Maleonitriles

Azidopyridazine 2-oxides give on thermolysis either maleonitrile (19), /3-cyanoacrylate (20) or 2-cyano-l-hydroxypyrazole (21), dependent on the substituent at the 6-position (Scheme 4) <75CC703>. 

Maleonitrile, l,2-dicyanoethylene-l,2-dithio-metal complexes, 6, 147 Malic acid metal complexes geochemistry, 6, 867 naturally occurring, 2,962 Malonic add... 

A number of other ligand groups are found to add to [Ni(CNBu )2] t, including azobenzene, tetracyanoethylene, fumaronitrile, and maleonitrile, diphenylacetylene and dimethyl acetylenedicarboxylate 109,110) [Eq. (29)]. 

Fig. 7.4 Structure of the [Mo3S7(C204)3]Br (a) and [Mo3S7(mnt)3]2 (b) adducts where the maleonitrile ligands on two molybdenum sites are omitted for clarity.

This procedure provides a convenient synthesis of aminomalononitrile, which has been demonstrated to be a useful intermediate for the preparation of substituted imidazoles, thiazoles, oxazoles, purines, and purine-related heterocycles.2 It is also a convenient starting material for the preparation of diamino-maleonitrile.2, 4... 

Porphyrazines (pz), or tetraazaporphyrins, are compounds that can be viewed as porphyrin variants in which the meso carbon atoms are replaced with nitrogen atoms, as Fig. 1 shows (1). This difference intrinsically gives porphyrazines discrete physiochemical properties from the porphyrins. In addition, despite their similar molecular architecture, porphyrazines are prepared by an entirely different synthetic route than porphyrins—by template cyclization of maleonitrile derivatives, as in Fig. 2, where the open circle with the A in it represents the peripheral substituent of the pz—rather than by the condensation of pyrrole and aldehyde derivatives (1). The pz synthetic route allows for the preparation of macrocycles with chemical and physical properties not readily accessible to porphyrins. In particular, procedures have been developed for the synthesis of porphyrazines with S, N, or O heteroatom peripheral functionalization of the macrocycle core (2-11). It is difficult to impossible to attach the equivalent heteroatoms to the periphery of porphyrins (12). In addition, the preparation and purification of porphyrazines that bear two different kinds of substituents is readily achievable through the directed cocyclization of two different dinitriles, Fig. 3 (4, 5, 13). 

The first stage in the preparation of the octapyridylporphyrazine is the synthesis of Mg[pzpy8] (40, Scheme 8) (20%) by the Mg-templated macrocyclization of bis(4-pyridyl)maleonitrile (39). Demetalation forms the octapyridylpz (41), which... 

Synthesis. These macrocycles are prepared from seven-membered ring dinitrile complexes, 84a-84c (Scheme 17), which contain either methylene, sulfur or oxygen in the five position (129). These cyclic dinitriles are synthesized by alkylating maleonitrile dithiolate or derivatives thereof with the corresponding dihalide. The dinitriles 84a-84c can be cyclized in magnesium propoxide to form porphyrazines 85a (33%), 85b (19%), and 85c (27%) (Scheme 17), which can be demetalated with trifluoroacetic to form 86a-86c. Additionally, 86a has been remetalated with nickel (87a, 92%), copper (88a, 95%), and zinc (89a, 94%). The sulfur and oxygen derivatives 85b, 85c, 86b, and 86c are of low solubility and are not suitable for further manipulation. 

Other unsymmetrical aminoporphyrazines have been prepared accordingly. The base-catalyzed cross-condensation of bis(dimethylamino)maleonitrile (99) with 1,2-dicyanobenzene (132) produced a statistical mixture of six possible products that represent hybrids between a heterosubstituted aminoporphyrazine and pc (9). The individual yields of all six products depend on the molar ratio of both starting dinitriles. For instance, a 25 1 ratio of dinitriles 99 and 132 produced mainly pz 133 (35%) along with 100 (Scheme 23). 

The mixed macrocyclization of the bifunctional benzenebis(l,3-diiminopyrroline) (138) with an excess of bis(dimethylamino)maleonitrile... 

The chloride ions of 143 are displaced by reaction with the dithiolene chelates, disodium maleonitrile dithiolate (Na2 mnt), benzene dithiolate (bdt)... 

Synthesis. Comacrocyclization of 2,5-diiminopyrrolidine (213) with 5 equiv of bis(dimethylamino)maleonitrile (99) produced 214. Subsequent demetalation with TFA gave 215 in 5% overall yield. Similarly, mixed macrocyclization of 2,5-diiminopyrrolidine 213 with 2,3-dipropyl-maleonitrile (33) produced pz 216 (3%). The yield of this reaction could be improved by conversion of dinitrile (33) into the diiminopyrroline derivative 212 using ammonia, to provide pz 216 in 17% yield. Demetalation of 216 furnished the free base 217 (91%). 

Vesey et al. 1976) and a series of commercially important, simple, aliphatic nitriles (e.g., acetonitrile, propionitrile, acrylonitrile, n-butyronitrile, maleonitrile, succinonitrile) (Willhite and Smith 1981) release cyanide upon metabolism. These drugs and industrial chemicals have been associated with human exposure to cyanide and have caused serious poisoning and, in some cases, death. 

Irradiation of the sodium salt 517 in a solution of maleonitrile in THF gave a 30% yield of the as-spiro[2.6]nonatrienedicarbonitrile 524 (Scheme 6.106). Analogously, fumaronitrile led to the trans-diastereomer 525 exclusively in 29% yield [193b], which was also obtained from (trimethylsilyl)tropylium tetrafluoroborate (519) as precursor of 5 [208]. The interception of 5 by dimethyl fumarate succeeded by generating 5 from 517 by either photolysis [193] or thermolysis [193, 194] and from 519 [208] and afforded the dimethyl trans-dicarboxylate 526 in yields of 50, 40 and 42%, respectively. Liberation of 5 in the presence of dimethyl maleate led also to 526 [194, 214], In this reaction, the isomerization of dimethyl maleate to fumarate could have interfered and hence pretended the loss of the stereochemical information, since... 

Abstract Bis(3-methylbutantio) maleonitril has been obtained from the reaction of disodium salt, l-bromo-3 methylbiitan in acetone under nitrogen for 11 hours. MgPz has been synthesized through the cyclotetramerization reaction of magnesium and n-butanol with bis(3-methylbutantio) maleonitril. The metal free pophyrazine derivative was obtained by its treatment with trifluroacetic acid and further reaction of this product with cobalt(II) acetate, nickel(II) acetate and zinc(II) acetate led to the metal porphyrazine (MPz, M = Co, Ni ve Zn). These new compounds have been investigated and characterized by UV, FT-IR, H NMR, GC-MS and elemental analysis methods. 

For the synthesis of MgPz (2), the alkylated maleonitrile was treated with Mg butanolate. Because of the template effect of magnesium, maleonitrile molecules cyclotetramerize to form magnesium porphyrazine. MgPz is soluble in number of common solvents like chloroform, acetone etc. and little soluble in ethanol and methanol. The absence of CN peaks in IR spectram can easily be attributed to the cyclotetramerization, and the only strong peak was observed at 2,922 cm for C-H stretching vibration of 3-metylbutane groups. 

Abstract Magnesium porphyrazines substituted with eight (phenyl-propene) groups on the peripheral positions have been prepared by cyclotetramerization of l,2-bis(3-phenyl-2-propenethio) maleonitrile and then achieved porphyrazine by 3-bromo-l-phenyl-l-propene. Metal-free derivative was obtained by its treatment with trifluoroacetic acid. The new compounds have been characterized by FT-IR, H-NMR, UV-VIS and elemental analysis methods. 

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