2,3-Dihydropyrano[2,3-b]pyridin-4(4H)-one synthesis

Yield:286472-03-5 27%

Reaction Conditions:

with sodium acetate;acetic anhydride at 160; for 2 h;Heating / reflux;

Steps:

21.1

Example 21 Preparation of (5R, 6Z)-7-oxo-6- (4H-thieno [2', 3' : 4, 51thiopyranor2, 3-blpvridin-2- ylmethylene)-4-thia-1-azabicyclo [3. 2. Olhept-2-ene-2-carboxylic acid (Sodium salt) Step 1: 2, 3 dihvdro-4H-thiopyranor2, 3-blpyridin-4-one : A solution of 14 g. (61.6 mmol) 3- (3-Carboxy-2-pyridylthio) propionic Acid [prepared as described in lit. : J. Heterocyclic Chem.. 37. 379 (2000)] and 15 g. (185 mmol, 3 eqs) of anhydrous sodium acetate, in 200 mL. of acetic anhydride was refluxed (160° C) under stirring, N2 atm, dry conditions, for 2 hours. Cooled, diluted with 300 mL of water, basified with 30% ammonium hydroxide solution to pH 8-9, extracted with 3x200 mL chloroform. Combined organics washed with 2x60 mL Sodium bicarbonate (satn. sol), water, dried, evaporated, gave 2.8g. (27%) of the title compound, reddish solid, m. p. 66-8° C, (M+H) +=166. 2.

References:

WO2003/93280,2003,A1 Location in patent:Page/Page column 136