Mono-substituted acetonitriles, reaction with

An extensively studied and highly important 1,2,3-dithiazole - 4,5-dichloro-l,2, 3-dithiazol-l-ium chloride (Appel salt) 145 (R = Cl) - was first prepared by Appel and coworkers in 1985 by chlorination of chloroacetonitiile by sulfur monochloride in dichloromethane (1985CB1632) and it has been the most convenient procedure to date. Appel salt can be obtained also by prolonged chlorination of acetonitrile itself, or by the sulfur monochloride reaction with ethylamine the yields and experimental conditions were not disclosed (1985PS277). Recently, a series of mono-substituted acetonitriles were converted to 5-substituted-4-chloro-l,2,3-dithiazolium chlorides 145 (1999CC531,... 

Iodine in combination with [bis(acyloxy)iodo]arenes is a classical reagent combination for the oxidative iodination of aromatic and heteroaromatic compounds [99], A typical iodination procedure involves the treatment of electron-rich arenes with the PhI(OAc)2-iodine system in a mixture of acetic acid and acetic anhydride in the presence of catalytic amounts of concentrated sulfuric acid at room temperature for 15 min [100,101]. A solvent-free, solid state oxidative halogenation of arenes using PhI(OAc)2 as the oxidant has been reported [102]. Alkanes can be directly iodinated by the reaction with the PhI(OAc)2-iodine system in the presence of f-butanol under photochemical or thermal conditions [103]. Several other iodine(in) oxidants, including recyclable hypervalent iodine reagents (Chapter 5), have been used as reagents for oxidative iodination of arenes [104-107]. For example, a mixture of iodine and [bis(trifluoroacetoxy)iodo]benzene in acetonitrile or methanol iodinates the aromatic ring of methoxy substituted alkyl aryl ketones to afford the products of electrophilic mono-iodination in 68-86% yield [107]. 

CP2C0 catalyses the condensation of acetylene and mono-substituted acetylenes (but not di-substituted acetylenes) with nitriles at 150° to give 30-70% yields of substituted pyridines [WakatsuM Yamazaki Synthesis 26 1976], This synthesis has been applied successfully in a 2+2+2 cycloaddition reaction between di(trimethylsilyl)propargyl ether and acetonitrile to prepare a pyridine intermediate whieh was used to obtain pyridoxine (vitamin Be) [Greiger et al. Helv Chim Acta 67 1274 1984. ... 

The reaction of trimethyl and triphenylstannyl potassium with mono- and di-substituted enones in acetonitrile as solvent led in nearly quantitative yields either to a mixture of diastereomers or to a pure diastereomer of /S-stannylketones (Scheme 41)109. There was experimental support for the existence of a SET mechanism, i.e. partial or total inhibition of the reaction by addition of a free radical scavenger (galvinoxyl) or a radical anion scavenger (p-dinitrobenzene). The possibility of a SET depends on the one-electron donor ability of the nucleophile and the electron acceptor ability of the ketone. These reactions are stereoselective. 

The fluorination of quinoline was performed in a microstructured reactor operated in the annular-flow regime, which contained one microchannel with two consecutive feeds for gas and liquid [311,312]. The role of the solvent was large. The reaction was totally unselective in acetonitrile and gave only tarlike products. With formic acid, a mixture of mono- and polyfluorinated products besides tar was formed. No tar formation was observed with concentrated sulfuric acid as solvent at 0-5 °C. In this way, a high selectivity of about 91% at medium conversion was achieved. Substitution was effective only in the electron-rich benzenoid core and not in the electron-poor pyridine-type core. The reactivity at the various positions in the quinoline molecule is 5 > 8 > 6 and thus driven by the vicinity to the heteroatom nitrogen that corresponds to the electrophilic reactivity known from proton/deuterium exchange studies in strong acid media. 

Alkyl and aryl A -substituted 1,2,5-thiadiazolidine-1,1-dioxides 316 are synthesized in good yield from the reaction of sulfuryl chloride with 2-chloroethylamine. 2-Chloroethylamine hydrochloride is heated at 80°C with sulfuryl chloride in acetonitrile, and corresponding mono(chloroalkyl)sulfamyl chloride 314 is then extracted with diethyl ether to separate from unreacted amine hydrochloride. This ether solution is added to a solution of primary amine, and the resultant A -aryl (chloroalkyl)sulfamide 315 is treated with potassium carbonate in DMSO to afford A -substituted 1,2,5-thiadiazolidine-l,1-dioxides 316 <03TL5483>. 

Arakawa and coworkers [45] developed the on-line photoreaction cell depicted in Figure 5.3 and performed a series of studies on the detection of reaction intermediates in photosubstitution and photooxidation of Ru(II) complexes. The photosubstitution of Ru(bpy)2B [bpy = 2,2 -bipyridine B = 3,3 -dimethyl-2,2 -bipyridine (dmbpy) or 2-(aminomethyl)pyridine (ampy)] was studied in acetonitrile and pyridine. Irradiation of Ru(bpy)2B and related complexes yields a charge-transfer excited species with an oxidized Ru center and an electron localization on the bpy moiety. The excited-state complex underwent ligand substitution via a stepwise mechanism that includes ant] bidentate ligand (Scheme 5.6). Photoproducts such as Ru(bpy)2S2 (S = solvent molecule) and intermediates with a monodentate (mono-hapfo-coordination) B ligand, Ru(bpy)2BS, and Ru(bpy)2BSX+ (X=C10/, PF ) were detected. Other studies also identified photo-oxidized products of several mixed-valence Ru(II) complexes upon irradiation (7i> 420 nm) [31b, 46]. 

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