27064-92-2Relevant academic research and scientific papers
Operando Spectroscopic and Kinetic Characterization of Aerobic Allylic C-H Acetoxylation Catalyzed by Pd(OAc)2/4,5-Diazafluoren-9-one
Jaworski, Jonathan N.,Kozack, Caitlin V.,Tereniak, Stephen J.,Knapp, Spring Melody M.,Landis, Clark R.,Miller, Jeffrey T.,Stahl, Shannon S.
supporting information, p. 10462 - 10474 (2019/07/09)
Allylic C-H acetoxylations are among the most widely studied palladium(II)-catalyzed C-H oxidation reactions. While the principal reaction steps are well established, key features of the catalytic mechanisms are poorly characterized, including the identity of the turnover-limiting step and the catalyst resting state. Here, we report a mechanistic study of aerobic allylic acetoxylation of allylbenzene with a catalyst system composed of Pd(OAc)2 and 4,5-diazafluoren-9-one (DAF). The DAF ligand is unique in its ability to support aerobic catalytic turnover, even in the absence of benzoquinone or other co-catalysts. Herein, we describe operando spectroscopic analysis of the catalytic reaction using X-ray absorption and NMR spectroscopic methods that allow direct observation of the formation and decay of a palladium(I) species during the reaction. Kinetic studies reveal the presence of two distinct kinetic phases: (1) a burst phase, involving rapid formation of the allylic acetoxylation product and formation of the dimeric PdI complex [PdI(DAF)(OAc)]2, followed by (2) a post-burst phase that coincides with evolution of the catalyst resting state from the PdI dimer into a π-allyl-PdII species. The data provide unprecedented insights into the role of ancillary ligands in supporting catalytic turnover with O2 as the stoichiometric oxidant and establish an important foundation for the development of improved catalysts for allylic oxidation reactions.
A Convenient Palladium-Catalyzed Carbonylative Synthesis of (E)-3-Benzylidenechroman-4-ones
Wang, Wei-Feng,Peng, Jin-Bao,Qi, Xinxin,Ying, Jun,Wu, Xiao-Feng
supporting information, p. 3521 - 3524 (2019/02/14)
A convenient palladium-catalyzed carbonylation reaction for the efficient synthesis of (E)-3-benzylidenechroman-4-ones has been developed. Using TFBen as a solid CO source, a range of substituted (E)-3-benzylidenechroman-4-ones were prepared in moderate to good yields with 2-iodophenols and allyl chlorides as the substrates. Additionally, substituted quinolin-4(1H)-ones can also be obtained with 2-iodoaniline as the starting material.
PdII/Novel Chiral Cinchona Alkaloid Oxazoline-Catalyzed Enantioselective Oxidative Cyclization of Aromatic Alkenyl Amides
Tian, Qinqin,Liu, Yulong,Wang, Xiaoyun,Wang, Xie,He, Wei
supporting information, p. 3850 - 3855 (2019/06/08)
A highly enantioselective PdII-catalyzed aza-Wacker oxidation tandem cyclization of aromatic nitrogen-containing dienes has been achieved in the presence of novel chiral cinchona alkaloid oxazoline ligands for the first time, affording chiral dihydroindole nitrogen-containing polycyclic compounds with good yields (up to 83 %), high diastereoselectivities (> 95:5 dr), and excellent enantioselectivities (up to 97 % ee).
Selectfluor-mediated mild oxidative halogenation and thiocyanation of 1-aryl-allenes with TMSX (X = Cl, Br, I, NCS) and NH4SCN
Laali, Kenneth K.,Nandi, Ganesh C.,Bunge, Scott D.
supporting information, p. 2401 - 2405 (2014/05/06)
Presence of TMSX (X = Cl, Br, I) unleashes the oxidative character of Selectfluor and provides a mild dihalogenation method for 1-arylallenes. Preference for 2,3-addition was observed with TMSCl in MeCN irrespective of the nature of the substituent on the aryl moiety, whereas 1,2-addition was preferred in [BMIM][BF4]. With TMSBr and TMSI only products corresponding to 2,3-addition were observed. Reactions carried out with TMSBr in IL solvents gave the corresponding monobromoalkenes as a major product along with the isomeric dibromo-alkenes. Reaction with NH4SCN provided convenient access to dithiocyanate derivatives. The same products were formed via TMS-NCS/Selectfluor. Formation of common products via TMSNCS and NH 4SCN points to the formation and interplay of SCN+/ NCS+ as incipient electrophiles.
One-pot synthesis of functionalized p-terphenyl derivatives
Chang, Meng-Yang,Chan, Chieh-Kai,Wu, Ming-Hao
, p. 7916 - 7924 (2013/08/23)
A one-pot synthetic route for preparing functionalized p-terphenyl derivatives 1 and 4 is developed. The route is easily carried from the treatment of cinnamyl aldehydes 2 with substituted allylsulfones 3 in good yields via the tandem intermolecular aldol condensation/intramolecular electrocyclization/ oxidative dehydrogenation.
