Unexpected ring-closure products derived from 3-(2-allylanilino)-3-phenylacrylate esters: crystal and molecular structures of 3-acetyl-8-allyl-6-methyl-2-phenylquinolin-4-yl acetate and (2RS)-2,8-dimethyl-4-phenyl-1,2-dihydro-6H-pyrrolo[3,2,1-ij]quinolin-6-one.

The reactions of two 3-(2-allylanilino)-3-phenylacrylate esters with acetic anhydride and with strong acids has revealed a richly diverse reactivity providing a number of unexpected products. Thus, acetylation of ethyl 3-(2-allylanilino)-3-phenylacrylate, (Ia), or ethyl 3-(2-allyl-4-methylanilino)-3-phenylacrylate, (Ib), with acetic anhydride yields not only the expected acetylated esters, (II), as the major products but also the unexpected polysubstituted quinolines 3-acetyl-8-allyl-2-phenylquinolin-4-yl acetate, (IIIa), and 3-acetyl-8-allyl-6-methyl-2-phenylquinolin-4-yl acetate, (IIIb), as minor products. Subsequent reaction of the major product ethyl 2-[(2-allyl-4-methylanilino)(phenyl)methylidene]-3-oxobutanoate, (IIb), with concentrated sulfuric acid did not provide the expected 3-acetylquinoline derivative, but instead two unexpected products, namely ethyl 4-ethyl-2-phenyl-1,4-dihydroquinoline-3-carboxylate, (IV), and ethyl 3-acetyl-4-ethyl-2-phenyl-3,4-dihydroquinoline-3-carboxylate, (V), in yields of 39 and 22%, respectively. The reaction of (Ib) with Eaton's reagent gave both the quinoline (Z)-6-methyl-2-phenyl-8-(prop-1-en-1-yl)quinolin-4(1H)-one, (VI), and the unexpected tricyclic product (2RS)-2,8-dimethyl-4-phenyl-1,2-dihydro-6H-pyrrolo[3,2,1-ij]quinolin-6-one, (VII), in yields of 71 and 12%, respectively. The products (II)-(VII) have all been fully characterized spectroscopically and the crystal structures of two of the unexpected products, i.e. (IIIb) (C23H21NO3) and (VII) (C19H17NO), are reported here. The formation of compounds (IV), (V) and (VII) all require an isomerization of the initial allyl substituent, with migration of the C=C double bond from the terminal site to the internal site. In (IIIb), the two acetyl substituents are oriented such that the intramolecular distance between the two carbonyl O atoms is only 3.243 (2) Å, and in (VII), the five-membered ring adopts a twisted half-chair conformation. The molecules of compound (IIIb) are linked by two independent hydrogen bonds to form sheets built from R4(3)(20) rings and the sheets are linked by a π-π stacking interaction to form a three-dimensional framework structure. The molecules of compound (VII) are linked by a single type of C-H...O hydrogen bond to form centrosymmetric R2(2)(14) dimers. The molecules of compound (V), which crystallizes with Z' = 2, are linked by two N-H...O and two C-H...O hydrogen bonds, forming a chain of rings.

Crystal structures of five new substituted tetrahydro-1-benzazepines with potential antiparasitic activity.

Tetrahydro-1-benzazepines have been described as potential antiparasitic drugs for the treatment of chagas disease and leishmaniasis, two of the most important so-called `forgotten tropical diseases' affecting South and Central America, caused by Trypanosoma cruzi and Leishmania chagasi parasites, respectively. Continuing our extensive work describing the structural characteristics of some related compounds with interesting biological properties, the crystallographic features of three epoxy-1-benzazepines, namely (2SR,4RS)-6,8-dimethyl-2-(naphthalen-1-yl)-2,3,4,5-tetrahydro-1H-1,4-epoxy-1-benzazepine, (1), (2SR,4RS)-6,9-dimethyl-2-(naphthalen-1-yl)-2,3,4,5-tetrahydro-1H-1,4-epoxy-1-benzazepine, (2), and (2SR,4RS)-8,9-dimethyl-2-(naphthalen-1-yl)-2,3,4,5-tetrahydro-1H-1,4-epoxy-1-benzazepine, (3), all C22H21NO, and two 1-benzazepin-4-ols, namely 7-fluoro-cis-2-[(E)-styryl]-2,3,4,5-tetrahydro-1H-1-benzazepin-4-ol, C18H18FNO, (4), and 7-fluoro-cis-2-[(E)-pent-1-enyl]-2,3,4,5-tetrahydro-1H-1-benzazepin-4-ol, C15H20FNO, (5), are described. Some peculiarities in the crystallization behaviour were found, involving significant variations in the crystalline structures as a result of modest changes in the peripheral substituents in (1)-(3) and the occurrence of discrete disorder due to the molecular overlay of enantiomers with more than one conformation in (5). In particular, an interesting phase change on cooling was observed for compound (5), accompanied by an approximate fourfold increase of the unit-cell volume and a change of the Z' value from 1 to 4. This transition is a consequence of the partial ordering of the pentenyl chains in half of the molecules breaking half of the -3 symmetry axes observed in the room-temperature structure of (5). The structural assembly in all the title compounds is characterized by not only (N,O)-H...(O,N) hydrogen bonds, but also by unconventional C-H...O contacts, resulting in a wide diversity of packing.

Four related benzazepine derivatives in a reaction pathway leading to a benzazepine carboxylic acid: hydrogen-bonded assembly in zero, one, two and three dimensions.

(2R*,4S*)-Methyl 2,3,4,5-tetrahydro-1,4-epoxy-1H-benz[b]azepine-2-carboxylate, C12H13NO3, (I), and its reduction product (2R*,4S*)-methyl 4-hydroxy-2,3,4,5-tetrahydro-1H-benz[b]azepine-2-carboxylate, C12H15NO3, (II), both crystallize as single enantiomers in the space group P212121, while the hydrolysis product (2RS,4SR)-4-hydroxy-2,3,4,5-tetrahydro-1H-benz[b]azepine-2-carboxylic acid, C11H13NO3, (III), and the lactone (2RS,5SR)-8-(trifluoromethoxy)-5,6-dihydro-1H-2,5-methanobenz[e][1,4]oxazocin-3(2H)-one, C12H10F3NO3, (IV), both crystallize as racemic mixtures in the space group P21/c. The molecules of compound (IV) are linked into centrosymmetric R2(2)(10) dimers by N-H···O hydrogen bonds, and those of compound (I) are linked into chains by C-H···π(arene) hydrogen bonds. A combination of O-H···O and O-H···N hydrogen bonds links the molecules of compound (III) into sheets containing equal numbers of R4(4)(14) and R4(4)(26) rings, and a combination of C-H···π(arene) hydrogen bonds and three-centre O-H···(N,O) hydrogen bonds links the molecules of compound (II) into a three-dimensional framework structure. Comparisons are made with some related compounds.

Three closely related dibenzazepine carboxylic acids: hydrogen-bonded aggregation in one, two and three dimensions.

In the structure of (6R*,11R*)-5-acetyl-11-ethyl-6,11-dihydro-5H-dibenzo[b,e]azepine-6-carboxylic acid, C19H19NO3, (I), the molecules are linked into sheets by a combination of O-H...O and C-H...O hydrogen bonds; in the structure of the monomethyl analogue (6RS,11SR)-5-acetyl-11-ethyl-2-methyl-6,11-dihydro-5H-dibenzo[b,e]azepine-6-carboxylic acid, C20H21NO3, (II), the molecules are linked into simple C(7) chains by O-H...O hydrogen bonds; and in the structure of the dimethyl analogue (6RS,11SR)-5-acetyl-11-ethyl-1,3-dimethyl-6,11-dihydro-5H-dibenzo[b,e]azepine-6-carboxylic acid, C21H23NO3, (III), a combination of O-H...O, C-H...O and C-H...π(arene) hydrogen bonds links the molecules into a three-dimensional framework structure. None of these structures exhibits the R2(2)(8) dimer motif characteristic of simple carboxylic acids.

Four 1-naphthyl-substituted tetrahydro-1,4-epoxy-1-benzazepines: hydrogen-bonded structures in one, two and three dimensions.

(2S*,4R*)-2-exo-(1-Naphthyl)-2,3,4,5-tetrahydro-1H-1,4-epoxy-1-benzazepine, C(20)H(17)NO, (I), crystallizes with Z' = 2 in the space group P2(1); the two independent molecules have the same absolute configuration, although this configuration is indeterminate. The molecules of each type are linked by a combination of C-H...O and C-H...π(arene) hydrogen bonds to form two independent sheets, each containing only one type of molecule. (2SR,4RS)-7-Methyl-2-exo-(1-naphthyl)-2,3,4,5-tetrahydro-1H-1,4-epoxy-1-benzazepine, C(21)H(19)NO, (II), crystallizes as a true racemate in the space group P2(1)/c, and a combination of C-H...N, C-H...O and C-H...π(arene) hydrogen bonds links the molecules into sheets, each containing equal numbers of the two enantiomorphs. (2S*,4R*)-2-exo-(1-Naphthyl)-7-trifluoromethyl-2,3,4,5-tetrahydro-1H-1,4-epoxy-1-benzazepine, C(21)H(16)F(3)NO(2), (III), crystallizes as a single enantiomorph, as for (I), but now with Z' = 1 in the space group P2(1)2(1)2(1); again, the absolute configuration is indeterminate. A single C-H...π(arene) hydrogen bond links the molecules of (III) into simple chains. (2S,4R)-8-Chloro-9-methyl-2-exo-(1-naphthyl)-2,3,4,5-tetrahydro-1H-1,4-epoxy-1-benzazepine, C(21)H(18)ClNO, (IV), crystallizes as a single enantiomorph of well defined configuration, in the space group P2(1)2(1)2(1), where two independent C-H...π(arene) hydrogen bonds link the molecules into a single three-dimensional framework structure.

Four differently substituted 2-aryl-2,3,4,5-tetrahydro-1H-1,4-epoxy-1-benzazepines: hydrogen-bonded structures in one, two and three dimensions.

In (2RS,4SR)-7-chloro-2-exo-(2-chloro-6-fluorophenyl)-2,3,4,5-tetrahydro-1H-1,4-epoxy-1-benzazepine, C(16)H(12)Cl(2)FNO, (I), molecules are linked into chains by a single C-H...pi(arene) hydrogen bond. (2RS,4SR)-2-exo-(2-Chloro-6-fluorophenyl)-2,3,4,5-tetrahydro-1H-1,4-epoxy-1-benzazepine, C(16)H(13)ClFNO, (II), is isomorphous with compound (I) but not strictly isostructural with it, as the hydrogen-bonded chains in (II) are linked into sheets by an aromatic pi-pi stacking interaction. The molecules of (2RS,4SR)-7-methyl-2-exo-(4-methylphenyl)-2,3,4,5-tetrahydro-1H-1,4-epoxy-1-benzazepine, C(18)H(19)NO, (III), are linked into sheets by a combination of C-H...N and C-H...pi(arene) hydrogen bonds. (2S,4R)-2-exo-(2-Chlorophenyl)-2,3,4,5-tetrahydro-1H-1,4-epoxy-1-benzazepine, C(16)H(14)ClNO, (IV), crystallizes as a single enantiomer and the molecules are linked into a three-dimensional framework structure by a combination of one C-H...O hydrogen bond and three C-H...pi(arene) hydrogen bonds.