DIASTEREOSELECTIVE SYNTHESIS OF HIGHLY SUBSTITUTED 2,5-DIAMINOHEXANESVIA NITRILE OXIDE CYCLOADDITION TO A VINYLOGOUS AMINO-ACID

A novel route to 1,6-disubstituted 2,5-diamino-3-hydroxy-4-hydroxymeth ylhexanes is described. N-protected ethyl (2E,4S)-4-amino-5-phenylpent -2-enoate undergoes cycloaddition with nitrile oxides producing the sy n and anti isomers of ethyl isoxazoline-4-carboxylates in a 2 : 1 rati o. The individual isomers are converted into 1,4-diaminohexanes via ch emoselective ester reduction with lithium aluminum hydride, followed b y highly diastereoselective reductive cleavage of the isoxazoline ring with borane-dimethylsulfide complex.