Scandium triflate catalyzes the addition of camphor-derived allyl-, methallyl-, and crotylboronates to aldehydes to provide homoallylic alcohols with excellent diastereo- and enantioselectivity. Aromatic, aliphatic, and propargylic aldehydes can be used successfully in this system. Additional advantages of the camphor-diol allylboronates are their ease of synthesis, their availability in both enantiomeric forms, and their stability towards silica gel chromatography. The usefulness of this methodology is further demonstrated by the gram-scale synthesis of various homoallylic alcohols of high enantiomeric excess and by the concise synthesis of the pheromone (4S)-2-methyloctan-4-ol.
三氟甲磺酸钪催化从
樟脑衍生的烯丙基、异烯丙基和克罗丁基
硼酸酯与醛的加成反应,生成具有优异的反式选择性和对映体选择性的同
烯丙醇。芳香族、脂肪族和炔基醛在该体系中均可成功使用。
樟脑二醇烯丙基
硼酸酯的其他优点包括合成方便、可获得两种对映体形式以及对
硅胶柱层析的稳定性。该方法的实用性进一步体现在高对映体过量的各种同
烯丙醇的克级合成以及信息素(4S)-2-甲基
辛醇的简洁合成中。