合成路线1

The hydrolysis of (1R,2R,3S,5S)-3-(benzoyloxy)-8-methyl-8-azabicyclo[3.2.1]octane-2-carboxylic acid methyl ester (I) with refluxing 1M HCl gives the corresponding hydroxy acid (II), which is dehydrated with refluxing POCl3 and treated with methanol to the unsaturated methyl ester (III). The reaction of (III) with 3,4-dichlorophenylmagnesium bromide in ether yields a mixture of (1R,2S,3S,5S)- and (1R,2R,3S,5S)-3-(3,4-dichlorophenyl)-8-methyl-8-azabicyclo[3.2.1]octane-2-carboxylic acid methyl esters (V) and (VI), respectively. Enantiomer (V) is isomerized to (VI) by treating the mixture with sodium methoxide in refluxing methanol. The reduction of (VI) with LiAlH4 in ethyl ether gives (1R,2R,3S,5S)-[3-(3,4-dichlorophenyl)-8-methyl-8-azabicyclo[3.2.1]octan-2-yl]methanol (VII), which is oxidized with oxalyl chloride in dichloromethane, affording aldehyde (VIII). Finally, this compound is treated with methoxyammonium chloride and Na2CO3 in methanol, giving brasofensine as an oil. Several salts of brasofensine were obtained by addition of the acid to a solution of brasofensine in ethanol and recrystallization from either water or isopropanol.