Thiourea → Benzoylurea

In Scheme 3, step L, substep 1, the fluorinated primary alcohol (prepared in Scheme 1, step H) is deprotected under standard conditions followed by neutralization, thiourea formation and cyclization in substeps 2a and 2b to provide the protected bicyclic aminooxazine. For example, in substep 1, the fluorinated primary alcohol is dissolved in a suitable organic solvent, such as ethyl acetate or dichloromethane and treated with an excess of a suitable acid such as hydrochloric acid (4 M in 1,4-dioxane) or trifluoroacetic acid. The reaction is stirred at room temperature for about 2 hours to overnight. The deprotected amine is then isolated with techniques well known in the art such as filtration as a salt. Alternatively for substep 1, ethanol is added drop wise to a solution of excess acetyl chloride in ethyl acetate at about 0° C. and stirring for about 30 minutes. The fluorinated primary alcohol, (Scheme 1, step H) is added and the reaction is stirred overnight at room temperature. The deprotected amine salt is then isolated with techniques well known in the art such as filtration. Then, for the neutralization and thiourea formation for substep 2a, the deprotected amine salt is dissolved in a suitable organic solvent, such as acetonitrile or tetrahydrofuran and treated with about 1.1 equivalents of a suitable organic amine, such as triethylamine to neutralize the amine, and about 1.05 equivalents of benzoyl isothiocyanate is added to form the intermediate thiourea. The reaction is then stirred at 5° C. for about 1 hour or heated to about 70° for 2 hours. To cyclize and form the protected bicyclic aminooxazine in substep 2b, about 1.1 equivalents of trimethylsilyl chloride and DMSO are added and stirring is continued for about 2 hours. The reaction is quenched with potassium phosphate dibasic (20%) to adjust the pH to 7-8 and the product is isolated using techniques well known in the art to give the protected bicyclic aminooxazine product of step L. Alternatively, the amine salt can be neutralized with triethylamine as described above for step L, step 2a, and treated with benzoylcarbamate to form an N-carbamoyl benzamide intermediated that is then cyclized with diethylaminosulfur trifluoride in an organic solvent such as dichloromethane at about −78° C. and warmed to about room temperature over 1 hour. The product is isolated using techniques well known in the art to give the protected bicyclic aminooxazine product of step L.