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Palladium‐Catalyzed Reductive Coupling Reaction of Terminal Alkynes with Aryl Iodides Utilizing Hafnocene Difluoride as a Hafnium Hydride Precursor Leading to trans ‐Alkenes
Author(s) -
Takahashi Keita,
Ogiwara Yohei,
Sakai Norio
Publication year - 2018
Publication title -
chemistry – an asian journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 106
eISSN - 1861-471X
pISSN - 1861-4728
DOI - 10.1002/asia.201701775
Subject(s) - chemistry , reductive elimination , aryl , palladium , alkyne , catalysis , cyclopentadienyl complex , medicinal chemistry , hydride , transmetalation , reagent , difluoride , alkyl , catalytic cycle , organic chemistry , hydrogen
Herein, we describe a reductive cross‐coupling of alkynes and aryl iodides by using a novel catalytic system composed of a catalytic amount of palladium dichloride and a promoter precursor, hafnocene difluoride (Cp 2 HfF 2 , Cp=cyclopentadienyl anion), in the presence of a mild reducing reagent, a hydrosilane, leading to a one‐pot preparation of trans ‐alkenes. In this process, a series of coupling reactions efficiently proceeds through the following three steps: (i) an initial formation of hafnocene hydride from hafnocene difluoride and the hydrosilane, (ii) a subsequent hydrohafnation toward alkynes, and (iii) a final transmetalation of the alkenyl hafnium species to a palladium complex. This reductive coupling could be chemoselectively applied to the preparation of trans ‐alkenes with various functional groups, such as an alkyl group, a halogen, an ester, a nitro group, a heterocycle, a boronic ester, and an internal alkyne.