| 摘要 |
<p>The cpds. of formula where R' is Me, Et, CH3S.CH2- or CH3O.CH2-, R2 is Me, Et or Pr, and R3 is H or Me, are prepared by reaction of a thiolhydroxamate ester (I) of formula with isocyanic acid (II) or its Me ester (III). Reaction is carried out in a medium consisting of 50% water and is not >50% of a miscible org. solvent, at temp. between 0 and the b.p. of the reaction mixture (pref. 0-25 using (II) and 20-60 using III), the initial conc. of (I) being 5-50% (pref. 10-30%) based on total wt. of reaction mixture. (II or III) is pref. 1.0:1 to 1.2:1). (II) is pref. generated in situ. by addition of an alkali metal cyanate and a mineral acid to (I).</p> |
