Thioketones with Dichlorocarbene

The reactions of sterically crowded cycloalkanethiones of type 2 with CHCl₃/NaOH under phase-transfer catalysis (PTC) with benzyl(triethyl)ammonium chloride (TEBA) as catalyst afforded the corresponding `gem.-dichlorothiiranes' of type 3 in good yields (cf. Scheme 2 and Table). The desulfurization, which, in some cases, occurred spontaneously, led to (dichloromethylidene)cycloalkanes of type 4 . Similar results were obtained using Seyferth's reagent in boiling benzene. In the case of 2,2,6,6-tetramethylcyclohexanethione, reaction under PTC conditions after 3 h yielded only the corresponding dichloromethylidene derivative; on the other hand, workup after 1 h gave (2,2,6,6-tetramethylcyclohexylidene)methanethione (thioketene 9 ; Scheme 5).     

Dehydration of Aldoximes by Dichlorocarbene in Reverse Micelle

The use of reverse micelle to catalyze the dehydration, on a preparative scale, of aldoximes to nitriles by dichlorocarbene is reported.     

Dichlorocarbene and analogs: discovery,properties and reactions

Russian Chemical Bulletin - The discovery and studies of chemistry of dichlorocarbene and other electron deficient carbenes are discussed.     

Preparation and Characterization of Dichlorocarbene Modified Multiple-walled Carbon Nanotubes

Multiple-walled carbon nanotubes were functionalized by cycloaddition of dichlorocarbene.The chemical modification was performed by using chloroform and sodium hydroxide.Various phase transfer catalysts were used to increase the efficiency of the reaction.Benzyltriethylammonium chloride used as phase transfer catalyst could highly enhance the effect of functionalization.Elemental analysis was used to evaluate the degree of functionalization.Characterization was performed using scanning electron microscopy(SEM)and transmission electron microscopy(TEM).Fourier transform infrared spectroscopy(FTIR)and energy-dispersive X-ray spectroscopy(EDS)were used to confirm the resulting material.     

二氯卡宾与四苯基环戊二烯酮反应机理的研究

二氯卡宾与四苯基环戊二烯酮（１）反应放出ＣＯ，并生成偕二卤化物（３）、二氯环氧乙烯（４）以及双键加成物（５）。羰基叶立德的芳香性结构及其“中介型”爸象决定了该应以脱ＣＯ为主电环化途径次之。     

Reaction of Dichlorocarbene with Substituted Cyclopentadienones Under Phase Transfer Conditions

The cycloaddition reactions involving dichlorocarbene generated under phase transfer conditions have been studied extensively in the past few years due to the simplicity of the procedure involved.¹ The facile formation of dichlorocyclopropanes provides an easy entry to functionalised aromatics and expanded carbocyclic compounds.² The dichlorocarbene generated under phase transfer conditions is capable of adding even to electron deficient olefins. We describe here the cyclo-addition reaction of dichlorocarbene to tetrasubstituted cyclopentadienones.     

Tetryl-Tetrylene Addition to Phenylacetylene

Phenylacetylene adds [Ar*GeH₂-SnAr’], [Ar*GeH₂-PbAr’] and [Ar'SnH₂-PbAr*] at rt in a regioselective and stereoselective reaction. The highest reactivity was found for the stannylene, which reacts immediately upon addition of one equivalent of alkyne. However, the plumbylenes exhibit addition to the alkyne only in reaction with an excess of phenylacetylene. The product of the germylplumbylene addition reacts with a second equivalent of alkyne and the product of a CH-activation, a dimeric lead acetylide, were isolated. In the case of the stannylplumbylene the trans-addition product was characterized as the kinetically controlled product which isomerizes at rt to yield the cis-addition product, which is stabilized by an intramolecular Sn–H–Pb interaction. NMR chemical shifts of the olefins were investigated using two- and four-component relativistic DFT calculations, as spin–orbit effects can be large. Hydride abstraction was carried out by treating [Ar'SnPhC=CHGeH₂Ar*] with the trityl salt [Ph₃C][Al(OC{CF₃})₄] to yield a four membered ring cation.     

二氯卡宾与甲醛环加成反应的理论研究

用从头算方法研究了单重态二氯卡宾与甲醛的环加成反应，找到了反应的中间配合物和过渡态，讨论了反应机理，发现该反应分两步进行，第一步生成中间配合物，第二步是中间配合物异构化为产物──二氯环氧丙烷．在从头算的基础上，用统计效力学方法和过渡态理论计算了该反应的热力学函数和动力学性质，并作了讨论．     

1-Alkyl-4-dialkylaminopyridinium Halides as Phase-Transfer Catalysts in Dichlorocarbene Reactions

 A series of 1-alkyl-4-dialkylaminopyridinium halides derived from 4-dimethylamino- and 4-morpholinopyridines were synthesized and tested as phase-transfer catalysts in three typical reactions of dichlorocarbene: dehydration of benzamide, N-formylation of diphenylamine, and dichlorocyclopropanation of styrene. The catalytic performance of the above compounds was found comparable or higher than that of conventional quaternary ammonium catalysts. The influence of catalyst structure on the reactivity was evaluated.