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。
Nickel-Catalysed Allylboration of Aldehydes
作者:Benjamin M. Partridge、Francesca M. Dennis、Craig C. Robertson
DOI:10.1055/s-0039-1690091
日期:2020.7
A nickel catalyst for the allylboration of aldehydes is reported, facilitating the preparation of homoallylic alcohols in high diastereoselectivity. The observed diastereoselectivities and NMR experiments suggest that allylation occurs through a well-defined six-membered transition state, with nickel acting as a Lewis acid.
Catalytic asymmetric allylation of aldehydes with alkenes through allylic C(sp<sup>3</sup>)–H functionalization mediated by organophotoredox and chiral chromium hybrid catalysis
describe a hybrid system that realizes cooperativity between an organophotoredox acridinium catalyst and a chiral chromium complex catalyst, thereby enabling unprecedented exploitation of unactivated hydrocarbon alkenes as precursors to chiral allylchromium nucleophiles for asymmetricallylation of aldehydes. The reaction proceeds under visible light irradiation at room temperature, affording the corresponding