Synthesis of some novel α-cyanoketene-n, s-acetals derived from secondary aliphatic amines and their use in pyrazole synthesis

New α-cyanoketene-N,S-acetals 2(a–g) and β-dialkylamine-α-cyanoacrylates 3(g–i) were synthesized in good to excellent yields by the reaction of ethyl 2-cyano-3,3-bis(methylthio)acrylate 1 with secondary aliphatic amines (i.e., N-methylalkyl- and N-ethylalkylamines), and pyrrolidine, in the presence of triethylamine, under reflux in ethanol, for 1–16 h, depending on the amine used. Five N-methylalkyl amines and pyrrolidine yielded exclusively mono-substituted N,S-acetals 2(a–f) in good yields. On the other hand, N-ethylbenzylamine gave a mixture of monosubstituted products including N,S-acetal 2g in 35% yield and the unexpected product ethyl 3-[benzyl(ethyl)amino]-2-cyanoacrylate 3g in 50% yield. N-Ethylcyclohexylamine and N-ethylbutylamine did not produce N,S-acetals and gave only the unexpected products ethyl 2-cyano-3-[cyclohexyl(ethyl)amino]acrylate 3h and ethyl 3-[butyl(ethyl)amino]-2-cyanoacrylate 3i in good yields. The α-cyanoketene-N,S-acetals 2(a–f), 2j, and 2k underwent cyclization with the binucleophile hydrazine in ethanol under reflux to afford substituted pyrazoles 4(a–f), 4j, and 4k in good yields

Di-n-butyl­bis­(N-ethyl-N-phenyl­dithio­carbamato-κS)tin(IV)

The title compound, [Sn(C4H9)2(C9H10NS2)2], features a tetra­hedrally coordinated SnIV atom; the dithio­carbamate ligands coordinate in a monodentate fashion, accompanied by two n-butyl chains. The non-coordinating thione S atoms are each proximate to the SnIV atom [3.0136 (7) and 2.9865 (8) Å], giving rise to distortions from the ideal geometry as evident in the wide C—Sn—C bond angle of 139.06 (12) °. In the crystal, C—H⋯S inter­actions lead to the formation of a linear supra­molecular chain along the b axis. The chains are aligned into layers by C—H⋯π inter­actions, and the layers stack along [001]. One of the ethyl groups is statistically disordered over two sets of sites

2,2'-[2,5-Bis(hexyloxy)-1,4-phenylene]dithiophene

The asymmetric unit of the title compound, C26H34O2S2, comprises one half-mol­ecule located on an inversion centre. The thio­phene groups are twisted relative to the benzene ring, making a dihedral angle of 5.30 (7)°, and the n-hexyl groups are in a fully extended conformation. In the crystal, there are short C—H(...)π contacts involving the thio­phene groups

Benzyl N0-[1-(3-pyridyl)ethylidene]-hydrazinecarbodithioate

The title compound, C15H5N2S2, crystallizes as a trans–cis conformer. The thione sulfur is in a trans position with the methyl pyridyl fragment with respect to the C—N bond but adopts a cis position with the benzyl ring across the C—S bond. The dihedral angle between the planar quinoline ring and the dithiocarbazate unit is 103.70 (1). The inclination of the dithiocarbazate unit with the benzyl group is 17.20 (1).There are strong – stacking interactions between pairs of dithiocarbazate units and also pairs of pyridine rings [3.27 (5)and 3.28 (5) A ° , respectively]. A long-distance intermolecular N—H N hydrogen bond [3.171 (2) A ° ] also stabilizes the structure

2,5-Bis(2-naphthylmethylsulfanyl)-1-thia-3,4 diazacyclopenta-2,5-diene

The title molecule, C24H18N2S3, consists of three essentially planar fragments viz. two methylnaphthalene groups and a five-membered thiadiazole ring. The dihedral angles between the two methylnaphthalene groups and the central 1-thia-3,4-diazacyclopenta-2,5-diene group are 78.9 (1) and 68.8 (1)°. In the crystal structure, - stacking interactions exist between pairs of symmetry-related naphthalene fragments with an interplanar separation of 3.35 Å. All bond lengths and angles are comparable with previous reports except that both C-S bond lengths are slightly longer than normal. In addition, the C-S-C and S-C-C bond angles appear to be smaller than normal and this could be due to the steric hindrance of the methylnaphthalene fragments

2-Quinolylmethyl N0-[1-(m-tolyl) ethylidene] hydrazinecarbodithioate

The title compound, C20H19N3S2, crystallized as a cis–trans conformer in which the quinoline ring system is cis across the C—S bond but adopts a trans geometry with respect to the C—N bond. The compound exists in the thione form with the presence of a C S bond

3,5-Dibromo-2-[2,5-dibutoxy-4-(3,5-dibromothiophen2-yl)phenyl]thiophene

The title mol­ecule, C22H22Br4O2S2, is centrosymmetric with an inversion centre located at the centre of the benzene ring. The 3,5-dibromo­thio­phene groups are twisted relative to the benzene ring, making a dihedral angle of 41.43 (9)°

Bis{S-benzyl 3-[(phen­yl)(pyridin-2-yl)methyl­idene]dithio­carbazato}zinc acetonitrile monosolvate

In the title compound, [Zn(C20H16N3S2)2]·CH3CN, two different Schiff base moieties coordinate to the central ZnII ion as tridentate N,N′,S-chelating ligands, creating a distorted octa­hedral environment [the smallest angle being 73.24 (6)° and the widest angle being 155.73 (7)°], with the two S atoms in cis positions. The dihedral angle between the mean planes of the two coordinating ligands is 83.65 (5)°. The crystal packing is consolidated by weak C—H⋯N hydrogen-bonding inter­actions