To a stirred or shaken solution of 157 mg (0.76 mmol) of (4S,5S)-2,2-dimethyl-4-phenyl-1,3-dioxan-5-amine (abbreviated as (4S,5S)-amine 1) in pentane (3.5 mL) was added dropwise a solution of 169 mg (0.73 mmol) of 4-bromo-2-chlorophenyl isocyanate in dichloromethane (0.7 mL). A white precipitate was observed after stirring for 0.5 to 2 h. The precipitate was collected, rinsed with pentane, and dried under vacuum to yield 280 mg (88%) of the title compound. In some examples, pentane was used to dissolve the required isocyanate rather than dichloromethane. In addition, if the required isocyanate was a liquid, it was added dropwise as a neat liquid on small-scale reactions such as this. In cases where a precipitate was not observed or the precipitate was not of sufficient purity, the solvent was evaporated, and the residue was purified by column chromatography (hexanes/ethyl acetate) to yield the desired product.
