scholarly journals Mechanistic investigations of bipyrimidine-promoted palladium-catalyzed allylic acetoxylation of olefins

2009 ◽  
Vol 87 (1) ◽  
pp. 264-271 ◽  
Author(s):  
Bo-Lin Lin ◽  
Jay A Labinger ◽  
John E Bercaw
Keyword(s):  
Acetic Acid ◽  
Key Words ◽  
Palladium Catalysis ◽  
Allylic Oxidation ◽  
Competition Experiment ◽  
Catalyst Precursor ◽  
Mechanistic Studies ◽  
Allyl Acetate ◽  
Palladium Catalyzed ◽  
Terminal Olefins

Several pyridine-like ligands were found to improve Pd(OAc)2-catalyzed allylic oxidation of allylbenzene to cinnamyl acetate by p-benzoquinone in acetic acid. The best ligand examined, bipyrimidine, was used to identify the catalyst precursor for this system, (bipyrimidine)Pd(OAc)2, which was fully characterized. Mechanistic studies suggest the reaction takes place through disproportionation of (bipyrimidine)Pd(OAc)2 to form a bipyrimidine-bridged dimer, which reacts with olefin to form a PdII-olefin adduct, followed by allylic C–H activation to produce (η3-allyl)PdII species. The (η3-allyl)PdII intermediate undergoes a reversible acetate attack to generate a Pd0-(allyl acetate) adduct, which subsequently reacts with p-benzoquinone to release allyl acetate and regenerate (bipyrimidine)Pd(OAc)2. No KIE is observed for the competition experiment between allylbenzene-d0 and allylbenzene-d5 (CD2=CDCD2C6H5), suggesting that allylic C–H activation is not rate-determining. Catalytic allylic acetoxylations of other terminal olefins as well as cyclohexene were also effected by (bipyrimidine)Pd(OAc)2.Key words: olefin, palladium catalysis, allylic C–H oxidation, p-benzoquinone, bipyrimidine.

ChemInform Abstract: Palladium-Catalyzed Double Arylations of Terminal Olefins in Acetic Acid.

ChemInform ◽  
2012 ◽  
Vol 43 (27) ◽  
pp. no-no
Author(s):  
Daichao Xu ◽  
Chunxin Lu ◽  
Wanzhi Chen
Keyword(s):  
Acetic Acid ◽  
Palladium Catalyzed ◽  
Terminal Olefins

Palladium-catalyzed double arylations of terminal olefins in acetic acid

Tetrahedron ◽  
2012 ◽  
Vol 68 (5) ◽  
pp. 1466-1474 ◽  
Author(s):  
Daichao Xu ◽  
Chunxin Lu ◽  
Wanzhi Chen
Keyword(s):  
Acetic Acid ◽  
Palladium Catalyzed ◽  
Terminal Olefins

scholarly journals Bipyridylacetylenes 1: the synthesis of some bipyridylacetylenes via the palladium-catalyzed coupling of acetylenes with 2,2′-dibromobipyridyl, and the single crystal X-ray structure of 6,6′-bisphenylethynyl-2,2′-bipyridine

1991 ◽  
Vol 69 (7) ◽  
pp. 1117-1123 ◽  
Author(s):  
Ian R. Butler ◽  
Chantal Soucy-Breau
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Key Words ◽  
Dihedral Angle ◽  
Palladium Catalysis ◽  
Crystal Data ◽  
X Ray ◽  
Acetylenic Bond ◽  
Palladium Catalyzed

The synthesis of a series of 6,6′-diethynyl-2,2′-bipyridyls from the palladium-catalyzed coupling of 6,6′-dibromo-2,2′-bipyridine with a series of arylacetylenes is reported. The single crystal X-ray structure of 6,6′-phenylethynyl-2,2′-bipyridyl was determined. Crystal data: monoclinic, A2/a, with cell constants a = 10.0385(4), b = 9.2166(4), c = 21.4130(8) Å, and β = 102.981(3)°; Dcalc. = 1.226 g cm−3, Z = 4, Rf = 0.045, S = 1.22, using 886 reflections of the 1443 unique reflections. The packing diagram indicates essentially that the molecules pack in a layered assembly with the nitrogen atoms of the dipyridyl groups on opposite sides and with a dihedral angle of 59.85(16)° between the pyridyl and phenyl groups. The acetylenic bond distances are normal. Key words: acetylene, palladium, catalysis, coupling, monomers, crystal structure.

A new palladium-catalyzed coupling reaction of vinylic and allylic triflates with pyrimidine nucleosides

1991 ◽  
Vol 69 (2) ◽  
pp. 198-200 ◽  
Author(s):  
Mohamed Ezeldin Hassan
Keyword(s):  
Key Words ◽  
Palladium Catalysis ◽  
Coupling Reaction ◽  
Pyrimidine Nucleosides ◽  
Mild Conditions ◽  
Palladium Catalyzed ◽  
High Yields

Vinylic trifluoromethane sulfonates (triflates) form palladium intermediates that react with pyrimidine nucleosides to produce C-5 alkyl substituted nucleosides after hydrogenation of the vinylic coupling products with hydrogen and Pd/C in methanol. The reaction, which is run under mild conditions, appears to be a general one since both mono- and disubstituted vinylic triflates, as well as the cyclic ones, gave high yields of the corresponding C-5 alkyl-substituted nucleoside. The reaction with allyl triflate requires the use of the 5-chloromercurinucleoside. Key words: nucleosides, triflates, palladium catalysis

Temporary (PO) directing group enabled carbazole ortho arylation via palladium catalysis

2021 ◽  
Vol 57 (16) ◽  
pp. 2021-2024
Author(s):  
Zhi-Chao Qi ◽  
Qin-Xin Lou ◽  
Yuan Niu ◽  
Shang-Dong Yang
Keyword(s):  
Palladium Catalysis ◽  
Palladium Catalyzed ◽  
Directing Group

An efficient palladium-catalyzed, temporary P(O) directing group assisted C–H bond arylation of carbazoles was achieved, accompanied by the directing group being self-shed spontaneously.

Intermolecular C–H Amidation of Alkenes with Carbon Monoxide and Azides via Tandem Palladium Catalysis

Synthesis ◽  
2021 ◽  
Author(s):  
Zheng-Yang Gu ◽  
Yang Wu ◽  
Feng Jin ◽  
Bao Xiaoguang ◽  
Ji-Bao Xia
Keyword(s):  
Carbon Monoxide ◽  
Palladium Catalysis ◽  
Computational Studies ◽  
Organic Azides ◽  
Reaction Proceeds ◽  
Palladium Catalyzed ◽  
Directing Group ◽  
And Control

An atom- and step-economic intermolecular multi-component palladium-catalyzed C–H amidation of alkenes with carbon monoxide and organic azides has been developed for the synthesis of alkenyl amides. The reaction proceeds efficiently without an ortho-directing group on the alkene substrates. Nontoxic dinitrogen is generated as the sole by-product. Computational studies and control experiments have revealed that the reaction takes place via an unexpected mechanism by tandem palladium catalysis.

Palladium-catalyzed paraformaldehyde insertion: a three-component synthesis of benzofurans

2016 ◽  
Vol 14 (10) ◽  
pp. 2819-2823 ◽  
Author(s):  
Xiufang Cheng ◽  
Yi Peng ◽  
Jun Wu ◽  
Guo-Jun Deng
Keyword(s):  
Palladium Catalysis ◽  
Phenacyl Bromides ◽  
Palladium Catalyzed

2-Aroylbenzofurans were prepared from 2-bromophenols, phenacyl bromides and paraformaldehyde under palladium catalysis conditions.

Synthesis and characterization of the binuclear diamido titanium chalcogenides [(Ar)NCH2CH2CH2N(Ar)]2Ti(µ-E)2 (E = Se, Te)

2002 ◽  
Vol 80 (11) ◽  
pp. 1524-1529 ◽  
Author(s):  
Tianle Zhang ◽  
Warren E Piers ◽  
Masood Parvez
Keyword(s):  
Solid State ◽  
Key Words ◽  
Synthesis And Characterization ◽  
Catalyst Precursor ◽  
Tellurium Atom ◽  
Titanium Complex ◽  
X Ray ◽  
X Ray Crystallography ◽  
Atom Source

Reaction of McConville's chelating amido titanium complex [(Ar)NCH2CH2CH2N(Ar)]Ti(CH3)2 (Ar = 2,6-i-Pr2C6H3) with either elemental Se or the tellurium atom source Te=PBu3 resulted in the formation of bis-µ-chalcogenido dimers [(Ar)NCH2CH2CH2N(Ar)]2Ti(µ-E)2 (E = Se, 2; Te, 3) with concommitant loss of EMe2. The dimers 2 and 3 were characterized spectroscopically and via X-ray crystallography. The two compounds are isostructural in the solid state. The tellurido dimer 3 may also be synthesized by reduction of the diamido dichloride [(Ar)NCH2CH2CH2N(Ar)]2TiCl2 with Na–Hg amalgam followed by treatment with Te=PBu3. This dimer is unreactive toward further Te=PBu3 or stannanes such as HSnBu3. Unlike decamethyltitanocene derivatives, the diamido complex is not an effective catalyst precursor for the heterohydrodecoupling of Te=PBu3 and HSnBu3.Key words: diamido titanium complexes, selenides, tellurides.

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