Sodium borohydride → Tert-butyl 4,6-dihydroxyspiro[chromane-2,4'-piperidine]-1'-carboxylate

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Reaction Steps

A solution of the product from step 1 (4.51 g, 13.5 mmol) in methanol (50 mL) was cooled to 15° C. and sodium borohydride was added slowly and the mixture was further stirred for 30 min and then concentrated. The crude residue was partitioned between methylene chloride and water and the aqueous layer was extracted twice with methylene chloride. The combined organics was washed with brine, dried (Na2SO4), filtered and concentrated to produce the product of step 2 (4.1 g, 90%), mp 171-173° C. (ethyl acetate, ether and hexane), MS m/z=334 (M−H).

Provenance & Evidence