(E)-4-oxopent-2-enoic acid

Conditions: temp:0.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: (2E)-4-Oxopent-2-enoic acid (7.06 g, 60 mmol) and Et3N (8.7 ml, 63 mmol) are dissolved in CH2Cl2 (150 ml). The solution is cooled to 0° C. Then iBuOCOCl (8.8 ml, 67 mmol) in CH2Cl2 (10 ml) is added dropwise at ≦4° C. over 10 min. The resulting suspension is stirred for 25 min at 0° C. Et2NH (7.5 ml, 72 mmol) in CH2Cl2 (5 ml) is added dropwise over 10 min at ≦4° C. After 1.5 hours strung at 0° C., additional Et2NH (73.8 ml, 36 mmol) is added and stirring is continued for 3 hours. Then the reaction mixture is poured into 2 M HCl (100 ml) and extracted with TBME (750 ml and 2×250 ml). The organic phases are washed with 2 M HCl (100 ml), saturated NaHCO3 (100 and 50 ml) and brine (2×50 ml) successively. The combined organic phases are dried with Na2SO4 and evaporated under reduced pressure at 40° C. The residue is purified by flash chromatography (AcOEt:heptane fraction 50:50 to 60:40) and yields 26 (diethyl (2E)-4-oxopent-2-enamide) (7.16 g, 71%) as a pale orange oil. After 1.5 hours strung at 0° C. stirring is continued for 3 hours extracted with TBME (750 ml and 2×250 ml) The organic phases are washed with 2 M HCl (100 ml), saturated NaHCO3 (100 and 50 ml) and brine (2×50 ml) successively The combined organic phases are dried with Na2SO4 evaporated under reduced pressure at 40° C The residue is purified by flash chromatography (AcOEt:heptane fraction 50:50 to 60:40)

Conditions: temp:0.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: (2E)-4-Oxopent-2-enoic acid (9.41 g, 80 mmol) and EtNH2 (2 M in THF, 40 ml, 80 mmol) are dissolved in CH2Cl2 (250 ml). The solution is cooled to 0° C. Then DMAP (1.47 g, 12 mmol) and EDCl (15.34 g, 80 mmol) are added. The resulting suspension is stirred for 17 h at 0 (C. Then the reaction mixture is poured into 2 M HCl (100 ml) and extracted with CH2Cl2 (2×1 l). The organic phases are washed with 2 M HCl (50 ml), saturated NaHCO3 (50 ml) and brine (100 ml) successively. The combined organic phases are dried with Na2SO4 and evaporated under reduced pressure at 40° C. 24 (ethyl (2E)-4-oxopent-2-enamide) (5.74 g, 51%) is obtained as a brown solid. extracted with CH2Cl2 (2×1 l) The organic phases are washed with 2 M HCl (50 ml), saturated NaHCO3 (50 ml) and brine (100 ml) successively The combined organic phases are dried with Na2SO4 evaporated under reduced pressure at 40° C