Oxazoles, 5-methylene-4,5-dihydro

Oxazole, 2,5-dihydro-4-methoxy-synthesis, 6, 228 Oxazole, dihydro-2-methylene-reactions, 6, 215... 

A new heterocyclic system, 3 ,4-dihydro-3//-benzo[4,5]imidazo[l,2-f]oxazol-l-one 462, was synthesized by reaction of 4,4-dimethyl-5-methylene-l,3-dioxolan-2-one with o-phenylenediamine in the presence of copper bromide as catalyst in carbone dioxide at 60-80 °C under high pressure (Equation 217) <1999CHC216>. 

Furan 2-Aminomethyl-5-(2,4-dioxo-1,2,3,4-tetrahydro-pyrimidino)-2,5-dihydro- IV/lc, 578 Imidazo(l,2-a]pyridin 1,5-Dimethyl-8-nitro-7-oxo-l,2,3,7-tetrahydro-E15/3, 2790 [cycl. (R2N)2C = CH-N02 4- Diketen] 1,3-Oxazol 4-Cyan-5-(diethoxy-methylen-amino)- E4, 565 (Het — NH2 + Orthoester) Pyrazin 3-Amino-2-methoxycarbo-nyl-5-propanoyl- E9b/2, 324 (H - CO-R)... 

Benzoxazol 2-(Cyan-formyl-methylen)-2,3-dihydro- E15/2, 1812 [aus 2-(l,2-Oxazol-4-yl)-1,3-benzoxazol]... 

FIGURE 10.1 Pharmacophore model representation derived from the cycUn-dependent kinase 2 (CDK2) inhibitor 3- [(2,2-Dioxido-l,3-dihydro-2-benzothien-5-yl)amino]-methylene -5-(l,3-oxazol-5-yl)-l,3"dihydro-2H-indol-2-one in its binding site, PDB entry Ike processed using LigandScout ... 

Synthesen von 4-Methylen-5-oxo-4,5-dihydro-l, 3-oxazolen werden haufigalsEin-topf-Reaktion durchgefiihrt, wobei im ersten Reaktionsschritt das 5-Oxo-4,5-dihydro-l,3-oxazol gebildet wird und anschlieBend die Kondensation mit dem Aldehyd erfolgt72,73. 

Flash vacuum pyrolysis of 4-methylene-5-oxo-4,5-dihydro-l,2-oxazoles (93) at 700—800 C gives terminal acetylenes in good yield, provided that (93) is volatile and stable at this temperature. Thus a range of heteroaromatic aldehydes can be converted into the corresponding homologous acetylenes by this route. 

A methanolic soln. of 4-[(chromon-3-yl)methylene]-5-oxo-2-phenyl-4,5-dihydro-l,3-oxazole refluxed 45 min. in the presence of anhydrous Na-carbonate 2-meth-oxycarbonyl-4-(2-hydroxybenzoyl)pyrrole. Y 74%. F. e., also thiophene analogs, s. A. O. Fitton et al.. Synthesis 1977, 133. 

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