Metal-Mediated Retro-Allylation of Homoallyl Alcohols for Highly Selective Organic Synthesis

被引:74
作者
Yorimitsu, Hideki [1 ]
Oshima, Koichiro [1 ]
机构
[1] Kyoto Univ, Dept Chem Mat, Grad Sch Engn, Nishikyo Ku, Kyoto 6158510, Japan
关键词
CARBON-CARBON BOND; PALLADIUM-CATALYZED ARYLATION; ALLYLIC ZINC REAGENTS; C-C BOND; ARYL HALIDES; LITHIUM PENTAMETHYLCYCLOPENTADIENIDE; NUCLEOPHILIC-ADDITION; COUPLING REACTION; ALPHA; ALPHA-DISUBSTITUTED ARYLMETHANOLS; BETA; GAMMA-UNSATURATED KETONES;
D O I
10.1246/bcsj.82.778
中图分类号
O6 [化学];
学科分类号
0703 ;
摘要
Metal-mediated or -catalyzed retro-allylation of homoallyl alcohol that proceeds via a six-membered transition state has appeared as a new useful method to prepare allylmetals. A crotylzirconium reagent undergoes stereoselective allylation of aromatic aldehyde at -78 and 25 degrees C to provide threo- and erythro-homoallyl alcohols, respectively. Although the threo isomer is formed as usual via a six-membered chair transition state under kinetic control, the erythro selectivity is rationalized by considering isomerization of the threo adduct through a retro-allylation process. The retro-allylation of a bulky gallium homoallyloxide occurs to generate (Z)- and (E)-crotylgallium reagents stereospecifically, starting from erythro- and threo-homoallyl alcohols, respectively. The (Z)- and (E)-crotylgallium reagents react with aromatic aldehydes in situ to afford the corresponding erythro- and threo-homoallyl alcohols, respectively. Treatment of rationally designed tertiary homoallyl alcohols with aryl halides under palladium catalysis yielded the corresponding allylarenes stereo- and regioselectively, by replacing the conventional transmetalation step in the cross-coupling reaction with alkoxide-halide exchange followed by a retro-allylation reaction. The retro-allylation reaction is also applicable to nickel and rhodium at this stage, and may to any other metals in principle. Reversible additions of pentamethylcyclopentadienyl anion to carbonyl compounds are also described.
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页码:778 / 792
页数:15
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