Ammonium Acetate → 3-Amino-5-phenylthiopyran

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Reaction Steps

This compound was prepared as shown in Scheme 25. Thus, to 0.96 g (5 mmol) of 5-phenyl-3-thiopyranone (P. T. Lansbury, et al., J. Am. Chem. Soc. 1970, 92, 5649) in 50 mL of anhydrous methanol was added 7.7 g (100 mmol) of ammonium acetate and 6.5 g of 3A molecular sieves. After stirring 30 minutes at room temperature, 1.25 g (20 mmol) of sodium cyanoborohydride was added portionwise. After stirring 16 hours, the mixture was gravity filtered, and the methanol was evaporated under vacuum. The residue was partitioned between ice/HCl and ether. The acidic aqueous phase was extracted twice more with ether, then it was made basic with ice and 50% NaOH aqueous. The mixture was extracted with CH2Cl2, dried (MgSO4), and evaporated to give 0.19 g (20%) of the title compound. GC/MS showed 100% purity with a molecular ion of 193.

Provenance & Evidence