Iron(III)-promoted aza-Prins-cyclization: direct synthesis of six-membered azacycles

[reaction: see text] A new iron(III) halide-promoted aza-Prins cyclization between gamma,delta-unsaturated tosylamines and aldehydes provides six-membered azacycles in good to excellent yields. The process is based on the consecutive generation of gamma-unsaturated-iminium ion and further nucleophilic attack by the unsaturated carbon-carbon bond. Homoallyl tosylamine leads to trans-2-alkyl-4-halo-1-tosylpiperidine as the major isomer. In addition, the alkyne aza-Prins cyclization between homopropargyl tosylamine and aldehydes gives 2-alkyl-4-halo-1-tosyl-1,2,5,6-tetrahydropyridines as the only cyclic products.     

Bis(trifluoromethyl)-containing 1-azatricycloheptanes

6-Substituted 7-halo-3,3-bis(trifluoromethyl)-2-azabicyclo[2.2.1]heptanes were synthesized by the addition of water, alcohols, and acetic acid to 3-halo-7,7-bis(trifluoromethyl)-1-azatricyclo[2.2.1.0^2,6]heptanes in the presence of H₂SO₄. 5,6-Disubstituted 3,3-bis(trifluoromethyl)-2-azabicyclo[2.2.1]heptanes were prepared by oxymercuration of 3,3-bis(trifluoromethyl)-2-azabicyclo[2.2.1]hept-5-ene.     

Synthesis of enantiopure imidazolines through a Ritter reaction of 2-(1-aminoalkyl)aziridines with nitriles

The Ritter reaction of enantiopure 2-(1-aminoalkyl)aziridines 1 with different nitriles afford enantiopure tetrasubstituted imidazolines 2. The opening of the aziridine ring takes place with total regio- and stereoselectivity. A mechanism to explain the described addition reaction is proposed. [reaction: see text]     

Reactions of some ortho and para halogenated aromatic nitriles with ethylenediamine: selective synthesis of imidazolines

The reaction of ethylenediamine (EDA) with ortho and/or para halogenated benzonitriles did not lead to the imidazolines expected: a competitive aromatic nucleophilic substitution (S_NAr) was observed instead. The selective synthesis of these imidazolines was performed by nucleophilic addition of EDA to thiobenzamide derivatives. The difference in reactivity between the nitrile and thioamide derivatives was estimated by a frontier orbital approach at the RHF/6-31G** level which predicted a greater reactivity of substituted thiobenzamides towards the nucleophilic addition of EDA.     

Catalytic reduction and intramolecular cyclization of haloalkynes in the presence of nickel(I) salen electrogenerated at carbon cathodes in dimethylformamide

[reaction: see text] Pentylidenecyclopentane can be conveniently prepared in up to 86% yield via the catalytic reduction of 1-iodo- or 1-bromo-5-decyne by [[2,2'-[1,2-ethanediylbis(nitrilomethylidyne)]bis[phenolato]]-N,N',O,O']nickelate(I) electrogenerated at a carbon cathode in dimethylformamide containing tetramethylammonium tetrafluoroborate. This electrosynthesis can be accomplished at potentials for which the haloalkynes are electroinactive, and it can be completed within 30 min at room temperature. Attempts to synthesize pentylidenecyclobutane and pentylidenecyclohexane from 1-halo-4-nonynes and 11-halo-5-undecynes, respectively, under similar conditions afford the carbocycles in very low yields (2% and 6%, respectively). Other products derived from the various haloalkynes are dimers, alkynes, and 1-alkenynes. Dimers (alkadiynes) arising from 1-halo-4-nonynes and 11-halo-5-undecynes are formed in yields ranging from 80% to 89%, whereas icosa-5,15-diyne (the dimer obtained from a 1-halo-5-decyne) is found in significantly lower yield (相似文献   

Synthesis of polyhydroxylated 2H-azirines and 2-halo-2H-azirines from 3-azido-2,3-dideoxyhexopyranoses by alkoxyl radical fragmentation

The reaction of 3-azido-2,3-dideoxypyranose and 3-azido-2,3-dideoxy-2-halohexopyranose compounds with (diacetoxyiodo)benzene and iodine generated 2-azido-1,2-dideoxy-1-iodoalditols and 2-azido-1,2-dideoxy-1-halo-1-iodoalditols, respectively. These beta-iodo azides could be transformed by chemoselective dehydroiodination into 2-azido-1,2-dideoxy-4- O-formyl-pent-1-enitols and (Z, E)-2-azido-1,2-dideoxy-1-halo-4- O-formyl-pent-1-enitols in good yields. Thermolysis and photochemical studies of these vinyl azides and 1-halovinyl azides for the synthesis of polyhydroxylated 3-alkyl-2 H-azirines and the hitherto unknown 2-halo-3-alkyl-2 H-azirines have also been accomplished.     

Synthesis of 4-Halo-3-isopropoxyfuro[3,4-с]-pyridin-1(3H)-ones

Russian Journal of Organic Chemistry - The reaction of 4-halo-3-hydroxyfuro[3,4-c]pyridin-1(3H)-ones with propan-2-ol leads to the formation of 4-halo-3-isopropoxyfuro[3,4-c]pyridin-1(3H)-ones. The...     

A new halopropargylation of alkynes promoted by boron trihalides. highly stereo- and regioselective syntheses of substituted (Z)-1-halo-1,4-enyne derivatives

[reaction: see text] A new halopropargylation of alkynes promoted by boron trihalides has been developed. Reactions of (Z)-2-halo-1-vinylboron dihalides (generated in situ via reaction of alkynes with boron trihalides) with lithium propargyloxides in CH(2)Cl(2) at room temperature produce the corresponding (Z)-1-halo-1,4-enynes in modest to good yields.     

Liquid chromatography/electrospray ionisation mass spectrometric investigations of imidazoline corrosion inhibitors in crude oils

The so-called imidazolines (2-alkyl-1-[ethylalkylamide]-2-imidazolines and 2-alkyl-1-ethylamine-2-imidazolines) are a group of surface-active compounds, complex mixtures of which are used by various industries as surfactants and corrosion inhibitors. Although their industrial synthesis was reported over 100 years ago, few methods for the determination of individual imidazolines in mixtures, including industrial matrices such as crude oils, have been reported. Here we demonstrate that spiking of crude oils with synthetic imidazolines followed by solid-phase extraction and liquid chromatography/electrospray ionisation multistage mass spectrometry (LC/ESI - MS(n)) allows an estimation of low (<10) parts per million concentrations of individual imidazolines in crude oils. Whilst non-optimised at present, the method is a significant advance and may prove useful not only for improving an understanding of the mechanisms of industrial imidazoline synthesis and for monitoring downhole and topside oilfield operations, but also for the determination of the fate of imidazoline-based oilfield corrosion inhibitors and surfactants in the environment.     

Direct carbon-carbon bond formation via soft enolization: aldol addition of α-halogenated thioesters

α-Halo thioesters undergo soft enolization and syn-selective direct aldol addition to aldehydes in the presence of MgBr(2)·OEt(2) and i-Pr(2)NEt to produce α-halo-β-hydroxy thioesters.     

Bi(OTf)3-catalyed One-pot Synthesis of α-Halo-β-amino Ketones and Acyl Aziridines from 3-Aryl Propargyl Alcohols

A Bi(OTf)₃-catalyed reaction of 3-aryl propargyl alcohols with sulfonamide and halogen source was firstly investigated, which provided a facile route for the synthesis of a large variety of α-halo-β-amino ketones. The key intermediates, β-amino ketones, were obtained through tandem Meyer-Schuster rearrangement reaction of propargyl alcohols and intermolecular Michael addition of α, β-unsaturated ketones and sulfonamide. Then the in situ generated α-halo-β-amino ketones underwent the base-promoted intramolecular cyclization to give diverse acyl aziridines in a one-pot fashion. These transformations are reliable on a large scale. The high yields and convenient experimental operations make it a valuable method for the construction of α-halo-β-amino ketones and acyl aziridine derivatives.     

Preparation of partially substituted 1-halo- and 1,4-dihalo-1,3-dienes via reagent-controlled desilylation of halogenated 1,3-dienes

Depending on the desilylation reagents used, 1-halo-1,4-bis(trimethylsilyl)-1,3-butadienes afforded either 1-halo-1-trimethylsilyl-1,3-butadienes or 1-halo-4-trimethylsilyl-1,3-butadienes in excellent yields with excellent selectivity, respectively, when treated with CF3COOH or with NaOMe. These monosilylated 1,3-butadiene products could be further desilylated to generate their corresponding halobutadienes via the above reagent-controlled desilylation reaction. When 1,4-dihalo-1,4-bis(trimethylsilyl)-1,3-dienes were treated with MeONa/MeOH at room temperature, desilylation of both of the two trimethylsilyl groups took place to afford their corresponding 1,4-dihalo-1,3-dienes in excellent yields. The commonly used desilylation reagent CF3COOH did not work for these dihalobutadienes.     

The synthesis of benzofuroquinolines. IV. Some halobenzofuro[2,3-B]- and [3,2-C]quinoline derivatives

Some 8- or 9-halobenzofuro[2,3-b]quinolines ( 1a , 8-F, 8-C1, 9-F, 9-Cl) and 9-halobenzofuro[2,3-b]quinoline-11-carboxylic acid ( 1b , F, Cl) were synthesized from 6- or 7-halo-3-(2-methoxyphenyl)-2-oxo-1,2-dihydroquino-line-4-carboxylic acids ( 3 ). And, some 9-halo-11(6H)-benzofuro[2,3-b]quinolinone ( 8 , F, Cl, Br) and 2-halo-6(5H)-benzofuro[3,2-c]quinolinone ( 9 , F, Cl, Br) were synthesized from 6-halo-4-hydroxy-3-(2-methoxyphenyl)-2(1H)-quinolinone ( 7 ), and they were converted to the corresponding chlorohalobenzofuroquinolines ( 1c , 9-F, 9-C1, 9-Br, and 2 , F, Cl, Br).     

Fragmentation of carbohydrate anomeric alkoxy radicals: a new synthesis of chiral 1-halo-1-bromo compounds

The reaction of 1,2-halohydrins derived from easily available carbohydrates with (diacetoxyiodo)benzene (DIB) in the presence of bromine is a mild procedure for the synthesis of 1-deoxy-1-halo-1-bromo-alditols with one carbon less than the original carbohydrate. The reaction goes through β-fragmentation of the intermediate anomeric alkoxyl radicals. These 1-halo-1-bromo polyhydroxy compounds may be valuable synthetic intermediates in organic synthesis.     

Chemoselective 1-ethylpiperidine hypophosphite (EPHP)-mediated intermolecular radical additions of 1-deoxy-1-halo-1-iodo-alditols to electron-deficient olefins

The chemoselective radical reduction of the iodine atom in a series of 1-deoxy-1-halo-1-iodo-alditols with the 1-ethylpiperidine hypophosphite (EPHP)/AIBN system is described. EPHP is also a good chain carrier for the radical addition of gem-dihalocompounds to electron-deficient olefins. Thus, the synthesis of 4-halo-glycooctononitriles and 4-halo-glycoheptononitriles can be achieved by an intermolecular addition of the 1-deoxy-1-halo-alditol-1-yl radical intermediate to acrylonitrile.     

Synthesis of acyclic pentaalkoxyphosphoranes from tris(hexafluoroisopropoxy)dihalophosphoranes and chloral

Tris(hexafluoroisopropoxy)-bis(1-halo-2,2,2-trichloroethoxy)phosphoranes were obtained by addition of chloral to tris(hexafluoroisopropoxy)dibromo- and dichlorophosphoranes. The intermediate tris(1,1,1,3,3,3-hexafluoroisopropoxy)-1,2,2,2-tetrachloroethoxychlorophosphorane was also isolated in this reaction.V. I. Ul'yanov-Lenin Kazan State University, 420008 Kazan. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 3, pp. 683–687, March, 1992.     

A trans-stereoselective synthesis of 3-Halo-4-alkyl(aryl)-NH-azetidin-2-ones

[formula: see text] Conrotatory ring closure of 1-halo-3-aza-4-alkyl-1,3-dienes in refluxing toluene gives rise to 3-halo-4-aryl-2-azetidinones in satisfactory yields. Dehalogenation of the resulting beta-lactams by tris(trimethylsilyl)silane furnished 3-unsubstituted azetidinones, valuable intermediates in the synthesis of biologically active compounds.     

Alkoxyl radical fragmentation of 3-azido-2,3-dideoxy-2-halo-hexopyranoses: a new entry to chiral polyhydroxylated 2-azido-1-halo-1-alkenes

A new general two-step methodology for the synthesis of chiral fluoro, chloro, bromo and iodo vinyl azides from carbohydrate-derived halohydrins has been developed. The anomeric alkoxyl radical fragmentation of 3-azido-2,3-dideoxy-2-halo-pyranoses under oxidative conditions with (diacetoxyiodo)benzene and iodine gave 2-azido-1,2-dideoxy-1-halo-1-iodo-alditols, which by chemoselective dehydroiodination afforded (Z,E)-2-azido-1,2-dideoxy-1-halo-4-O-formyl-pent-1-enitols in good overall yields. Preliminary thermolysis and photochemical studies of these compounds for the synthesis of hitherto unknown disubstituted 2-halo-3-alkyl-2H-azirines have also been accomplished.     

A palladium-catalyzed multicomponent synthesis of imidazolinium salts and imidazolines from imines, acid chlorides, and carbon monoxide

A palladium-catalyzed multicomponent synthesis of imidazolinium carboxylates and imidazolines is described. The palladium catalyst [Pd(CH(R(1))N(R(2))COR(3))Cl](2), or [Pd(allyl)Cl](2), with P(t-Bu)(2)(2-biphenyl) can mediate the simultaneous coupling of two imines, acid chloride, and carbon monoxide into substituted imidazolinium carboxylates within hours under mild conditions (45 °C, 4 atm of CO). The reaction proceeds in good yield with aryl-, heteroaryl-, and alkyl-substituted acid chlorides, as well as variously functionalized imines. Imidazolines are formed via the initial generation of Mu?nchnone intermediates, followed by their cycloaddition with an in situ generated protonated imine. The addition of an amine base can intercept catalysis at Münchnone formation, which allows the subsequent cycloaddition of a second imine. The latter provides a route for the assembly of complex, polysubstituted imidazolinium carboxylates with independent control of all five substituents. The subsequent removal of the nitrogen substituent(s) provides an overall synthesis of imidazolines.     

Reaction of 5,5-dialkyl-2-halo-6-hydroxy-5,6-dihydro-1H-pyridine-3,4,4-tricarbonitriles with Morpholine

5,5-Dialkyl-2-halo-6-hydroxy-5,6-dihydro-1H-pyridine-3,4,4-tricarbonitriles reacted with morpholine in aprotic solvent to give the corresponding 3,3-dialkyl-4,5-dicyano-6-halo-2-morpholino-1,2,3,4-tetrahydropyridine-4-carboxamides, while analogous reaction in amphiprotic solvent resulted in the formation of 8,8-dialkyl-3-halo-6-oxo-2,7-diazabicyclo[3.2.1]oct-3-ene-4,5-dicarbonitriles.