Synthesis of some optically active terpenoid-derived thioamides

<p>Several terpenoid-derived thioamides have been synthesized in the reactions taking advantage of the electrophilicity of the carbonyl function in terpenones and the nucleophilicity of the terpenone lithium enolates. The optically active β-hydroxythioamide derivatives <b>4, 6, 8, 10, 12</b> have been obtained by reacting the thioacetanilide dianion <b>2</b> with terpenones. The reaction of the enolate anions of (-)-menthone and (1R)-(+)-camphor with phenyl isothiocyanate gave rise to the formation of the corresponding β-ketothioamides <b>13</b>, <b>14</b>. In a multicomponent reaction (MCRs) with benzylamine and formaldehyde, <b>14</b> yielded the spirohexahydropyrimidine <b>15</b>.</p