Keywords: Sulfur-nitrogen heterocycles / Materials science / Liquid crystals / Radicals / Fused-ring systems 3-Amino-1H-indene-2-carbonitrile and 2-amino-3H-indene-1-carbonitrile reacted with SCl 2 , iBu 3 N and NCS to give benzocyclopenta[1,2,6]thiadiazines, and whilst 2-aminocyclopent-1-enecarbonitrile gave, under the same conditions, a cyclopenta[1,2,6]thiadiazine, its reaction with mixtures of S 2 Cl 2 , SCl 2 and iBu 3 N under different conditions gave, selectively, an isothiazolo [3,4-d]

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The first multicomponent coupling of isocyanides, α,β-unsaturated carbonylic compounds and dienophiles, based on the trapping of unstable intermediate 2-aminofurans, is described. This novel tandem [4 + 1]-[4 + 2] cycloaddition is efficiently catalysed by yttrium triflate and constitutes an operationally simple and highly convergent approach to a variety of polysubstituted anilines. Moreover, this methodology permits the use of tert-butylisocyanide as a convertible isocyanide to yield directly N-unprotected anilines in the same pot.

Indene and cyclopentene enaminonitriles were reacted with SCl2, iBu3N and NCS to give the first cyclopenta[1,2,6]thiadiazines that showed unusual characteristics, one as a NIR dye and another as a liquid crystal.

Several new liquid-crystalline indene and pseudoazulene systems are reported. These molecules give rise to either columnar hexagonal mesophases and/or columnar plastic phases. The unique nature of these compounds stems from their non-classical discotic structure. Although the molecules have rigid aromatic cores, they lack terminal tails and instead the polarizable atoms (S, halogens) or polar groups (CN, CO) act as unusual soft parts. On the basis of many structurally related materials, we conclude that for this type of compound molecular stacking in the solid state is a prerequisite for the appearance of a columnar mesophase, although other intermolecular interactions within the layers are also important in establishing liquid-crystalline order. The behavior reported for these mesomorphic molecules opens up new possibilities in the search for related molecular interactions that might be useful for the construction of supramolecular architectures with particular properties.

The irradiation with UV light of a number of 1,2-diaryl-1-tosylstilbenes, in the presence of base, leads to the corresponding phenanthrenes and heterocyclic analogues. These results are consistent with a mechanism involving the base-induced elimination of p-toluenesulfinic acid from an intermediate 9-tosyl-4a,4b-dihydrophenanthrene, formed by photochemical cyclization of the starting 1,2-diaryl-1-tosylstilbenes. [reaction: see text]

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Heterocyclic enols are used for the first time as acid components in an Ugi-type multicomponent condensation. For that purpose, we have chosen enols containing a Michael acceptor, in order to facilitate an irreversible rearrangement of the primary Ugi adduct. The new four-component process leads readily and efficiently to heterocyclic enamines containing at least six elements of diversity.