Reactions with Tetracyanoethylene

The zwitterion (6) can react with protic solvents to produce a variety of products. Reaction with water yields a transient hydroperoxy alcohol (10) that can dehydrate to a carboxyUc acid or spHt out H2O2 to form a carbonyl compound (aldehyde or ketone, R2CO). In alcohoHc media, the product is an isolable hydroperoxy ether (11) that can be hydrolyzed or reduced (with (CH O) or (CH2)2S) to a carbonyl compound. Reductive amination of (11) over Raney nickel produces amides and amines (64). Reaction of the zwitterion with a carboxyUc acid to form a hydroperoxy ester (12) is commercially important because it can be oxidized to other acids, RCOOH and R COOH. Reaction of zwitterion with HCN produces a-hydroxy nitriles that can be hydrolyzed to a-hydroxy carboxyUc acids. Carboxylates are obtained with H2O2/OH (65). The zwitterion can be reduced during the course of the reaction by tetracyanoethylene to produce its epoxide (66). 

In reactions with tetracyanoethylene, the stereochemistry of the double bond of an enol ether is retained in the cyclobutane product when the reaction is carried out in non polar solvents. In polar solvents, cycloaddition is non stereospecific because of the longer life time of the zwitter ion. 

Dick turned up some interesting chemistry of caprolactam and its O-alkyl imino ethers. He and collaborators went on to explore the chemistry of allene, for example, its reactions with acetylene, carbon monoxide, and tetrafluo-roethylene. He did extensive work on the chemistry of cyclooctatetraene and of ferrocene. In the cyanocarbon area he collaborated on studies of the anion radical of tetracyanoethylene, that is, tetracyanoethylene bearing an extra electron. He was author or coauthor of 45 papers and 16 U.S. Patents that came out of the Central Research Department. 

R = CH3) by deprotonation of 1-methylbenzothiazolium salts (17) and were able to trap the carbene by reaction with azides to give isolable triazacyanines (18). In other examples tetracyanoethylene has been... 

Elnagdi et al. (88AP851) found that the reaction of 86 with tetracya-noethylene does not afford the expected structure 101 (X = Y = CN). Instead the hydrazones (88) (X = R = CN R = Ph) were isolated. Similarly, compounds 88 were formed upon treatment of 86 with cinnamonitrile derivatives. It was thus postulated that the reaction of these electron-poor double bonds with 86 proceeded via formation of an acyclic intermediate (e.g. 102) by reaction with 103, which then decomposes into isolable 101 by the elimination of water. In support, compounds 86 were recovered unreacted when treated with cinnamonitriles or with tetracyanoethylene in the absence of water (88AP851). 

The behavior of ruthenium derivative (333) resembles that of the iron analogue and reactions with some other electrophiles (CS2, PhNCO, tetracyanoethylene) was also studied <91JOM(406)123>. 

Isopropenylbenzofuran (124, Scheme 30) affords good yields of the adducts 123 and 125 on separate reaction with maleic anhydride and tetracyanoethylene. With but-3-en-2-one, 2-isopropenylbenzofuran (124, Scheme 31) affords the adducts 126 and 127 in a combined yield of 29%. When the crude product was dehydrogenated with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone in boiling benzene, the aromatized product 128 (6%) was obtained. It was accompanied by the dicyanodibenzofuran 129, which was found to arise from the excess diene present in the reaction mixture. A speculative mechanism is shown. 

Whereas the thermal ring-opening reaction of oxrranes and aziridines is frequently used for generation of carbonyl ylides and azomethine ylides, the analogous procedure starting with thiiranes does not produce the expected thiocarbonyl ylides (8). However, in the case of tetraaryl-substituted thiiranes, the photolytically mediated reaction with tetracyanoethylene (TCNE) is believed to occur via a single electron transfer (SET) mechanism, also involving a thiocarbonyl ylide as a likely intermediate (75,76) (Scheme 5.14). 

The reaction of o-nitrobenzaldehydes with some benzene derivatives in the presence of strong acid (H2S04, PPA) is a classical synthesis of acridinol N-oxides (373) (37BSF240) The synthesis works for benzyl alcohol, benzene, toluene and halobenzenes, but not for benzoic acid, benzonitrile, dimethylaniline, or nitrobenzene. Isoquinoline N-oxides (374) have been obtained from o-bromobenzaldoxime or the acetophenone derivative, and active methylene compounds with copper bromide and sodium hydride (77S760). The azobenzene cobalt tricarbonyl (375) reacts with hexafluorobut-2-yne to give a quinol-2-one (72CC1228), and the 3,4,5-tricyanopyridine (376) is formed when tetracyanoethylene reacts with an enaminonitrile (80S471). 

The first reference to 2-trimethylsilyloxy-l,3-butadiene (1) was a report2 of its reaction with tetracyanoethylene by Cazeau and Frainnet without mention of any experimental details. Later, Conia3 reported its synthesis in 50% yield with only a reference made to the usual House procedure4 for silyl enol ethers. The diene 1 has also been prepared using lithium diisopropylamide as base and chlorotrimethylsilane in tetrahydrofuran-ether (1 1) in yields up to 65%, but on a smaller scale.s... 

Coupling, of diazotized Ji-aminoaceto-phenone with quinone, 34, 1 of diazotized 3,5-dichloro-2-aminoben-zoic acid to give 4,4, 6,6 -tetra-chlorodiphenic acid, 31, 96 of dibromomalononitrile to tetracyanoethylene, 39, 65 of diphenyldichloromethane to tetra-phenylethylene, 31,104 Creased flask, 37, 55 Creosol, 33,17 Crotonaldehyde, 33, 15 34, 29 diethyl acetal, 32, 5 reaction with ethynylmagnesium bromide, 39, 57... 

The adduct (427), formed from 3,6-dipyridyl-l,2,4,5-tetrazine on reaction with N-methylmaleimide, gives the Diels-Alder adducts of benzo[c]furan (428) and (429) (Scheme 112) (71JA2346). When (427) was decomposed at 120 °C and 0.1 Torr, benzo[c]furan was isolated in a cold trap and characterized as a Diels-Alder adduct with tetracyanoethylene. 

Dihydrothiophenes are cyclic vinyl sulfides. They have been shown to undergo interesting, and sometimes unexpected, cycloaddition reactions. With tetracyanoethylene... 

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