Hydrochloric Acid → (R)-2-(1H-indol-5-yl)-4,5-dihydrothiazole-4-carboxylic acid

Participants

Reaction Steps

(R)-2-(1H-indol-5-yl)-4,5-dihydrothiazole-4-carboxylic acid 63a was synthesized using the same method as used for 42a from 1H-indole-5-carbonitrile and used without further purification. To a vigorously stirring solution of 63a (1 mmol) and tetrabutylammonium hydrogen sulfate (0.15 mmol) in toluene (10 mL) at 0° C. was added 50% aqueous sodium hydroxide (10 mL) and sulfonyl chloride (2 mmol). The resultant solution was stirred at RT for 6 h. Then 1 N HCl was added to acidify the mixture to pH=2 and extracted with CH2Cl2, the organic layer was separated and dried (MgSO4); then evaporated to dryness to yield 64a, which were used in subsequent steps without further purification.

Provenance & Evidence