Dicyanomethylene derivatives

A series of symmetrical and unsymmetrical active methylene compounds was reacted with salt 20 to give 5-alkylydene-l,2,3-dithiazoles 83 <1999T9651>. More surprisingly, tetracyanoethylene oxide gives under these conditions dicyanomethylene derivative 42 (Scheme 8) <1998J(P1)2505>. 

The dicyanomethylene derivatives (362 X = O, S) react with phenylisothiocyanate yielding the products (363 X = O) (70% yield) and (363 X = S) (76% yield) <87KGS989>. These reactions are examples of transformations of the general type (300) - (290). With phenylisocyanate the reaction takes a different course and products (364) are obtained (Scheme 3). 

In the same year, Heller et al.3 reported a new kind of photochromic compound - dicyanomethylene derivatives of fulgide. According to the nomenclature system of the International Union of Pure and Applied Chemistry (IUPAC), they should be named as 5-dicyanomethylene-tetrahydrofuran-2-one derivatives, as shown in formula 8. 

FULGIMIDE, ISOFULGIMIDE, FULGENATE, FULGENOID, AND DICYANOMETHYLENE DERIVATIVES OF FULGIDES... 

Another dicyanomethylene derivative of fulgide 81 was also reported. On irradiation with white light, the purple compound 81 underwent an intramolecular [4 + 4] photocyclization reaction to give colorless adducts, which underwent the reverse reaction thermally or photochemically.35 The results demonstrated that molecular modification of fulgide molecules can significantly affect the photochromic properties of fulgide family compounds. 

A microwave-assisted one-pot three-component procedure for the condensation of ninhydrin with a phenylenediamine and malononitrile under solvent-free conditions using a catalytic amount of DMSO has been reported by Mohammadizadeh and co-workers [131] to obtain the corresponding 2-(indenoquinoxalin-ll-ylidene)mal-ononitriles 95. (Scheme 72) Further, this one-pot procedure has been extended for the preparation in good yields of dicyanomethylene derivatives 96 of tryptanthrin when potassium carbonate was used as a base (Scheme 73). 

A synthesis of electrochemically amphoteric TTFAQ-ct-A derivatives 917 and 918 (TTFAQ = 9,10-bis(l,3-dithiol-2-ylidene)-9,10-dihydroanthracene, ct = saturated spacer, A = polynitrofluorene acceptor) involved esterification of the acid chloride 916 with the hydroxymethyl-substituted TTFAQ derivative 915 in pyridine. To increase acceptor properties, 917 was converted into the dicyanomethylene derivative 918 by reaction with malononitrile in DMF (Scheme 138) <2002JA14227>. 

The dicyanomethylene substituent as well as its ester analog can cause a substantial shift of the tautomeric equilibrium in the pyrimidine moiety. Dicyanomethylene derivatives and their ester analogs 38 were prepared (1988GEP249020, 1988GEP249021, 1988GEP249022) by reactions of compounds 35 successively with (di)cyanoketene dithioacetal followed by cyclization of intermediate 39 in the presence of bases. 

Flavones and their thia anologs (282) undergo Knoevenagel condensation with malonodinitrile to give the corresponding 4,4-dicyanomethylene derivatives (283). These compounds give ready access to... 

Methyl- and 2-ethyl-1,2,3,4-tetrahydroisoquinoline-l,3-dione were tricyanovinylated in position 4 to yield 412 (R = methyl, ethyl) or the 4-dicyanomethylene derivative 413 (R = methyl) ... 

The 5-dicyanomethylene derivative of spiro[cyclohexane-l,2 -(5 H)-3 /f-imidazo-[4,5-b]-pyridine]-5 -ylidene 649 was prepared from base 55 by treating with tetra-cyanoethylene at low temperature. In this case tetracyanoethylene acted both as an oxidizing agent and a reagent. 

Zemer et have used the ZINDO/SOS method in conjunction with AMI structural optimizations to investigate dicyanomethylene-derived heteroaromatic dyes. The effect of E/Z conformational isomerism and the introduction of various combinations of end groups on (the part of the tensor that is detected in EFISH experiments) is elucidated. Solvent effects are included through the self-consistent reaction field approximation. 

Otsubo et al. synthesized a series of soluble dicyanomethylene derivatives 2.88 ( = 1 -6) following a procedure similar to that reported for 2.87 (Chart 1.19). The absorption spectra of these compounds shifted from the visible to the NIR region. For example, derivative 2.88 (n = 6) showed a longest wavelength absorption at 1012 nm and a less intense absorption at 1371 nm due to the extended quinoidal stracture [173]. 

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