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Lead-Mediated Highly Diastereoselective Allylation of Aldehydes with Cyclic Allylic Halides
- Cheng, Bu-Qing, Zhao, Shi-Wen, Song, Xuan-Di, Chu, Xue-Qiang, Rao, Weidong, Loh, Teck-Peng, Shen, Zhi-Liang
- Journal of organic chemistry 2019 v.84 no.9 pp. 5348-5356
- alcohols, aldehydes, allylation, carbonyl compounds, diastereoselectivity, lithium chloride, moieties, organic chemistry, organobromine compounds
- Lead was found to efficiently mediate the allylation reactions of carbonyl compounds with cyclic allylic halides in the presence of stoichiometric amounts of lithium chloride and a catalytic amount of GaCl₃ (20 mol %), leading to the desired homoallylic alcohols in modest to high yields with excellent diastereocontrol (>99:1 syn/anti) and good functional group tolerance. In contrast, the use of either 2-pyridinecarboxaldehyde as the carbonyl substrate or (E)-cinnamyl bromide as the allylating agent produced the corresponding product with reversed diastereoselectivity (>99:1 anti/syn).