合成路线1

The hydroboration of allyl bromide (I) with diisopinocampheylborane gives the 3-bromopropylboronic ester (II), which by treatment with acetaldehyde and water yields the boronic acid (III). The reaction of (III) with NaN3 and ethanol affords 3-azidoboronic acid ethyl ester (IV), which is transesterified with optically active pipanediol (V) giving the cyclic ester (VI). The homologation of (VI) with LDA, ZnCl2 and dichloromethane in THF yields the alpha-chlorobutylboronic ester (VII), which is aminated with hexamethyldisylazane (HMDS) and BuLi to provide the silylated alpha-aminoboronic ester (VIII). The desilylation of (VIII) with methanol, and its protection with benzyl chloroformate gives the protected alpha-aminoboronic ester (IX). The hydrogenation of the azido group of (IX) with H2 over PtO2 affords the 4-aminobutylboronic ester (X), which is treated with N,N'-bis(tert-butoxycarbonyl)thiourea (XI), HgCl2 and TEA in DMF to give the guanidine derivative (XII). Finally, this compound is hydrolyzed and deprotected with refluxing 6N HCl.