Aldolisation-type reaction versus Michael-type addition. Hemiacetal vinylogs: Versatile synthons.
作者:Pierre Duhamel、Jérôme Guillemont、Jean-Marie Poirier、Pierre Chabardes
DOI:10.1016/s0040-4039(00)60526-9
日期:1993.6
Depending on the steric hindrance of the reaction centers, hemiacetal vinylogs 1 in the presence of BF3.OEt2 can, with enol ethers, lead to a Michael-type addition (4) or an aldolisation-type reaction (3). Hemiacetal vinylog 1b always yields the second reaction leading to β-methoxy-γ,δ-ethylenic carbonyl compounds 4 precursors of polyenic carbonyl compounds 5. Crotonaldehyde and methanol can be used
取决于反应中心的空间位阻,在存在BF 3 .OEt 2的情况下,半缩醛乙烯基酯1与烯醇醚可导致迈克尔型加成反应(4)或醛缩反应型反应(3)。半缩醛乙烯基胶1b始终会产生第二个反应,从而生成多烯羰基化合物5的β-甲氧基-γ,δ-烯键羰基化合物4的前体。可以使用巴豆醛和甲醇代替化合物1b。