Two new palladium catalyzed cascade reactions involving a 4-exo-dig cyclocarbopalladation are described. These processes are shown to convert bromoenediynes and bromodienynes into strained aromatic compounds in a single step.
Palladium-Catalyzed Enantioselective Heck Alkenylation of Acyclic Alkenols Using a Redox-Relay Strategy
作者:Harshkumar H. Patel、Matthew S. Sigman
DOI:10.1021/ja5130836
日期:2015.3.18
carbonyl group in high enantioselectivity. The success of this reaction is attributed to the use of electron-withdrawing alkenyl triflates, which offer selective β-hydride elimination followed by migration of the catalyst through the alkyl chain to give the alkenylated carbonyl products. The synthetic utility of the process is demonstrated by a two-step modification of a reaction product to yield a tricyclic
Palladium‐Catalyzed Enantioselective Alkenylation of Enelactams Using a Relay Heck Strategy
作者:Qianjia Yuan、Matthew S. Sigman
DOI:10.1002/chem.201902813
日期:2019.8.14
In this report, a palladium-catalyzed redox-relay Heck process to access optically active alkenylated α,β-unsaturated lactams is described. Under mildreaction conditions, electron-deficient alkenyl triflates and electron-rich alkenyliodoniumsalts undergo enantioselective and site-selective coupling with enelactams to deliver the products in high yields and excellent enantioselectivities. Furthermore
Cyclocarbopalladation/Stille Cascade: Stereoselective Access to Quaternary Functionalized Carbons
作者:Océane Flores、Patrick Wagner、Jean Suffert
DOI:10.1021/acs.orglett.1c02400
日期:2021.8.20
afforded someunexpected results. The search for a way to produce seven-membered ring systems led to polycyclic molecules bearing a tetrasubstituted carbon. The triple bond that substitutes the cyclohexene ring on the starting compound is crucial for a high stereoselectivity. This observation has been confirmed by the reaction of a nonsubstituted cyclohexene ring resulting in poor stereoselectivity and
Palladium-catalyzedcross-couplingreactions of 2-bromocyclohex-1-enyl triflates 7 and 11 with a variety of alkenylstannanes occurred chemoselectively at the site of the triflate leaving group to give bromobutadienes which readily underwent Heck reactions with acrylates and styrene. Both steps could be performed in the same flask to give differentially functionalized hexatrienes in up to 88% overall