Highly efficient synthesis of allylic alcohols having an α-alkoxyalkyl group at their β-position via regioselective addition reaction of titanium-propargyl ether complexes with carbonyl compounds
作者:Koki Yamashita、Fumie Sato
DOI:10.1016/0040-4039(96)01647-4
日期:1996.9
Diisopropoxytitanium-propargyl ether complexes 2, readily generated in situ from reagent and propargylic ethers 3, react with aldehydes and ketones highly regioselectively at the carbon having an α-alkoxyalkyl group, thus affording an efficient and practical method for synthesizing allylicalcohols 4 having an α-alkoxyalkyl group at the β-position. The synthesis of conjugated dienes 7h and 8h from
Preparation of polyfunctional allenic alcohols by the regioselective addition of functionalized propargylic chromium(III) organometallics to carbonyl compounds
作者:Kevin Belyk、Michael J. Rozema、Paul Knochel
DOI:10.1021/jo00041a006
日期:1992.7
The reaction of propargylic halides 1 (X = Cl, Br) with an aldehyde or ketone (0.67 equiv) in the presence of CrCl2 (2.0 equiv) and LiI (2 equiv, necessary if X = Cl) affords allenic alcohols 3 with excellent regioselectivities (3-6% of the regioisomeric acetylenic alcohol 4 is formed) and in good yields (68-90%). Interestingly, this method allows the generation of highly functionalized intermediate propargylic chromium organometallics contained an ester, cyano, or chloride functionality. The alpha-alkyl-substituted propargylic bromide 10 reacts with benzaldehyde yielding the acetylenic alcohol 11 as a diastereomeric mixture of only one regioisomer (90% yield).