Pd-Catalyzed Regioselective C–H Alkenylation and Alkynylation of Allylic Alcohols with the Assistance of a Bidentate Phenanthroline Auxiliary

Abstract

A Pd-catalyzed regioselective C–H alkenylation of allylic alcohols with electron-deficient alkenes has been developed. The key to success is the introduction of bidentately coordinating phenanthroline directing group, which enables the otherwise challenging and regioselective C–H activation at the proximal alkenyl C–H bonds over the conceivably competitive allylic C–O bond activation. The same Pd/phenanthroline system is efficient for the C–H alkynylation of allylic alcohols with alkynyl bromides.

Palladium‐Catalyzed Alkynylation of Alkenes via C−H Activation for the Preparation of Conjugated 1,3‐Enynes

“…Sarpong developed β ‐carboline amide directed, Pd‐catalyzed C−H alkynylation, but with only one example of cyclic ethanamine [15b] . Miura and Hirano studied the Pd‐catalyzed, phenanthroline directed, C−H alkynylation of allylic alcohols [15d] . Very recently, Carreira and coworkers used a more general C−H alkynylation strategy by using picoline as the directing group [15c] .…”

Iridium(III)-Catalyzed Branch-Selective C–H Alkenylation of Aniline Derivatives with Alkenes

“…The significance of oxidative C–H alkenylation reactions with alkenes to form C–C bonds via dual C–H bond activation, which is referred to as the Fujiwara–Moritani reaction, is in widespread use because of its high atom and step economy . Various transition metals, such Pd, Rh, Ru, and Ir have been extensively used as catalysts in such C–H alkenylation reactions mainly using a directing group strategy (Scheme a) . Despite the remarkable successes in linear-selective C–H alkenylation, the synthesis of branched alkenes via branch-selective C–H alkenylation has remained undeveloped.…”

Mechanistic Studies of Pd(II)-Catalyzed E/Z Isomerization of Unactivated Alkenes: Evidence for a Monometallic Nucleopalladation Pathway

“…To the best of our knowledge, a detailed study of Pd­(II)-catalyzed alkene E / Z isomerization of electronically neutral alkenes, without complication by alkene migration, has not been carried out. Moreover, there is a lack of in-depth studies on isomerization reactions that employ Pd­(II) precatalysts bearing carboxylate ligands, which are among the most widely used palladium species in organic synthesis . We were interested in utilizing the system shown in Scheme , given that the alkene is nonconjugated and the catalyst does not contain a chloride counteranion, to study this common, yet surprisingly uncharacterized, process.…”