Hydrochloric Acid → Spiro[cyclobutane-1,3'-indolin]-2'-one

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Reaction Conditions

Reaction Steps

Under a nitrogen atmosphere 1.50 g (7.89 mmol) cyclobutanecarboxylic acid N-phenylhydrazide and 530 mg (12.6 mmol) calcium hydride were mixed thoroughly and heated to 230° C. The mixture was stirred for 30 min at 230° C. and then cooled to RT again. The reaction mixture was carefully mixed with a solution of 7 mL water and 16 mL methanol. It was stirred for 1 h until no more hydrogen was released. Then the pH was adjusted to 1 with concentrated hydrochloric acid solution and the mixture was stirred for 1 h at 100° C. Using 4M sodium hydroxide solution the pH was adjusted to 3 and stirred overnight at RT. The precipitated substance was suction filtered and washed with 10 mL water. The mother liquor was evaporated down i.vac. and the residue was purified by preparative HPLC. The product fractions were combined, evaporated down i.vac. and dried.

Provenance & Evidence