Nickel-Catalyzed Enantioselective Synthesis of Pre-Differentiated Homoallylic <i>syn</i>- or <i>anti</i>-1,2-Diols from Aldehydes and Dienol Ethers
作者:Thomas Q. Davies、John J. Murphy、Maxime Dousset、Alois Fürstner
DOI:10.1021/jacs.1c07042
日期:2021.9.1
Nickelcatalysis allied with cyclodiphosphazane or VAPOL-derived phosphoramidite ligands provides selective access to monoprotected vicinal diols by reductive coupling of dienol ethers and aldehydes. The observed regioselectivity is unprecedented, in that the diene reacts at the least nucleophilic and most hindered C atom that is attached to the oxygen substituent rather than at the terminal position
镍催化与环二磷氮烷或 VAPOL 衍生的亚磷酰胺配体结合,通过二烯醇醚和醛的还原偶联提供对单保护的邻二醇的选择性访问。观察到的区域选择性是前所未有的,因为二烯在亲核性最低且受阻最大的 C 原子上反应,该 C 原子连接到氧取代基而不是在末端位置。值得注意的是,产品的顺式和反式非对映异构体都可以根据二烯伙伴的配置获得,通常具有出色的非对映选择性和对映选择性。
Regioselective Rhodium-Catalyzed Hydroformylation of 1,3-Dienes to Highly Enantioenriched β,γ-Unsaturated Aldehyes with Diazaphospholane Ligands
作者:Avery L. Watkins、Clark R. Landis
DOI:10.1021/ol102797t
日期:2011.1.7
Regioselective and enantioselective rhodium-catalyzed hydroformylation of 1,3-dienes with chiral bisdiazaphospholane ligands yields β,γ-unsaturated aldehydes that retain a C═C functionality for further conversion. The reaction conditions are mild, featuring low catalyst loadings (0.5 mol %), pressures readily obtained in glass bottles, and convenient reaction times (1.5−12 h). Optimized reaction conditions
good to excellent yields. Alkenes react with 2 with complete retention of configuration. The [2+2] cycloaddition is concluded to proceed via a concerted [(pi(2s)+pi(2s))(allene) + pi(2s)] Huckel transition state on the basis of experimental evidences and quantum mechanical methods. Some highly polarized enones and nitrile oxide, on the other hand, react with 2 selectively at the internal C(4)=C(alpha)
Ni(acac)(2) catalyzes homoallylation of aldehydes with 1,3-dienes in the presence of triethylborane. Triethylborane serves as a reducing agent delivering a formal hydride to the C2 position of 1,3-dienes, thus generating a formal homoallyl anion species and enabling the novelhomoallylation of aldehydes. The reaction proceeds smoothly at room temperature in the absence of any phosphane or nitrogen
Tandem vinylogous Mannich and hetero Diels-Alder reactions: Concise total synthesis of (±)-Alstoscholarisine E
作者:Michael D. Wood、Daniel W. Klosowski、Stephen F. Martin
DOI:10.1016/j.tet.2021.132150
日期:2021.6
steps from commercially available reagents. The approach features a tandem vinylogous Mannich reaction and an intramolecular heteroDiels-Alderreaction to access the cis-oxahydroisoquinolone core. Following the coupling of this cis-oxahydroisoquinolone subunit with a 3-methylindole derivative via a Suzuki reaction, a novel tactic to induce the challenging diastereoselective reduction of the cyclic vinyl