Ethylene 1,1-dicyano

Dicyano-l,2,3-trithiole 2-oxide (143) has been prepared from the silver salt of 2,3-dimercaptomaleonitrile (142) and thionyl chloride (66HC(2l-i)67). Similarly, the reaction of ethylene glycol (144) with thionyl chloride gave 1,3,2-dioxathiolane 2-oxide (145), the parent compound of saturated five-membered cyclic sulfites (see Chapter 4.33). 

If the bathochromic effect of geminal dicyano substitution is assumed to be in the same range as found for ethylenic reference compounds79, from the positions of maxima in 182 and 193 the absorption of the parent triafiilvene can be estimated to appear in the region of 205—215 nm. This is in qualitative agreement with MO prediction172 that the rr -> 77 transition for methylene cyclopropene will fall near 200 nm. 

In this section we shall determine the effect of nonbonded interactions on the physical properties of related molecules. As our model compounds we will utilize difluoroethylene, a molecule having substituents bearing only lone pairs and dicyano-ethylene, a molecule bearing substituents with both filled and unfilled MO s. In particular, we focus on the three possible isomers of a disubstituted ethylene ie. the 1,1, trans-1,2- and cis- 1,2-isomers. The three possible isomers are shown below. 

The behavior described above has been verified by experiment and calculation on numerous substituted dienes and dienophiles. For example Fig. 10.13 shows results for 2°-D isotope effects on Diels-Alder reactions of 2-methyl-butadiene with cyano-ethylene and 1,1-dicyano-ethylene. The calculated and experimental isotope effects are in quantitative agreement with each other and with the results on (butadiene + ethylene). In each case the excellent agreement between calculated and observed isotope effects validates the concerted mechanism and establishes the structure of the transition state as that shown at the bottom center of Fig. 10.11 and the left side of Fig. 10.12a. 

Turro69 has reported that several alkyl ketones react with 1,2-dicyano-ethylene (12) by nucleophilic attack of the ketone (rr, n) singlet state to give oxetanes stereospecifically. Addition of diene quenchers which are known to deactivate ketone triplets do not affect the rate of oxetane formation. This... 

Anomalous behavior is exhibited by the tricarbonylruthenium complex of 1-methoxycar-bonyl-1//-azepine in that at room temperature with TCNE, perfluoropropanone or l,l-dicyano-2,2-bis(trifluoromethyl)ethylene, exo-2,5-adducts, e.g. (143), are obtained. Deuteration studies reveal that the addition is non-concerted and involves an initial electrophilic attack by the 2u--system at the uncoordinated double bond of the azepine-metal carbonyl complex <77JCS(D)204). 

Fe(cyclooctatetraene)(CO)3] reacts with TCNE to form a cycloadduct having the bicyclic structure (33) shown in equation (13).44-47 Addition is exo to the metal. Similar reactions with other electrophilic alkenes such as l,l-dicyano-2,2-bis(trifluoromethyl)ethylene have lso been observed.46... 

With a-trimethylsilyloxyvinylthiophene 144 the reactions with the olefins 165a-j work in a way similar to that with vinylfurans (Section II,D,1) [84JCR(S)218]. Only in the case of the olefin (E)-l, 2-dicyano-l, 2-bis(eth-oxycarbonyl)ethylene 165i was the corresponding primary adduct isolated. 

Arenecarbonitrile oxides add to the dicyano-ketene ethylene acetal 82 to yield 1,2,4-oxadiazoles 83 (95SC2379). The formation of the oxadiazole 86 by the action of nitronium tetrafluoroborate in acetonitrile on the ester 84 is thought to proceed by way of the a-carbonyl cation 85, which undergoes a 1,2-shift of a methyl group (95TL3039). The high-pressure reaction of nitrones with cyanides to yield 1,2,4-oxadiazolines, e.g. 87 and 88, has been reported (95SYM498). 

DBPO DBU DCC DDQ DEAD DET DIBAL-H DIPT DMAP DMB DME DMF DMPU DMSO EDDA Eu(dppm)3 Eu(fod)3 dibenzoyl peroxide 1.8- diazabicyclo [ 5.4.0] undec-7-ene dicyclohexylcarbodiimide 2.3- dichloro-5,6-dicyano-l,4-benzoquinone diethyl azodicarboxylate diethyl tartrate diisobutylaluminium hydride diisopropyl tartrate iMM-dimethylaminopyridine 3.4- dimethoxybenzyl 1.2- dimethoxyethane dimethylformamide 1.3- dimethyl-3,4,5,6-tetrahydro-2(lH)pyrimidinone dimethyl sulfoxide ethylene diammonium diacetate di(perfluoro-2-propoxypropionyl)methanato europium 6.6.7.7.8.8.8- heptafluoro-2,2-dimethyl-3,5-octanedionato... 

One of the key factors in the speedy syntheses of cfs-dicyano-ethylene-l,2-dithiolato complexes is the rapid preparation of the... 

They have also prepared mono- 147-149 and tris-crown ethers 150-152 containing the tetraazaporphyrin unit. Singly crowned porphyrazine 147 was prepared by the reaction of >15 equiv of 1,2-dicyanobenzene and 1 equiv of 33 under classic Linstead macrocyclization conditions. On the other hand, tris-crowned porphyrazine 150 was prepared by the reaction of 3 equiv of 32 and 1 equiv of l,2-dicyano-l,2-bis(l 1-hydroxyundecylthio)ethylene. Rapid complexa-tion of Ag+ was observed for 147-149, with weaker complexation of Hg2+ and Na+ observed only by MS. There was... 

MVK = methytvinytketone NQ = l,44iaphthoquinone DAC = din thylacetytene di-carboxylate FN = rn7Rs-l,2-dicyano-ethylene ACN = aciylonitrile FMI = N-phenyl-maleinimide. 

The following nitriles have been used to prepare carboxypyrazines 2-cyano-3-phenyl [NaOH/ethylene glycol/reflux (1274) or heated with H2S04/NaN02 (1024)] 3-cyano-2,5-dimethyl (NaOH/EtOH/reflux) (1015) 3-cyano-2,5-diphenyl (NaOH) (286) 2,3-dicyano [NaOH/EtOH (354) aq. KOH/EtOH (353) NajOj (357)] 2,6-dicyano (5% NaOH/10072h)(865) 23-dicyano-5,6-dimethyl(Na202) (357) 2-cyano-6-ethylthio(propylthio or phenylthio) (NaOH/EtOH/reflux) (992) 2hydrochloric acid to 2-(3 -carboxy-3 -phenylpropyl)pyrazine (731). 

Diiminosuccinonitrile (DISN) (10) reacts exothermically with ds-l,2-dimethoxy-ethylene (62) in acetonitrile to give 5,6-dicyano-2,3-dimethoxy-l,2,3,4-tetrahydro-pyrazine (63) (386, 1596). Styrene and p-halogenostyrenes reacted with DISN in acetonitrile at room temperature to form 2-amino-3-(2 -arylaziridin-r-yl)maleonitrile (64) (50-80%), whereas the more electron-rich p-methoxystyrene and 2-vinylfuran gave 5-aryl-2,3-dicyano-l,4,5,6-tetrahydropyrazine(65)(60-80%).p-Methylstyrene gave both types of products (1597). 

The situation is different with electron-poor olefins such as 1,2-dicyano-ethylene. Only the S, state of acetone forms oxetanes, and the reaction is highly stereospecific, as indicated in Scheme 24. The competing cis-trans isomerization of the olefin arises exclusively from the triplet state (Dalton et al., 1970). 

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