SHORT COMMUNICATIONSIsoindoles occupy a particular place in the chemistry of heterocyclic compounds [1,2]. Some isoindole derivatives were found to exhibit antihypertensive, antidiabetic, and antibacterial activity [3,4]. Polymeric composite materials based on isoindoles and methanoisoindoles are used in optoelectronics as fluorescent sensors and laser dyes [5,6]. Aromatic character and high reactivity of isoindoles make them convenient model substrates for theoretical studies [7].Among isoindole derivative, methanoisoindoles have been studied relatively poorly, and available data on these compounds are contradictory [7]. Lebedev et al.[4] described a procedure for the synthesis of 4-aryl-4-azatricyclo[5.2.1.0 2,6 ]deca-2,5,8-trienes ΙΙ in 62-65% yield by reaction of amines with cyclopentadiene adduct Ι with cis/trans-isomeric 2,5-dimethoxy-2,5-dihydrofurans in glacial acetic acid at 70-100°C (Scheme 1). However, we failed to reproduce this procedure. Kobayashi et al. [7] also failed to obtain compound ΙΙ under the conditions described in [4]. The authors [7] developed a four-step procedure for the synthesis of ΙΙ via reaction of aromatic amine with 3-(diethoxymethyl)bicyclo[2.2.1]hepta-2,5-diene-2-carbaldehyde (adduct of cyclopentadiene with 4,4-diethoxybut-2-ynal), followed by reduction of the products to amines and cyclization of the latter to the corresponding methanoisoindoles. However, the yields were relatively poor (18-22%).We succeeded in obtaining compound ΙΙa in 55-60% yield by treatment of adduct Ι with 2 N aqueous HCl at 75°C over a period of 0.5 h (as described in [8]) and subsequent addition of a mixture of 5 equiv of aniline and AcONa · 7 H 2 O in CHCl 3 . Presumably, initial hydrolysis of compound Ι gives intermediate dialdehyde A which then reacts with amine according to Paal-Knorr to afford compounds ΙΙ (Scheme 2). R = Ph (a), PhCH 2 (b). Scheme 2.

The alkylation of aromatic hydrocarbons with haloalkenes in the presence of acid catalysts makes it possible to obtain haloalkylaromatic compounds with a halogen atom in a strictly defi ned position in the side chain [1][2][3]. The products of this reaction are promising raw material for the preparation of diverse diffi cultly available organic substances. In this connection in extension of study [4] we investigated the dehydrohalogenation of haloalkylarenes with KOH solution in ethylene glycol in order to evaluate the opportunity of preparation of alkenylaromatic hydrocarbons of a defi nite structure.The dehydrohalogenation of [2-chloro(bromo)propan-1-yl]benzene afforded allylbenzene, (1Z)-and (1Е)-prop-1-en-1-ylbenzenes in the ratio 1 : 6 : 93.The dehydrochlorination of (1-chloropropan-2-yl) benzene led to the formation of a chromatographically pure prop-1-en-2-ylbenzene, and at the dehydrohalogenation of (1-bromo-and 1-iodopropan-2-yl)benzenes alongside the prop-1-en-2-ylbenzene the (1Е)-prop-1-en-1-ylbenzene was obtained (Scheme 1).Expectedly the (2-methyl-1-chloropropan-2-yl) benzene did not suffer the dehydrochlorination. Unexpectedly dehydroiodination also failed with the 1-(1-iodopropan-2-yl)naphthalene. We succeeded to obtain the 1-(1-prop-1-en-2-yl)naphthalene from the 1-(1-iodopropan-2-yl)naphthalene only by pyrolysis of the 1-(1-acetoxypropan-2-yl)naphthalene that was the product of iodine substitution by an acetoxy group (Scheme 2). The dehydrohalogenation of 1,4-dimethyl-2-[2-chloro(bromo)propan-1-yl]benzenes furnished the 1,4-dimethyl-2-[(1Е)-prop-1-en-1-yl]benzene in a nearly quantitative yield.For the dehydrohalogenation of the other haloalkylarenes we used the mixtures of the alkylation products of methyl-, ethyl-, and isopropylbenzenes with allyl chloride and bromide in the presence of Lewis acids. These products were mixtures of o-, m-, and p-(2-halopropan-1-yl) derivatives of alkylarenes.Dehydrohalogenation procedure. To a solution of 0.12 mol of KОН in 25 ml of di(ethylene glycol) was added 0.1 mol of haloalkylarene, and the mixture was boiled for 1.5 h. The reaction products were extracted into benzene. The extract was washed with water, benzene was distilled off, the residue was subjected to rectifi cation.From (1-chloropropan-2-yl)benzene we obtained 11.4 g (97%) of a mixture of bp 193-196°С, d 4 20 0.9068, n D 20 1.5498. (1Е)-Prop-1-en-1-ylbenzene was isolated of bp 73.5°С (20 mm Hg), d 4 20 0.9083, n D 20 1.5470. МR D 41.20, calc. 39.69. IR spectrum, ν, cm -1 : 965 s (trans-С=С), 770, 730 s (monosubstitution in benzene). The physicochemical constants were consistent with the published data [5].The dehydrohalogenation of the mixture of (2-chloropropan-1-yl)toluenes gave 12.8 g (97%) of a mixture of 1-methyl-2-[(1Е)-prop-1-en-1-yl]benzene (43-47%) and 1-methyl-3-and 1-methyl-4-[(1Е)-prop-1-

In the title compound, C18H19Cl2N3, the planes of the benzene rings subtend a dihedral angle of 77.07 (10)°. In the crystal, molecules are associated into inversion dimers via short Cl...Cl contacts [3.3763 (9) Å]. A Hirshfeld surface analysis indicates that the most important contact percentages for the different types of interactions are H...H (43.9%), Cl...H/H...Cl (22.9%), C...H/H...C (20.8%) and N...H/H...N (8.0%).

In the tile compound, C17H17Cl2N3, the dihedral angle between the benzene rings is 62.73 (9)°. In the crystal, there are no classical hydrogen bonds. Molecules are linked by a pair of C—Cl...π interactions, forming an inversion dimer. A short intermolecular HL...HL contact [Cl...Cl = 3.2555 (9) Å] links the dimers, forming a ribbon along the c-axis direction. The Hirshfeld surface analysis and two-dimensional fingerprint plots reveal that the most important contributions for the crystal packing are from H...H (45.4%), Cl...H/H...Cl (21.0%) and C...H/H...C (19.0%) contacts.

No abstract