合成路线1

Synthesis of the 3-pyrroline intermediate (XXVI): The reaction of 4-hydroxy-2-methylenebutyric acid methyl ester (XIV) with Tbdps-Cl and imidazole in DMF gives the silyl ether (XV), which is reduced with DIBAL in dichloromethane to yield the butanol derivative (XVI). The reaction of (XVI) with MsCl and TEA affords the corresponding mesylate (XVII), which is condensed with allylamine (XVIII) to provide the secondary amine (XIX). The protection of the NH group of (XIX) by reaction with Boc2O and TEA gives the carbamate (XX), which is submitted to a ring closing metathesis reaction using a Grubbs Ru catalyst to yield the 3-pyrroline derivative (XXI). The cleavage of the silyl ether group of (XXI) by means of TBAF in THF affords the pyrroline ethanol derivative (XXII), which is treated with PPh3, DEAD and (PhO)2P(O)N3 in THF to provide the azido derivative (XXIII). The deprotection of the NH group of (XXIII) by means of TFA in dichloromethane gives the 3-(2-azidoethyl)-3-pyrroline (XXIV), which is treated with Goodman's reagent to yield the protected amidino derivative (XXV). Finally, the azido group of (XXV) is reduced by means of PPh3, water and AcOH to afford the desired 3-pyrroline-1-carboxamidine (XXVI).