[Cl:1][C:2]1[C:3]2[C:10]([C:11]([OH:13])=O)=[CH:9][NH:8][C:4]=2[N:5]=[CH:6][N:7]=1.C[N:15](C=O)C.C(Cl)(=O)C(Cl)=O>C(Cl)Cl.C1COCC1>[Cl:1][C:2]1[C:3]2[C:10]([C:11]([NH2:15])=[O:13])=[CH:9][NH:8][C:4]=2[N:5]=[CH:6][N:7]=1To a stirred suspension of 4-chloro-7H-pyrrolo[2,3-d]pyrimidine-5-carboxylic acid (G-1) (3.11 g, 15.7 mmol, 1.0 eq) and a catalytic amount of DMF in a mixture of DCM (40 mL) and THF (40 mL) at RT, oxalyl dichloride (2.0 mL, 23.5 mmol, 1.5 eq) is added dropwise. The resulting mixture is stirred for 2 h and then concentrated in vacuo. The residue (G2) is dissolved in DCM (50 mL) and the resulting solution is added dropwise to saturated aqueous ammonium hydroxide (200 mL) at RT. The resulting mixture is stirred for 30 min and then filtered. The filter cake is then rinsed with H2O (30 mL×2). The filtrate is acidified with con. HCl to adjust the pH to 4-5. The solid is collected by filtration, rinsed with water and dried in vacuo to afford the product, 4-chloro-7H-pyrrolo[2,3-d]pyrimidine-5-carboxamide (G-3).
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