We report a sustainable and metal free carbocatalyst, graphite oxide, for the synthesis of 1,5-benzodiazepines under room temperature and solvent free heating conditions.

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The anomalous high-index faces (hkl) of the mineral calaverite (Au~_xAgxTe2) measured goniometrically in the year 1931 by Goldschmidt, Palache & Peacock [Neues Jahrb. Mineral (1931), 63, 1-58] are re-interpreted and related to the wave vector q of the displacive incommensurate modulation which was recently found in the crystal structure. All crystal * Present address: Philips Research Laboratories, PO Box 80.000, NL-5600 JA Eindhoven, The Netherlands.faces (including the high-index ones) can be given four low indices (hklm), using q as a fourth basis vector. From this an almost hundred-year-old anomaly in crystal morphology is in principle solved. I. IntroductionThe present investigation started from a non-applicability of the law of rational indices to crystal growth forms of calaverite Aul_pAgpTe2 (p < 0.15) (Smith, 1902;Goldschmidt, Palache & Peacock, 1931).Classically (Bravais-Friedel) the morphology of crystals is related to the existence of a crystal lattice. This crystal lattice is even implicitly suggested by Haiiy's law of rational indices. The latter can be extended to the use of four or more rational indices in order to describe the crystal forms of modulated crystals (Janner, Rasing, Bennema & van der Linden, 1980;Dam & Janner, 1983, 1986. The fact that the number of indices can be larger than three reflects the fact that the number of fundamental periodicities can also be larger than three, which is a key concept for the understanding of crystal faces. Hence, in the description of crystal morphology one is not necessarily restricted to the three periodicities generating a three-dimensional space lattice. In the onedimensional modulated case the modulation wave vector q = aa* + fib* + yc* has to be added as a fourth basic vector to the three ones of the undistorted reciprocal-lattice unit cell: a*, b*, c*. Any crystal face of a one-dimensionally modulated crystal is then labeled by the four indices (hklm) of the corresponding face normal given by k--ha*+kb*+lc*+ mq.The use of four indices is closely related to the superspace approach as introduced for incommensurately modulated crystals by de Wolff (1977) and Janner & Janssen (1977. Indeed, the presence of fundamental periodicities in a given crystal does not mean that the structure is periodic in space. One can eventually restore the familiar lattice periodicity by embedding the crystal in a larger space, the superspace, with as many dimensions as there are fundamental periodicities. In Dam & Janner (1986) the details of this approach are explained and applied to the morphology of the modulated phases of the crystal tetramethylammonium tetrachlorozincate [(CH3)aN]2ZnCI 4. The most recent experimental result of morphological research on that compound is the observation of a roughening of a satellite orientation (hklm) upon a change of the modulation wave vector q as a function of temperature (Dam, 1985). Note that superspace embedding is necessary for a symmetry characterization in terms of Euclidean space groups, but not if that is not req...

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It is shown that the modulated phases of tetramethylammonium tetrachlorozincate, [(CH3)4N]2ZnC14, can be described by one superspace group: Pcmn(OO3")(lsi).This group is consistent not only with the properties of the diffraction pattern of the commensurate and incommensurate phases (and in particular with the corresponding space-group assignments found in the literature) but also with the crystal morphology, the latter being studied here by growth sphere experiments. The description of the morphology in terms of main and satellite faces, analogous to the description of the diffraction pattern, reveals a simple order in the crystal morphology of the different phases. Whereas the main faces remain relatively unperturbed, the position and appearance of satellite faces are directly related to the modulation wave. In fact, the evolution of the modulation wave vector can be monitored from the position of the satellite faces with respect to the main faces. Morphological extinction conditions even show compatibility with the proposed superspace group. Though the bonding structure of the satellite faces is not quite understood yet, a preliminary explanation is given in terms of a stabilized step structure.

Graphite oxide, a green metal-free carbocatalyst, has been successfully exploited for the library synthesis of biologically active pyrimidine derivatives. Reaction was carried out under solvent-free reaction conditions (SFRC) thereby reducing the application of hazardous chemicals and solvents. The present catalytic system eliminates the risk of metal contamination in the product which is viable for pharmaceutical industries and showed better catalytic activity under sustainable conditions compared to other classical catalytic systems. The catalyst, being heterogeneous in nature, can be easily recycled and reused up to nine consecutive runs without much decrease in catalytic activities thereby increasing sustainability of the procedure. Diversity in the formation of pyrimidine moieties has been exhibited with the tolerance of a large number of functional groups establishing the generality of this reaction. A few other cutting edge advantages of the present one-pot multicomponent methodology are high atom economy, low catalyst loading, milder reaction conditions, higher yield of the desired product, simple work up procedure, easy handling of the catalyst, etc. The present methodology showed good results in gram scale conditions thereby indicating its applicability in academic as well as industrial settings in the near future.

An inimitable illustration of blue-light-induced, synthesis of β-keto sulfones has been disclosed using commercially available phenylacetylenes or acetophenones as precursors and sodium sulfinates, as the sulfonyl source. Here, the synthesized...