An efficient catalytic method for the synthesis of 3-thioindoles has been successfully developed, which uses odorless, stable, readily available crystalline Bunte salts as the sulfenylating agents, iodine as nonmetallic catalyst, and DMSO as both the oxidant and solvent. This method is practical and environmentally benign in terms of sulfur sources, catalyst, and solvent. The catalytic reaction is selective at the C3 position of indoles and compatible with a wide range of substrates, giving the desired products in good to excellent yields.
Two transition metal (Cu and Pd)-catalyzed C-S, C-N, and C-C bond cross-coupling reactions for the preparation of N-fused benzo[4,5]imidazo[2,1-b]thiazole derivatives were developed. A variety of 3-substituted and 2,3-disubstituted benzo[4,5]imidazo[2,1-b]thiazoles were efficiently and conveniently synthesized from the coupling reaction via trans-1,2-diiodoalkenes, 1H-benzo[d]imidazole-2-thiols, and halobenzenes in moderate to excellent yields.
Ice growth has attracted great attention for its capability of fabricating hierarchically porous microstructure. However, the formation of tilted lamellar microstructure during freezing needs to be reconsidered due to the limited control of ice orientation with respect to thermal gradient during in-situ observations, which can greatly enrich our insight into architectural control of porous biomaterials. This paper provides an in-situ study of solid/liquid interface morphology evolution of directionally solidified single crystal ice with its C-axis (optical axis) perpendicular to directions of both thermal gradient and incident light in poly (vinyl alcohol, PVA) solutions. Misty morphology and V-shaped lamellar morphology were clearly observed in-situ for the first time. Quantitative characterizations on lamellar spacing, tilt angle and tip undercooling of lamellar ice platelets provide a clearer insight into the inherent ice growth habit in polymeric aqueous systems and are suggested exert significant impact on future design and optimization in porous biomaterials.
A novel palladium–copper catalyzed C(sp3)–C(sp2) bond C–H activation cross-coupling reaction has been developed. A series of 9-aryl-9H-xanthenes and 9,9-diaryl-xanthenes were selectively synthesized in moderate to good yields by controlling the reaction time and temperature.
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