The starting material L-rhamnose was converted into 2,3,4-tri-O-acetyl-β-L-rhamnopyranosyl bromide in good yield by treating with ace-tic anhydride and then Br₂. The key intermediate 2,3,4-tri-O- ace-tyl-α-L-rhamnopyranosyl isothiocyanate was obtained by reaction of triace-tyl-β-L-rhamnosyl bromide with Pb(SCN)₂ in boiling toluene. The nucleophilic addition of rhamnosyl isothiocyanate to substituted 2-aminobenzothiazoles (2a～2f), 2-hydrazinobenzothiazoles (2g～2l), oxidized and nonoxidized 3-hydra- zinocar-bonyl-pyridazin-6-ones (2m, 2n) and 2-aminopyrimidines(2o, 2p) in dif-ferent solvent system afforded a series of rhamnosyl thioureas and thiosemicarbazides respectively. The structures of all 16 new compounds 3a～3p have been confirmed by IR, ¹H NMR, LC-MS spectra and elemental analysis. Biological activity has been elementarily evaluated.

Key words: rhamnosyl isothiocyanate, pyrimidine, (amino)thiourea, 3-hydrazinocarbonyl-pyridazin-6-one, benzothiazole