Dichlorocarbene Research Articles

ChemInform Abstract: Addition of Dichlorocarbene on Organic Azides in Solid‐Liquid Phase‐ Transfer Catalysis.

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Addition of dichlorocarbene on organic azides in solid-liquid phase-transfer catalysis

The addition of dichlorocarbene on organic azides in homogeneous medium leads to isocyanide dihalides. In the conditions of the solid - liquid phase transfer catalysis, tetrachloroaziridines and isocyanide dihalides are obtained respectively as main products depending on whether a hydrogenated organic or whether a 2-F-alkylethyl azide is used.

A molecular orbital and crystallographic study of the structure and π-facial regioselectivity of 9-chloro-1,4,5,8-tetrahydro-4a,8a-methanonaphthalene

The title compound 1 undergoes reaction with electrophilic reagents such as dichlorocarbene regioselectively on the π-face endo to the chlorine. The crystal structure of 1 indicates significant geometrical distortions of the two rings, which we attribute to a stabilising interaction between the C–Cl σ* orbital and the exoπ-orbital. PM3 calculations of these orbitals, the electrostatic potential and transition state models for dichlorocarbene addition all agree with the observed regioselectivity.

Phase transfer catalysis: Kinetics and mechanism of hydroxide ion initiated dichlorocarbene addition to styrene catalysed by triethylbenzylammonium chloride

The kinetics of dichlorocarbene addition to styrene was studied under phase-transfer catalytic conditions using aqueous sodium hydroxide as the base and triethylbenzyl ammonium chloride as the phase-transfer catalyst. The reaction was carried out at 40°C under pseudo first-order condition by keeping aqueous sodium hydroxide and chloroform in excess. The fiogress of the reaction was monitored by gas chromatography. The effects of various experimental conditions on the rate of the reaction were studied and based on the results obtained a suitable mechanism has been proposed.

The chemistry of 1H-cyclopropa[b]naphthalene

1H-cyclopropa[b]naphthalene reacts with PTAD, tetracyanoethylene (TCNE) and benzyne to afford insertion-products 3, 4, and 5. Cheletropic addition of dichlorocarbene to 2 provides cyclobutanaphthalene 6. Hydrolysis and reductive elimination of 6 result in the formation of 7 and 8.

Synthesis of 3,3-dichloro-2-fluoroacrylic esters by thermal opening of alcoxy perhalogeno cyclopropanes

Alcoxyperhalogenocyclopropanes I are easily prepared by dichlorocarbene addition to the halogenated enol ether derived from chlorotrifluoroethylene, under PTC conditions. Thermal opening of the cyclopropane ring leads to the formation of 3,3-dichloro -2-fluoroacrylic ester II by chlorine atom departure from the CFCl group in preference to the one from the CCl 2 group. This selectivity could be due to the slowing down of the substitution by the other geminal chlorine atom in the latter case. ▪

Addition and Insertion Reactions of Dichlorocarbene and Chlorotrifluoromethyl-Carbene to Some Organometallics

Abstract Trifluoromethylchloro- and dichlorocarbenes were generated in situ, using various types of phase transfer catalysts/ and their addition/ insertion to various organometallic compounds containing M-M′ and M-CH2CH=CH2 bonds (where M, M′ are Si, Sn) have been studied. The resulting products have been characterised by elemental analysis, IR, 1H and 13C NMR data.

Proton-carbon-13 coupling constants in carbocations. 6. Generation and trapping of the (1a.alpha.,7a.alpha.)-1a,2,7,7a-tetrahydro-1H-cyclopropa[b]naphthalen-2-yl cation

New synthetic routes to (1aα,2β,7bα)-1a,2,3,7b-tetrahydro-1H-cyclopropa [a] naphthalen-2-ol (4b) and (1aα,2α,7aα)-1a,2,7,7a-tetrahydro-1H-cyclopropa [b] naphthalen-2-ol (6b) have been established involving dichlorocarbene addition to the appropriate dihydronaphthalene as the key step. Ionization of either alcohol 4b or 6b in FSO 3 H/SO 2 ClF at −130 o C produces the title cation 5b, in which the positive charge is stabilized by the adjacent benzo and cyclopropyl moieties. This is the same cation as that obtained previously by protonation of 1,6-methano [10] annulene (1). Generation of the cation 5b by protonation of C11- 13 C-enriched 1 has shown that the C11 bridge methylene carbon is incorporated into both benzylic positions (C2 and C7) and not the apical cyclopropyl carbon (C1). Application of the ΔJ equation shows that 5b adopts an anti-boat conformation in this superacid medium

Convenient synthesis of 1‐alkoxy‐1,2‐dihydrophosphinine 1‐oxides by ring enlargement

AbstractThe addition of dichlorocarbene to the double bond of 1‐alkoxy‐dihydrophosphole oxides and subsequent thermolysis of the adduct so obtained affords mixtures of the two double bond isomers of alkoxy‐dihydrophosphinine oxides, if the latter step is carried out in the presence of triethylamine. Experimental data support the involvement of a cationic intermediate during the opening of the cyclopropane ring. A simplified procedure for the preparation of the starting dihydrophospholes is also presented.

The Formation of Phosphacycloheptatrienes in Ring Enlargement Reaction

Abstract The forrmation of substituted phosphacycloheptatrienes in ring expansion reaction(s) is describzd. From thc: reac-tion of 3,4-dimethyl-l-phenyl-3-phospholene-l-oxide(1,R1 = c6H5, R2=R3 = CH3) with dichlorocarbene under liquid-liquid phase transfer circumstances not the expected adduct but the appropriate phoshacycloheptatrisne (4, Rl, R2,R3 as above) was prepared. The formation of this product can be explained assuming two ring expansions effected by two series of dichlorocarbene addition and cyclopropane ring opening. In the similar reaction of the methoxy-phospholenc derivative (1, R1=CH3O, R2 = R3 = CH3 four other products are also formed beside the phosphacyclohcptatriene. Again phosphacycloheptatrienes (4) are formed as the result of dichlorocarbene addition to the regioisoners of dihidrophosphorins (2) obtained from the phospholene-dichlorocarbene adducts by thermolysis. The same product can be derived from each regioisomeric pair.

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.

ChemInform Abstract: Synthesis and Conversions of Co2(CO)6‐1‐(1‐Alkynyl)‐6,6‐dichlorobicyclo(3.1.0)hexanes and Their 6‐Oxa‐ and 6‐Azaheteroatomic Analogues.

AbstractAddition of dichlorocarbene to the alkynylcyclopentenes (I) affords the rather unstable but isolable adducts (III).

ChemInform Abstract: Reaction of 1,2‐Octadiene and 5,6‐Undecadiene with Dichlorocarbene.

AbstractThe reaction between 1,2‐octadiene (I) and dichlorocarbene generated from CHCl3 (II) and tBuOK proceeds regiospecifically at C(2)=C(3) to afford the adduct (III).

Some transformations of adducts of dichlorocarbene and 7-substituted benzonorbornadienes

It was observed in the present study that the addition of dichlorocarbene to benzonobornadiene under phase-transfer catalysis conditions permitted the isolation of the exo adduct, which underwent isomerization to the exo allylic chloride only upon prolonged storage, or upon distillation

The Formation Of Phosphacycloheptatrienes In Ring Enlargement Reaction

Abstract The forrmation of substituted phosphacycloheptatrienes in ring expansion reaction(s) is describzd. From thc: reac-tion of 3,4-dimethyl-l-phenyl-3-phospholene-l-oxide(1,R1 = c6H5, R2=R3 = CH3) with dichlorocarbene under liquid-liquid phase transfer circumstances not the expected adduct but the appropriate phoshacycloheptatrisne (4, Rl, R2,R3 as above) was prepared. The formation of this product can be explained assuming two ring expansions effected by two series of dichlorocarbene addition and cyclopropane ring opening. In the similar reaction of the methoxy-phospholenc derivative (1, R1=CH3O, R2 = R3 = CH3 four other products are also formed beside the phosphacyclohcptatriene. Again phosphacycloheptatrienes (4) are formed as the result of dichlorocarbene addition to the regioisoners of dihidrophosphorins (2) obtained from the phospholene-dichlorocarbene adducts by thermolysis. The same product can be derived from each regioisomeric pair.

The stereochemistry of the 1,4-addition of dibromocarbene to 1,2-dimethylenecycloheptane

The stereochemistry of the 1,4-addition of dibromocarbene to 1,2-dimethylenecycloheptane

Reaction of photochemically generated dibromocarbene with 1,2-dimethylenecycloalkanes. 1,4-Addition is real

Les dibromocarbenes generes thermiquement ou photochimiquement s'additionnent a divers dimethylene-1,2 cyclanes pour donner des produits d'addition-1,2 et -1,4

Addition of dichlorocarbene to cis-1,4-poly(2-trimethylsilylmethyl-1,3-butadiene)

Copolymers made up of 1,4-(2,3-dichloromethylene-2-trimethylsilylmethyl-1,3-butadiene) (I) and 1,5-(3-chloro-2-methylene-pent-3-ene) (II) units have been prepared by potassium fluoride elimination of trimethylchlorosilane from cis-1,4-poly(2.3-dichloromethylene-2-trimethylsilylmethyl-1,3-butadiene) (III). III was prepared by the addition of dichlorocarbene to 1,4-poly-(2-trimethylsilylmethyl-1,3-butadiene) (cis/trans = 9/1) (IV). Polymer III was characterized by 1h, 13C and 29Si NMR as well as by elemental analysis. The copolymer was characterized by 1H, 13C and 29Si NMR spectroscopy. The ratio of I and II units in the copolymer were determined by 1H NMR and elemental analysis.

ChemInform Abstract: Regioselective Dichlorocarbene Addition to 2‐Vinyloxy‐3,4‐dihydropyrans.

AbstractPhase‐transfer catalyzed addition of dichlorocarbene to the vinyloxydihydropyrans (I) proceeds regioselectively at the vinyl group to give the dichlorocyclopropyloxydihydropyrans (III).

ChemInform Abstract: Synthesis, X‐Ray Crystal Structure, and Antimitotic Properties of 6‐Chloro‐2‐methoxy‐5‐(2′,3′,4′‐trimethoxyphenyl)cyclohepta‐2,4,6‐trien‐1‐one, a Bicyclic Analogue of Colchicine.

AbstractStarting with the isopropoxycyclohexenone (I), the dichlorobicycloheptenone (XVI) is prepared via addition of dichlorocarbene to the diacetoxycyclohexene (VIII).