2497-23-6Relevant academic research and scientific papers
Ni- and pd-catalyzed synthesis of substituted and functionalized allylic boronates
Zhang, Ping,Roundtree, Ian A.,Morken, James P.
supporting information; scheme or table, p. 1416 - 1419 (2012/06/01)
Two highly efficient and convenient methods for the synthesis of functionalized and substituted allylic boronates are described. In one procedure, readily available allylic acetates are converted to allylic boronates catalyzed by Ni/PCy3 or Ni/PPh3 complexes with high levels of stereoselectivity and in good yields. Alternatively, the borylation can be accomplished with commercially available Pd catalysts [e.g., Pd 2(dba)3, PdCl2, Pd/C], starting with easily accessed allylic halides.
Allylic C-H acetoxylation with a 4,5-diazafluorenone-ligated palladium catalyst: A ligand-based strategy to achieve aerobic catalytic turnover
Campbell, Alison N.,White, Paul B.,Guzei, Ilia A.,Stahl, Shannon S.
supporting information; experimental part, p. 15116 - 15119 (2011/01/06)
Pd-catalyzed C-H oxidation reactions often require the use of oxidants other than O2. Here we demonstrate a ligand-based strategy to replace benzoquinone with O2 as the stoichiometric oxidant in Pd-catalyzed allylic C-H acetoxylation. Use of 4,5-diazafluorenone (1) as an ancillary ligand for Pd(OAc)2 enables terminal alkenes to be converted to linear allylic acetoxylation products in good yields and selectivity under 1 atm O 2. Mechanistic studies have revealed that 1 facilitates C-O reductive elimination from a π-allyl-PdII intermediate, thereby eliminating the requirement for benzoquinone in this key catalytic step.
Mechanistic investigations of bipyrimidine-promoted palladium-catalyzed allylic acetoxylation of olefins
Lin, Bo-Lin,Labinger, Jay A.,Bercaw, John E.
experimental part, p. 264 - 271 (2009/10/23)
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.
Catalytic intermolecular linear allylic C-H amination via heterobimetallic catalysis
Reed, Sean A.,White, M. Christina
, p. 3316 - 3318 (2008/10/09)
A novel heterobimetallic Pd(II)sulfoxide/(salen)Cr(III)Cl-catalyzed intermolecular linear allylic C-H amination (LAA) is reported. This reaction directly converts densely functionalized α-olefin substrates (1 equiv) to linear (E)-allylic carbamates with good yields and outstanding regio- and stereoselectivities (>20:1). Chiral bis-homoallylic and homoallylic oxygen, nitrogen, and carbon substituted α-olefins undergo allylic C-H amination with good yields, excellent selectivities, and no erosion in enantiomeric purity. Streamlined routes to (E)-allylic carbamates that can be further elaborated to medicinally and biologically relevant allylic amines are also demonstrated. Valuable 15N-labeled allylic amines may be generated directly from allyl moieties at late stages of synthetic routes by using the readily available 15N-(methoxycarbonyl)-p-toluenesulfonamide nucleophile. Evidence is provided that this reaction proceeds via a heterobimetallic mechanism where Pd/sulfoxide mediates allylic C-H cleavage to form a π-allylPd intermediate, and (salen)Cr(III)Cl/BQ work together to promote functionalization with the nitrogen nucleophile. Copyright
Serial ligand catalysis: A highly selective allylic C-H oxidation
Chen, Mark S.,Prabagaran, Narayanasamy,Labenz, Nathan A.,White, M. Christina
, p. 6970 - 6971 (2007/10/03)
We are reporting a mild, chemo-, and highly regioselective Pd(II)-catalyzed allylic oxidation of α-olefins to furnish branched allylic esters that proceeds via a novel serial ligand catalysis mechanism in which two different ligands (i.e., vinyl sulfoxide 2 and BQ) interact sequentially with the metal to promote distinct steps of the catalytic cycle (i.e., C-H cleavage and π-allyl functionalization, respectively). Copyright
Regiospecific Preparation of Primary Allyl Acetates (2-Alkenyl Acetates)
Martinez, Antonio Garcia,Villalobos, Angeles Cruces,Ruiz, Manuel Oliver
, p. 58 - 60 (2007/10/02)
The reaction of primary, secondary and tertiary allyl alcohols 1 with anhydrous magnesium iodide in benzene gives regiospecifically the primary allyl iodides 2.The corresponding primary allyl acetates 3 are obtained regiospecifically by reaction of 2 with anhydrous sodium acetate in dimethylformamide.
Herstellung und Isomerisierung von 1-Alken-3-yl-acetaten und 2-Alken-1-yl-acetaten
Garcia Martinez, Antonio,Oliver Ruiz, Manuel,Contelles, Jose Luis Marco
, p. 125 - 128 (2007/10/02)
The allylic rearrangement of 1-alken-3-yl acetates in acetic acid containing sodium acetate proceeds at a slower rate but in higher yield than the rearrangement in the presence of strong proton acids.The predominant products are 2-alken-1-yl acetates. (E)-2-Hexen-1-yl acetate can be isomerized to the (Z)-isomer or rearranged to 1-hexen-3-yl acetate via the epoxide, depending upon the conditions of reduction of the epoxide.
Manganese(III)-Mediated γ-Lactone Annulation
Fristad, William E.,Peterson, John R.
, p. 10 - 18 (2007/10/02)
The annulation of a γ-lactone ring onto an alkene by manganese(III) acetate oxidation of acetic acid was investigated.The regioselectivity of addition to unsymmetrically substituted alkenes is reported along with the stereoselectivity of addition to various acyclic and cyclic alkenes.Alkenes with ionization potentials above 8.2 eV were found to react in good yield.The role of acetic anhydride in these reactions was studied, and it was shown to be oxidized faster than acetic acid and also led to different products.The fate of oxidized acetic acid or anhydridein the absence of suitable acceptor molecule has also been quantitatively identified.The relationship of enolizability, or C-H acidity, of the carboxylic acid being oxidized was established quantitatively.
