Conjugate addition of thiophenol to γ-alkoxy-alkynone, 4, proceeds with up to 4:1 Z:E stereoselectivity. However, 2-mercaptobenzothiazole reacts to afford only the Z-isomeric vinyl sulfides. The Z-vinyl sulfides are readily converted to stereopure E-β-disubstituted enone, 8a, providing a convenient, practicable 2-step synthesis. 8a and 8b are also obtained via cuprate addition-equilibration, but with a Z:E
在γ-烷氧基-炔基酮4上共轭添加
苯硫酚时,Z:E立体选择性高达4:1 。然而,
2-巯基苯并噻唑反应仅得到Z-异构体
乙烯基硫化物。所述ž -
乙烯基硫化物容易地转化为stereopure Ë -β二取代的烯酮,8a中,提供了方便,可行的2步合成。图8a和图8b还获得通过
铜酸盐加成平衡,但具有ž:é的≤1比:3.8。