Bromine In Dichloromethane Research Articles

Synthesis, structure and non-covalent interactions of 5-methyl-2,3-dihydrothiazolo[2,3-<i>b</i>]thiazolium halides

2,3-Dihydrothiazolo[2,3- b ]thiazolium iodides and bromide were obtained for the first time by the cyclization of corresponding metallyl- and propinylsulfanyl derivatives of 1,3-thiazole with iodine and bromine in dichloromethane without heating and the use of strong acids. The structure of the obtained compounds was studied by 1H, 13C{1H} NMR spectroscopy. Structure of the 3-iodomethyl-3,5-dimethyl-2,3-dihydrothiazolo[2,3- b ][1,3]thiazolium heterocyclic system is characterized by the X-ray analysis. The bonding in the heterocyclic system and non-covalent cation-anion interactions are analyzed on the basis of quantum chemical calculations with periodic boundary conditions; I···S chalcogen bond is discussed.

Reactions of 4-Propargylsulfanylquinazoline with Bromine and Iodine

Cyclization of 4-propargylsulfanylquinazoline under the action of iodine gave 3-iodomethyl[1,3]thiazolo[3,2-c]-quinazolinium triiodide, which is reduced with sodium iodide to form 3-methyl[1,3]thiazolo[3,2-c]quinazolinium iodide. The reaction with bromine in dichloromethane leads to the formation of 3-bromomethyl[1,3]thiazolo-[3,2-c]quinazolinium bromide, and in acetic acid—2-(2-aminophenyl)-4-dibromomethyl-1,3-thiazole hydrobromide.

Functiaonalization of 2-(1-Cyclohexen-1-yl)aniline Derivatives

The reaction of 2-(1-cyclohexen-1-yl)aniline and -6-methylaniline with phthalic anhydride has afforded 2-(2-cyclohex-1-en-1-ylphenyl)- and 2-(2-cyclohex-1-en-1-ylphenyl)-6-methylphenyl)-1H-isoindole-1,3(2H)-diones. The reaction of the obtained isoindole-1,3-diones with bromine in dichloromethane in the presence of sodium bicarbonate has led to the formation of the product of pseudo-allylic halogenation. Replacement of the halogen atom by methoxy group has been performed by keeping 2-[2-(6-bromocyclohex-1-en-1-ylphenyl)-6-methylphenyl)]-1H-isoindole-1,3(2H)-dione in a methanolic solution in the presence of NaHCO3. The reaction of 2-(2-cyclohex-1-en-1-yl-6-methylphenyl)-1H-isoindole-1,3(2H)-dione with molecular bromine in the presence of methanol has given a co-halogenation product, whereas the dibromination product has been obtained in the presence of octyl alcohol.

Synthesis and Characterization of Alkylamine-Functionalized Si(111) for Perovskite Adhesion With Minimal Interfacial Oxidation or Electronic Defects.

We investigated synthetic strategies for the functionalization of Si(111) surfaces with organic species containing amine moieties. We employed the functionalized surfaces to chemically "glue" perovskites to silicon with efficient electron transfer and minimal oxidation leading to deleterious recombination at the silicon substrate. A two-step halogenation-alkylation reaction produced a mixed allyl-methyl monolayer on Si(111). Subsequent reactions utilized multiple methods of brominating the allyl double bond including reaction with HBr in acetic acid, HBr in THF, and molecular bromine in dichloromethane. Reaction with ammonia in methanol effected conversion of the bromide to the amine. X-ray photoelectron spectroscopy (XPS) quantified chemical states and coverages, transient-microwave photoconductivity ascertained photogenerated carrier lifetimes, atomic force microscopy (AFM) quantified perovskite-silicon adhesion, and nonaqueous photoelectrochemistry explored solar-energy-conversion performance. The HBr bromination followed by the amination yielded a surface with ∼10% amine sites on the Si(111) with minimal oxide and surface recombination velocity values below 120 cm s-1, following extended exposures to air. Importantly, conversion of amine sites to ammonium and deposition of methylammonium lead halide via spin coating and annealing did not degrade carrier lifetimes. AFM experiments quantified adhesion between perovskite films and alkylammonium-functionalized or native-oxide silicon surfaces. Adhesion forces/interactions between the perovskite and the alkylammonium-functionalized films were comparable to the interaction between the perovskite and native-oxide silicon surface. Photoelectrochemistry of perovskite thin films on alkylammonium-functionalized n+-Si showed significantly higher Voc than n+-Si with a native oxide when in contact with a nonaqueous ferrocene+/0 redox couple. We discuss the present results in the context of utilizing molecular organic recognition to attach perovskites to silicon utilizing organic linkers so as to inexpensively modify silicon for future tandem-junction photovoltaics.

Synthesis and Reactions of Triptycene‐Derived Bromocalix[5]arenes: Conformational Transformation from Cone to 1,2‐Alternate

AbstractTriptycene‐derived p‐dibromocalix[5]arene was synthesized by a fragment‐coupling approach, whereas treatment of the triptycene‐derived calix[5]arene containing three p‐tert‐butyl phenol groups and a 1,8‐dimethoxytriptycene moiety with excess bromine in dichloromethane at room temperature produced triptycene‐derived p‐pentabromocalix[5]arene directly. Methyl etherification and Suzuki coupling reactions were then carried out. As a result, a series of triptycene‐derived calix[5]arene derivatives in fixed cone and 1,2‐alternate conformations were obtained. Moreover, conformation transformations of triptycene‐derived calix[5]arenes from cone to 1,2‐alternate forms could also be achieved.

Syntheses and Structures of 10‐Trimethylelement‐Substituted 1,8‐Dichloroanthracenes

1,8-Dichloroanthracenes bearing EMe3 substituents at the 10-position (E = Si, Ge, Sn) have been synthesised by salt elimination reactions. The key compound, 10-bromo-1,8-dichloroanthracene (2), was quantitatively obtained by conversion of 1,8-dichloroanthracene with elemental bromine in dichloromethane. The EMe3-substituted anthracene compounds 1,8-dichloro-10-(trimethylsilyl)- (3), 1,8-dichloro-10-(trimethylgermyl)- (4) and 1,8-dichloro-10-(trimethylstannyl)anthracene (5) were completely characterised by multinuclear NMR spectroscopy and mass spectrometry. Their molecular structures in the crystalline state were analysed by X-ray diffraction experiments and compared with the crystal structure of 10-tert-butyl-1,8-dichloroanthracene (1). It was found that the level of deformation of the anthracene backbone continuously increases along the series of anthracene substituents SnMe3 < GeMe3 < SiMe3 < CMe3. Owing to the good agreement of experimental structural parameters with the results of quantum chemical calculations, the molecular deformations can be regarded as inherent molecular properties.

ChemInform Abstract: Improved Synthesis of 1‐Bromo‐3‐buten‐2‐one.

Abstract A convenient procedure for the synthesis of 1-bromo-3-buten-2-one, 4, from commercially available 2-ethyl-2-methyl-1,3-dioxolane, 1, is described. The procedure involves three reaction steps: (1) The acetal 1 is converted to 2-(1-bromoethyl)-2-bromomethyl-1,3-dioxolane, 2, by reacting 1 with elemental bromine in dichloromethane to yield 98% of 2. (2) Dehydrobromination of 2 with potassium tert-butoxide in tetrahydrofuran gives 2-bromomethyl-2-vinyl-1,3-dioxolane, 3, in 84–93% yield. (3) Removal of the acetal protection from 3 by formolysis for 6–10 h afforded 1-bromo-3-buten-2-one, 4, in 85–94% yield. A more rapid method is acid hydrolysis of 3 under microwave activation (100 °C, 8–10 min), by which 4 was obtained in 75% yield. Full experimental details are given.

Improved Synthesis of 1-Bromo-3-buten-2-one

A convenient procedure for the synthesis of 1-bromo-3-buten-2-one, 4, from commercially available 2-ethyl-2-methyl-1,3-dioxolane, 1, is described. The procedure involves three reaction steps: (1) The acetal 1 is converted to 2-(1-bromoethyl)-2-bromomethyl-1,3-dioxolane, 2, by reacting 1 with elemental bromine in dichloromethane to yield 98% of 2. (2) Dehydrobromination of 2 with potassium tert-butoxide in tetrahydrofuran gives 2-bromomethyl-2-vinyl-1,3-dioxolane, 3, in 84–93% yield. (3) Removal of the acetal protection from 3 by formolysis for 6–10 h afforded 1-bromo-3-buten-2-one, 4, in 85–94% yield. A more rapid method is acid hydrolysis of 3 under microwave activation (100 °C, 8–10 min), by which 4 was obtained in 75% yield. Full experimental details are given.

Reduction of 5-(bromomethyl)-1-pyrrolinium bromides to 2-(bromomethyl)pyrrolidines and their transformation into piperidin-3-ones through an unprecedented ring expansion-oxidation protocol

3,3-Dialkyl-5-(bromomethyl)-1-pyrrolinium bromides, prepared via bromocyclization of N-(2,2-dialkyl-4-pentenylidene)amines by means of bromine in dichloromethane, were reduced to 4,4-dialkyl-2-(bromomethyl)pyrrolidines for the first time using borane dimethyl sulfide in dichloromethane. Furthermore, the latter 2-(bromomethyl)pyrrolidines were transformed into the corresponding piperidin-3-ones through an unprecedented ring expansion-oxidation protocol in dimethylsulfoxide in the presence of potassium carbonate. Reduction of 5,5-dialkylpiperidin-3-ones by means of sodium borohydride in methanol afforded 5,5-dialkyl-3-hydroxypiperidines in good yields.

Novel Synthesis of cis-3,5-Disubstituted Morpholine Derivatives

1-tert-Butyl-2-(allyloxymethyl)aziridine has been transformed for the first time diastereoselectively into cis-3,5-di(bromomethyl)-4-tert-butylmorpholine via an electrophile-induced ring closure using bromine in dichloromethane. The latter morpholine has been used as a substrate for the synthesis of the corresponding 3,5-di(methoxymethyl)morpholine and 3,5-di(cyanomethyl)morpholine upon nucleophilic displacement of both bromo atoms. Further evaluation of this protocol toward the synthesis of 4-arylmethyl- and 4-alkylmethyl-3,5-di(bromomethyl)morpholines showed that the premised cyclization of the corresponding 2-(allyloxymethyl)aziridines into 3,5-di(bromomethyl)morpholines only proceeded well for the N-neopentylmorpholine, which was subsequently transformed into a 3-oxa-7-thia-9-azabicyclo[3.3.1]nonane derivative. Also, in some other cases, the desired 3,5-di(bromomethyl)morpholines were isolated in low yields and transformed into the corresponding 3,5-di(cyanomethyl)morpholines.

Electrophile-Induced Ring Expansions of β-Lactams toward γ-Lactams

[reaction: see text] An efficient and straightforward route toward 3,4-cis-4-isopropenylazetidin-2-ones was developed from 4-(1-chloroalkyl)azetidin-2-ones. Starting from the latter beta-lactams, a new synthesis of pyrrolidin-2-ones was achieved. When 4-isopropenylazetidin-2-ones were treated with bromine in dichloromethane, diastereoselective electrophile-induced ring expansions toward 5-bromopyrrolidin-2-ones were performed. Further oxidation of 3-benzyloxypyrrolidin-2-ones with bromine toward 3-bromopyrrolidin-2-ones was also established. When 4-isopropenyl-beta-lactams were added to a mixture of NBS and TMSN(3), 5-azidopyrrolidin-2-ones were obtained in moderate to high yields.

The Addition of Bromine to 1,2-Diphenylethene

We investigated the reaction of (Z)-1,2-diphenylethene (cis-stilbene) with various brominating reagents and solvents following directions in standard organic chemistry manuals. We were particularly interested in learning which combination of brominating reagent and solvent gave the best yield of (d,l)-1,2-dibromo-1,2-diphenylethane without the formation of significant amounts of meso-1,2-dibromo-1,2-diphenylethane, which is essentially the sole product from the reaction of bromine with (E)-1,2-diphenylethene (trans-stilbene). Based on the results from the standard preparatory methods, some permutations of solvent and brominating reagent were tried. Using pyridinium bromide perbromide in either glacial acetic acid or dichloromethane gave high (about 80%) yields of the d,l product from (Z)-1,2-diphenylethene. Bromine in glacial acetic acid gave 66% of the d,l product and 20% of the meso product from (Z)-1,2-diphenylethene. However, bromine in dichloromethane gave about equal amounts of the two dibromo products. The various combinations tried could be used in an introductory organic chemistry laboratory to illustrate how changing solvents or reagents affects product formation. For an advanced organic chemistry laboratory, the students could carry out the various combinations and then be asked to provide an explanation for the results.

Reactivity of dioxoosmium(VI) porphyrins toward arylhydrazine. Isolation of hydrazidoosmium and amidoosmium porphyrins.

Reactions of dioxoosmium(VI) porphyrins [Os(VI)(Por)O(2)] with excess 1,1-diphenylhydrazine in tetrahydrofuran at ca. 55 degrees C for 15 min afforded bis(hydrazido(1-))osmium(IV) porphyrins [Os(IV)(Por)(NHNPh(2))(2)] (1a, Por = TPP (meso-tetraphenylporphyrinato dianion); 1b, Por = TTP (meso-tetrakis(p-tolyl)porphyrinato dianion)), hydroxo(amido)osmium(IV) porphyrins [Os(IV)(Por)(NPh(2))(OH)] (2a, Por = TPP; 2b, Por = TTP), and bis(hydrazido(2-))osmium(VI) porphyrin [Os(VI)(Por)(NNPh(2))(2)] (3c, Por = TMP (meso-tetramesitylporphyrinato dianion)). The same reaction under harsher conditions (in refluxing tetrahydrofuran for ca. 1 h) gave a nitridoosmium(VI) porphyrin, [Os(VI)(Por)(N)(OH)] (4b, Por = TTP). Oxidation of 1a,b with bromine in dichloromethane afforded bis(hydrazido(2-)) complexes [Os(VI)(TPP)(NNPh(2))(2)] (3a) and [Os(VI)(TTP)(NNPh(2))(2)] (3b), respectively. All the new osmium porphyrins were identified by (1)H NMR, IR, and UV-vis spectroscopy and mass spectrometry; the structure of 2b was determined by X-ray crystallography (Os-NPh(2) = 1.944(6) A, Os-OH = 1.952(5) A).

Reaction of 4,5‐Dihydro‐1H‐pyrazole‐3,5,5‐tricarboxylic Acids Esters with Halogens.

Esters of 4-R-4,5-dihydro-1H-pyrazole-3,5,5-tricarboxylic acids with chlorine yield esters of 4-R-5-chloro-4,5-dihydro-3H-pyrazole-3,3,5-tricarboxylic acids that at thermolysis provide the esters of the corresponding 2-chlorocyclopropanetricarboxylic acid. The same esters react with bromine in dichloromethane at room temperature to give a mixture of esters of the corresponding 1H-pyrazole-3,5-dicarboxylic acids and 5-bromo-4,5-dihydro-3,3,5-tricarboxylic acids. From 5,5-diethyl 3-methyl 4,5-dihydro-1Hpyrazole-3,5,5-tricarboxylate and N-iodosuccinimide or a system iodine-silver trifluoroacetate we obtained 1,1-diethyl 2-methyl 2-iodocyclopropane-1,1,2-tricarboxylate.

Reaction of 4,5-Dihydro-1H-pyrazole-3,5,5-tricarboxylic Acids Esters with Halogens

Esters of 4-R-4,5-dihydro-1H-pyrazole-3,5,5-tricarboxylic acids with chlorine yield esters of 4-R-5-chloro-4,5-dihydro-3H-pyrazole-3,3,5-tricarboxylic acids that at thermolysis provide the esters of the corresponding 2-chlorocyclopropanetricarboxylic acid. The same esters react with bromine in dichloromethane at room temperature to give a mixture of esters of the corresponding 1H-pyrazole-3,5-dicarboxylic acids and 5-bromo-4,5-dihydro-3,3,5-tricarboxylic acids. From 5,5-diethyl 3-methyl 4,5-dihydro-1Hpyrazole-3,5,5-tricarboxylate and N-iodosuccinimide or a system iodine-silver trifluoroacetate we obtained 1,1-diethyl 2-methyl 2-iodocyclopropane-1,1,2-tricarboxylate.

Reactivity of dioxoruthenium(VI) porphyrins toward amines. Synthesis and characterization of bis(arylamine)ruthenium(II), bis(arylamido)- and bis(diphenylamido)ruthenium(IV), and oxo(tert-butylimido)ruthenium(VI) porphyrins.

Reactions of dioxoruthenium(VI) porphyrins, [Ru(VI)O2(Por)], with p-chloroaniline, trimethylamine, tert-butylamine, p-nitroaniline, and diphenylamine afforded bis(amine)ruthenium(II) porphyrins, [Ru(II)(Por)(L)2] (L-p-ClC6H4NH2, Me3N, Por=TTP, 4-Cl-TPP; L=tBuNH2, Por = TPP, 3,4,5-MeO-TPP, TTP, 4-Cl-TPP, 3,5-Cl-TPP) and bis(amido)ruthenium(IV) porphyrins, [Ru(IV)(Por)(X)2] (X=p-NO2C6H4NH, Por=TTP, 4-Cl-TPP; X = Ph2N, Por = 3,4,5-MeO-TPP, 3,5-Cl-TPP), respectively. Oxidative deprotonation of [Ru(II)(Por)(NH2-p-C6H4Cl)2] in chloroform by air generated bis(arylamido)ruthenium(IV) porphyrins, [RuIV(Por)(NH-p-C6H4Cl)2] (Por=TTP. 4-Cl-TPP). Oxidation of [RuII(Por)-(NH2tBu)2] by bromine in dichloromethane in the presence of tert-butylamine and traces of water produced oxo(imido)ruthenium(VI) porphyrins, [RuVI-O(Por)(NtBu)] (Por=TPP, 3,4,5-MeO-TPP, TTP, 4-Cl-TPP, 3,5-Cl-TPP). These new classes of ruthenium complexes were characterized by 1H NMR, IR, and UV/visible spectroscopy, mass spectrometry, and elemental analysis. The structure of [Ru(IV)(TTP)(NH-p-C6H4Cl)2 . CH2Cl2 was determined by X-ray crystallography. The Ru-N bond length and the Ru-N-C angle of the Ru-NHAr moiety are 1.956(7) A and 135.8(6) degrees, respectively.

Tetraphenylphosphonium-ikosioctabromooctaantimonat(III), (PPh4)4Sb8Br28 / Tetraphenylphosphonium Ikosioctabromooctaantimonate(III), (PPh4)4Sb8Br28

The title compound was obtained by the reaction of PPh4Br, Sb2Se3, and bromine in dichloromethane. Its crystal structure was determined by X-ray diffraction. Crystal data: a = 1249.1(2), b = 1307.8(2), c = 2152.3(4) pm, α = 102.93(2), β = 100.83(2), γ = 100.42(2)°, Z = 2, triclinic, space group P1̄. (PPh4)4Sb8Br28 is isotypic with (PPh4)4Sb8I28. The Sb8Br28 4- ion can be taken as the association product of eight SbBr3 molecules with four Br− ions. Each Sb atom has a distorted octahedral coordination with three shorter (252 to 274 pm) and three longer (300 to 353 pm) Sb-Br bonds. The octahedra share common edges in two parallel rows of four octahedra each. The arrangement of the 28 bromine atoms corresponds to a section of a closest packing of spheres.

Stereoselective Synthesis of 4,5-Dihydro-1,3-thiazole and 4H-5,6-Dihydro-1,3-thiazine Derivatives

Abstract 4-Bromomethyl-4,5-dihydro-1,3-thiazoles and 5-bromo-4H-5,6-dithydro-1,3-thiazines were synthesized by intramolecular cyclization of allylthioimidates by the reaction with N-bromosuccinimide (NBS) or bromine in dichloromethane at room temperature.

1,2-bis-Dipyrrinon-9-yl-ethene ? a novelb-homo-verdian chromophore: the reaction of 9-methyl-10H-dipyrrin-1-ones with bromine

Upon treatment of 9-methyl-10H-dipyrrin-1-ones with bromine in dichloromethane, red bile pigment derivatives were obtained in moderate yields. They were structurally assigned as 1,2-bis-dipyrrinon-9-yl-ethenes, which are examples of the hitherto unknownb-homo-verdins. In addition, the correspondingmeso-biliverdins-XIIIα could be isolated from the reaction mixture. The mechanistic aspects of the reaction are discussed.

Synthesis and characterization of some amine complexes of bromocarboxyboranes and bromo(methoxycarbonyl)boranes

Amine-carboxyboranes [A.BH 2COOH; A = Me 3N, Et 3N, quinuclidine (Q)] are readily decarbonylated with bromine in dichloromethane to produce amine-dibromoboranes (A.BHBr 2). The formation of A.BHBr 2 is explained by fast loss of CO from the acid bromides A.BH(Br)COBr generated because of the action of HBr. In proton-acceptor solvents (such as H 2O), however, only substitution takes place giving a chiral boron atom containing A.BH(Br)COOH and/or A.BBr 2COOH. Also, bromocarboxyborane complexes can be prepared easily using bromination with N-bromosuccinimide (NBS). The products are rather stable in water under acidic conditions but bases induce fast decarbonylation followed by complete decomposition. Amine(methoxycarbonyl)boranes A.BH 2COOMe (A = Me 3N, Et 3N and Q) are conveniently synthesized, with good yields, in methanol by treatment with a cation exchange resin (H +) as a catalyst. The bromo derivatives A.BH 2- nBr n COOMe ( n = 1, 2) have been prepared by treatment of amine complexes of BH 2COOMe with bromine or NBS, or by esterification of the bromocarboxylic derivatives. In addition, these bromo compounds can be readily obtained in a one-pot reaction from A.BH 2COOH with bromine; when esterification proceeds unexpectedly fast in parallel with the bromination. The structures of the new derivatives were substantiated by elemental analyses and IR, UV, 1H NMR and 11B NMR spectroscopic methods.