Indium-Mediated, Highly Efficient and Diastereoselective Addition of Cyclic Secondary Allylic Bromides to Carbonyl Compounds
作者:Faiz Ahmed Khan、B. Prabhudas
DOI:10.1016/s0040-4020(00)00672-4
日期:2000.9
Indium-mediated addition of 3-bromocyclohexene and 3-bromocyclooctene to a variety of aromatic aldehydes and cyclohexanone proceeds smoothly with excellent syn diastereoselectivity to produce the corresponding cycloalkenyl substituted homoallylic alcohols in good to high yields.
homoallylic alcohols in good to excellent yields with high diastereoselectivities (>99:1 dr). Reversed diastereoselectivity was obtained when carbonylsubstrate (e. g., 2‐pyridinecarboxaldehyde, glyoxylic acid) containing chelating substituent was used in the allylation reaction. In addition, the reactions involving acyclic (E)‐cinnamyl bromide as substrate worked equally well with high diastereocontrol.
reactions of carbonylcompounds 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
发现在化学计量的氯化锂和催化量的GaCl 3(20 mol%)存在下,铅有效地介导了羰基化合物与环状烯丙基卤化物的烯丙基化反应,从而以中等收率和高收率得到了所需的均丁醇。出色的非对映控制(> 99:1 syn / anti)和良好的官能团耐受性。相反,使用2-吡啶羧醛作为羰基底物或使用(E)-肉桂基溴化物作为烯丙基化剂产生具有相反的非对映选择性(> 99:1抗/ syn)的相应产物。
Diethylzinc‐Mediated Allylation of Carbonyl Compounds Catalyzed by [(NHC)(PR
<sub>3</sub>
)PdX
<sub>2</sub>
] and [(NHC)Pd(η
<sup>3</sup>
‐allyl)Cl] Complexes
作者:Alexandre Flahaut、Krimo Toutah、Pierre Mangeney、Sylvain Roland
DOI:10.1002/ejic.200900891
日期:2009.12
reaction was investigated with this complex. [(IMesMe)(PPh3)PdI2] catalyzes the allylation of aromatic (except 4-nitrobenzaldehyde) and aliphatic aldehydes (including enolizable aldehydes) with cinnamyl acetate to give the corresponding homoallylic alcohols in 57–98 % yields and diastereoselectivities ranging from 70:30 to 92:8. The allylation of acetone also takes place under the same conditions, leading
Asymmetric allylation of aryl aldehydes: studies on the scope and mechanism of the palladium catalysed diethylzinc mediated umpolung using phosphoramidite ligands
作者:Gareth P. Howell、Adriaan J. Minnaard、Ben L. Feringa
DOI:10.1039/b518165h
日期:——
Using modular, monodentate phosphoramidite ligands, enantioselective palladium catalysed diethylzinc mediated allylation of aldehydes was achieved. The scope of the asymmetric C–C bond formation was investigated with respect to nucleophilic and electrophilic components and an alternative reaction mechanism is proposed based on our findings.