Synthesis of Geminally Activated 4-(Furan-2-yl)- and 4-(Thiophen-2-yl)-1-nitrobuta-1,3-dienes

Primary nitro compounds: progress in the synthesis of isoxazoles by condensation with aldehydes or activated ketones

“…Other nitroenones 18 are reported under different experimental conditions: Al 2 O 3 in CH 2 Cl 2 at room temperature, 57 thionyl chloride in ethanol at rt or heating 58,59 and β-alanine and acetic acid in benzene under reflux; 60–65 phosphoryl chloride in ethanol at room temperature; 66 acetic anhydride at 120–130 °C, 67 (2 S )-2-{diphenyl[(trimethylsilyl)oxy]methyl}pyrrolidine and 4-nitro-benzoic acid in dichloromethane; 68 and 4-methyl-morpholine and titanium tetrachloride at 0 °C. 69…”

“…Nitroenones 18 have been prepared from the Schiff bases of aromatic aldehydes with n-butylamine; the addition product with nitroacetone ( 16), in acetic anhydride, affords 18 (Scheme 10, R = aryl, 5 examples, including 2-furyl). 56 Other nitroenones 18 are reported under different experimental conditions: Al 2 O 3 in CH 2 Cl 2 at room temperature, 57 thionyl chloride in ethanol at rt or heating 58,59 and β-alanine and acetic acid in benzene under reflux; [60][61][62][63][64][65] phosphoryl chloride in ethanol at room temperature; 66 acetic anhydride at 120-130 °C, 67 (2S)-2-{diphenyl[(trimethylsilyl)oxy]methyl}pyrrolidine and 4-nitro-benzoic acid in dichloromethane; 68 and 4-methyl-morpholine and titanium tetrachloride at 0 °C. 69 They can be isolated as they do not undergo Michael addition with nitro ketones under the reported conditions.…”

Nitroacetonitrile and Its Synthetic Equivalents

“…This protocol is useful for generating a library of compounds by simply altering aldehydes 7 , which facilitates biological activity evaluation. − The synthesis of push–pull alkenes (Ar = electron rich aryl), applicable in the development of nonlinear optical materials, is readily achieved upon treatment of NAN with electron-rich aldehydes. , When α,β-unsaturated aldehydes 9 (Ar = substituted phenyl, heteroaryl) are used, nucleophilic attack of NAN (1,2-addition) occurs at the formyl group to afford butadienes 10 in moderate yields (Scheme ). , Thioamides are also applicable as substrates in place of aldehydes 7 for condensation with NAN . Several green processes have been developed, such as conducting the condensation of NAN with aldehydes 7 in aqueous media , and using the recyclable natural catalyst, dolomite [CaMg­(CO 3 ) 2 ], in water …”

“…32,33 When α,β-unsaturated aldehydes 9 (Ar = substituted phenyl, heteroaryl) are used, nucleophilic attack of NAN (1,2-addition) occurs at the formyl group to afford butadienes 10 in moderate yields (Scheme 4). 34,35 Thioamides are also applicable as substrates in place of aldehydes 7 for condensation with NAN. 36 Several green processes have been developed, such as conducting the condensation of NAN with aldehydes 7 in aqueous media 37,38 and using the recyclable natural catalyst, dolomite [CaMg(CO 3 ) 2 ], in water.…”