Branch Selective Murai-type Alkene Hydroarylation Reactions

Abstract

There is significant interest in the development of CC bondforming methodologies that directly access challenging benzylic stereocenters. Predominantly, efforts have been focused on the development of enantiospecific or enantioselective crosscoupling methodologies. An alternate and conceptually ideal approach involves the development of branch-selective and enantioselective Murai-type alkene hydroarylations. Recent progress towards this broad, yet challenging goal is highlighted.

Branched‐Selective Direct α‐Alkylation of Cyclic Ketones with Simple Alkenes

“…Stimulated by the challenge of ketone alkylation with alkenes for yielding β‐branched products, our laboratory has recently devised a stepwise enamide‐based strategy that enables a net ketone α‐alkylation with simple alkenes in high branched selectivity . In this approach, 5‐membered lactams were employed as the directing template to pre‐form enamides with ketones, which further undergo Ir‐catalyzed branched‐selective coupling with alkenes . Further hydrolysis of the enamide‐alkylation products affords ketone α‐alkylation products.…”

Iridium‐Catalyzed Regio‐ and Enantioselective Hydroarylation of Alkenyl Ethers by Olefin Isomerization

“…[1] Thepioneering studies on the transition-metal-catalyzed alkene hydroarylation by Murai and co-workers have described high linear selectivity in the reaction with terminal alkenes. [1b] Recently,b ranchselective hydroarylation [2] has also emerged for vinylarenes, [3] vinyl ethers, [4] and simple alkenes. [5] Although the regiocontrolled hydroarylation reactions of terminal alkenes leading to chiral molecules have been developed, the use of ac hiral catalyst for this asymmetric transformation remains to be studied.…”

Jenseits von Friedel und Crafts: dirigierte Alkylierung von C‐H‐Bindungen in Arenen

“…[48] Mit aktivierten Alkenen wie Acrolein oder konjugierten Ketonen entwickelten Li et al ein auf eine Carboxylatfunktion erweitertes, [49] Zusätzlich zu Ruthenium-und Rhodiumkomplexen sowie einem einzigen Beispiel füre inen Iridiumkatalysator zur Alkylierung eines Iminoferrocens [51] führten Gao und Yoshikai verschiedene Cobaltkatalysatoren [52] fürd ie ortho-Alkylierung aromatischer Imine ein. Bei der Reaktion mit katalytischen Mengen an Cobalt(II)-bromid, 1,10-Phenanthrolin und einem Grignard-Reagens werden verschiedene Imine problemlos mit einer Auswahl an Alkenen zu den entsprechenden linearen (L-)Produkten alkyliert, mit Ausnahme von Styrolderivaten, die überwiegend verzweigte (B-)Isomere [53] ergeben [Schema 10, Gl. (1)].…”