546C88 has been obtained by several related ways: 1) The reaction of N-methylthiourea (I) with methyl iodide gives N,S-dimethylisothiouronium iodide (II), which is then condensed with L-ornithine (III) by means of NaOH or copper acetate. 2) The oxidation of N-methylthiourea (I) with peracetic acid in acetic acid gives N-methylamidinosulfonic acid (IV), which is then condensed with L-ornithine (III) by means of K2CO3 in water. 3) The reaction of cyanogen bromide (V) with methylamine (VI) by means of Na2CO3 in THF gives N-methylcyanamide (VII), which is condensed with pyrazole (VIII) by means of HCl in refluxing dioxane to yield N1-methylpyrazole-1-carboxamidine (IX). Finally, this compound is condensed with L-ornithine (III) by means of LiOH in water. 4) The reaction of cellulose (X) with cyanogen bromide (V) by means of K2CO3 in water/DMF gives the corresponding polymeric cyanate ester (XI), which is condensed with methylamine (VI) to yield the polymeric N-methylamidino compound (XII). Finally, this compound is condensed with L-ornithine (III) by means of CuCO3 in water.
5) The reaction of L-ornithine (III) with benzaldehyde by means of LiOH gives Ndelta-benzylidene-L-ornitine (XIII), which is treated first with benzyl chloroformate and NaOH and hydrolyzed with HCl to afford Nalpha-(benzyloxycarbonyl)-L-ornithine (XIV). The condensation of (XIV) with N,S-dimethylisothiouronium iodide (II) by means of NaOH gives Nalpha-(benzyloxycarbonyl)-Nomega-methyl-L-arginine (XV), which is finally deprotected by hydrogenation with H2 over Pd/C.