Hydrazine → HCID 178501787, compound

Participants

Reaction Steps

As depicted in Scheme 15, pyrazole-3-ol (15C) was prepared via the condensation of ketoester 15B with a hydrazine and then was alkylated to afford ether analogs. β-ketoester 15B was prepared by treating 1-(5-bromo-thiophen-2-yl)ethanone 15A with dimethyl carbonate in the presence of NaH. The resulting O-ketoester 15B and a hydrazine hydrochloride was heated to reflux in MeOH to give a mixture of 1H-pyrazole-3-ol 15C and the corresponding 3-methoxy-1H-pyrazole, which can be separated by chromatography. 15C reacted with methyl bromoacetate in the presence of K2CO3 in DMF to give [1H-pyrazol-3-yloxy]-acetic acid methyl ester 15D, which was treated with 3-methanesulfonylphenylboronic acid in the presence of Pd (PPh3)4 and aq Na2CO3 in THF to give Suzuki coupling product 15E. Ester 15E was hydrolyzed with aq NaOH in MeOH to afford acid 15F.

Provenance & Evidence