Tetrahydro-4H-thiopyran-4-one in multicomponent reactions (microreview)

Chemistry of Heterocyclic Compounds - This paper summarizes multicomponent reactions with the participation of tetrahydro-4H-thiopyran-4-one, mainly resulting in the formation of sulfur- and...     

Relative rates of Michael reactions of 2'-(phenethyl)thiol with vinyl sulfones,vinyl sulfonate esters,and vinyl sulfonamides relevant to vinyl sulfonyl cysteine protease inhibitors

[reaction: see text] The relative rates of Michael additions of 2'-(phenethyl)thiol to representative vinyl sulfonyl Michael acceptors were measured. The dependence of the reactivity of the Michael acceptor on the nature of the sulfonyl R substituent was determined in order to evaluate the effect of these substituents on the inactivation kinetics of comparably substituted vinyl sulfonyl cysteine protease inhibitors. The rates of these Michael additions vary over 3 orders of magnitude, with phenyl vinyl sulfonate esters (R = OPh) being ca. 3000-fold more reactive than N-benzyl vinyl sulfonamides (R = NHBn).     

2-Azaanthracene (microreview)

Chemistry of Heterocyclic Compounds - Microreview focuses on the main modern synthetic approaches toward 2-azaanthracene and its derivatives. These approaches are: inverse electron-demand...     

Room-temperature palladium(II)-catalyzed N-vinylation of sulfonamides and acylamides with vinyl acetate as vinyl source

Room-temperature N-vinylation of various substituted sulfonamides and acylamides with vinyl acetate was achieved for the first time with a palladium/carbene catalyst system. This reaction provides a useful method for synthesis of enamides under mild conditions.     

The reaction of chloroalkyl(vinyl)silanes with N,N-dichloro sulfonamides

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Crosslinking of poly(vinyl alcohol) using functionalized gold nanoparticles

We report on the preparation of a new class of polymer hydrogels obtained through the chemical crosslinking reaction of poly(vinyl alcohol) (PVA) and functionalized gold nanoparticles. Carboxylic group functionalized gold nanoparticles were synthesized, dispersed in a PVA matrix and allow to react with the hydroxyl groups of PVA at high temperature. FT-IR and swelling experiments carried out on the cross-linked samples confirmed that the crosslinking reaction took place. This is the first time, to our knowledge, that functionalized nanoparticles are used as chemical crosslinking agents.     

Mechanochemical reactions on poly (vinyl chloride)

This paper is concerned with molecular phenomena appearing during deformation of poly(vinyl chloride) under tensile stress conditions. By using indirect techniques (reactions with radical acceptors, with vinylic monomers, electron microscopy) the formation of free radicals, appearing as a consequence of splitting of chemical bonds, is evidenced. The amount of reacted radical acceptor or monomer was proved to be related to solution concentration and to the duration of mechanical stress.     

Grafting reactions of vinyl acetate onto poly[(vinyl alcohol)-co-(vinyl acetate)]

The grafting preference of vinyl acetate onto the methine carbon of poly(vinyl alcohol) (PVOH) versus the acetate group of poly(vinyl acetate) (PVAc) was determined as part of an attempt to prepare novel branched PVOH from partially hydrolyzed PVAc. The results showed long chain grafting on the acetate groups of the PVAc units rather than the methine carbons of the PVOH or PVAc units. Decreasing the monomer or initiator concentration decreased the molecular weight of the graft copolymer formed. Of the initiators studied, ammonium persulfate gave the largest increase in copolymer molecular weight. Both hydrolysis and reacetylation combined with gel permeation chromatography (GPC) and ¹³C-NMR of the fully hydrolyzed material were used to estimate the number and location of grafts. © 1996 John Wiley & Sons, Inc.     

Pd(II)- and Pd(0)-cocatalyzed reactions of sulfonamides with MCPs

[reaction: see text] MCPs can efficiently react with sulfonamides in the presence of Pd(0) and Pd(II) catalysts to give the corresponding ring-opened products in high yields.