4- Aminomethylene

Shaw concluded that hydrogenation of 3-alkyl-4-aminomethylene isoxazol-5-ones (184) in the presence of palladium catalyst resulted in the saturation of either the endocyclic double carbon-nitrogen bond or the exocyclic double C—C bond with the retention of the heterocyclic nitrogen-oxygen bond. Recent data reported by Kochetkov et al. on the properties, and in particular on hydrogenation, of isoxazolid-5-ones - indicate, however, that Shaw had probably ob-... 

The protecting reaction of the enamino pyrrolidinone with t-butoxycarbonyl anhydride was carried out by mixing 4-(N-/-butoxycarbonyl)-4-aminomethylene-pyirolidin-3-one (Boc-AMP) with 1.2 molar equivalents of t-butoxycarbonyl anhydride (/-BoczO) to make l-(N-f-butoxycarbonyl)-4-(N-t-butoxycarbonyl)-ammomethylene-pyrrolidin-3-one (B0C2-AMP). Several types of reactors, including batch reactors, a continuous stirred tank reactor (CSTR),... 

Condensation of an Al -heteroaryl-7/,7/-dimethylformamidine or 7/,Al -diphenyl-formamidine with 2-phenyl-5(47/)-oxazolone 146 gives 4-(aminomethylene)-2-phenyl-5(47/)-oxazolones 207 that are synthetic equivalents of p-amino-a,p-dehy-dro-a-amino acid derivatives 208 (Scheme 7.63). ... 

Isocyanides have also been used to prepare unsaturated 5(4//)-oxazolones and they are particularly useful for the synthesis of 4-(aminomethylene)-5(4//)-oxazo-lones 374. For instance, cyclization of an unsaturated isocyanide obtained from condensation of alkyl isocyanoacetates and lactam acetals has been reported (Scheme 7.120). ° ... 

TABLE 7.37. SYNTHESIS OF 4-(AMINOMETHYLENE)-5(477)-OXAZOLONES FROM 4-HETEROMETHYLENE-5(477)-OXAZOLONES... 

Aminomethylene)-2-phenyl-5(47/)-oxazolone 418 has been converted to 4-(alkylthiomethylene)-2-phenyl-5(47/)-oxazolones 419 by treatment with carbon disulfide and subsequent alkylation. These 4-(alkylthiomethylene) analogues are useful intermediates for biologically active peptides, pharmaceuticals, and plant-protective agents (Scheme 7.136 Table 7.38, Fig. 

Transamination reactions have also been described for 4-(aminomethylene)-2-substituted-5(47T)-oxazolones. As an example, displacement of the A-methyl-heteroarylamino group of a 4-[(A-heteroaryl-A-methyl)aminomethylene]-2-phen-yl-5(47T)-oxazolone 420 by an a-amino acid derivative produces p-amino-a,(3-dehydro-a-amino acid precursors 421 (Scheme 7.137). ... 

Enamine exchange with the weakly basic amino group of 4-(aminomethylene)-2-phenyl-5(477)-oxazolone 418 leads to the 4-[(A-cycloalkenyl)aminomethylene]-5(47/)-oxazolones 422, that thermally cyclize to afford [h]-fused bicyclic 4-pyridones 423 (Scheme 7.138). ... 

Reaction of 4-arylidene-2-phenyl-5(4//)-oxazolones 593 with A-phenacylpyri-dinium bromide proceeds by the same sequence to give oxazolo[5,4-/>]pyridines 594 (Scheme 7.188) while the reaction of 4-(aminomethylene)-2-phenyl-5(4//)-oxazolone 418 and phenyl isothiocyanate gives pyrimidin-2-thiones 595 (Scheme 7.189). In this latter case initial attack of the exocylic amino group produces an intermediate thiourea (not shown) that subsequently cyclizes to 595. 

Ethoxymethylene)-5(477)-oxazolones are useful intermediates to prepare a variety of other 4-heteromethylene-5(47/)-oxazolones. In this context, 4-(ethoxy-methylene)-5(4//)-oxazolones 809 were converted to 4-(aminomethylene)-5(4//)-oxazolones 810 by reaction with amines as shown in Scheme 7.248. ° ... 

TABLE 7.38 SYNTHESIS OF 4-(ALKYLTHIOMETHYLENE)-5(4//)-OXAZOLONES FROM 4-(AMINOMETHYLENE)-5(4//)-OXAZOLONES, 224... 

Synthesis of Metal Chelates of 4-Aminomethylenic Derivatives of 5-Thio(seleno)pyrazoles (2.13), (3.57) [68,73a]... 

Complexes were prepared by refluxing (5-10 min) equimolecular quantities of nickel acetate with the respective 4-aminomethylene derivatives of 1,3-substituted 5-thio(seleno)-N-pyrazoles in ethanol solution. All the complexes thus obtained were purified by repeated crystallization... 

The ICC, synthesized on the basis of 4-aminomethylene derivatives of 5-imine-, oxo-, thio-, and selenoderivatives of pyrazole, are represented most widely. The coordination units MN4, MN202, MN2S2, and MN2Se2, respectively, are found in them [100,134,176-186], Thus, the methods A and B (4.49) were used for obtaining ICC of type 868 (X = NR, R-Het, compound 222) [187] ... 

Coned. NH4OH added to a stirred mixture of 3-bromoacetyl-4H-l-benzopyran-4-one and methanol, and the product isolated after a few min. -> 4-aminomethylene-l-benzoxepin-3,5(2H,4H)-dione. Y 73%. F. rearrangement reactions s. Klutchko and M. v. Strandtmann, Synthesis 7977, 61. 

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