87258-45-5Relevant academic research and scientific papers
Rhodium-Catalyzed Annulation of Phenacyl Ammonium Salts with Propargylic Alcohols via a Sequential Dual C-H and a C-C Bond Activation: Modular Entry to Diverse Isochromenones
Nanubolu, Jagadeesh Babu,Reddy Singam, Maneesh Kumar,Sridhar Reddy, Maddi,Suresh, Vavilapalli,Suri Babu, Undamatla
, p. 7888 - 7893 (2021/10/25)
Given their omnipresence in natural products and pharmaceuticals, isochromenone congeners are one of the most privileged scaffolds to synthetic chemists. Disclosed herein is a dual (ortho/meta) C-H and C-C activation of phenacyl ammonium salts (acylammonium as traceless directing group) toward annulation with propargylic alcohols to accomplish rapid access for novel isochromenones by means of rhodium catalysis from readily available starting materials. This operationally simple protocol features broad substrate scope and wide functional group tolerance. Importantly, the protocol circumvents the need of any stoichiometric metal oxidants and proceeds under aerobic conditions.
Rhodium-Catalyzed Spiro Indenyl Benzoxazine Synthesis via C-H Activation/Annulation of 3-Aryl-2H-Benzo[b][1,4]oxazines and Alkynes
Tan, Heng,Laishram, Ronibala Devi,Zhang, Xuexin,Shi, Guangrui,Li, Kangkui,Chen, Jingchao
, p. 4542 - 4546 (2020/07/04)
The rhodium (III)-catalyzed annulation of 3-Aryl-2H-Benzo[b][1,4]oxazines with alkynes via C–H activation has been developed. This reaction afforded a series of spiro indenyl benzoxazine in high yields under mild reaction condition with good functional group tolerance.
Palladium-catalyzed chelation-assisted aromatic C-H nitration: Regiospecific synthesis of nitroarenes free from the effect of the orientation rules
Zhang, Wei,Lou, Shaojie,Liu, Yunkui,Xu, Zhenyuan
, p. 5932 - 5948 (2013/07/26)
A palladium-catalyzed chelation-assisted ortho-nitration of aryl C-H bond is described. A range of azaarenes such as 2-arylquinoxalines, pyridines, quinoline, and pyrazoles were nitrated with excellent chemo- and regioselectivity. Using the O-methyl oximyl group as a removable directing group, the regiospecific synthesis of a variety of o-nitro aryl ketones was achieved starting from aryl ketones via a three-step process involving the Pd-catalyzed ipso-nitration of C-H bond as a key step. Mechanistic investigations support a silver-mediated radical mechanism involving Pd((II/III) and/or Pd(II/IV) catalytic cycles under oxidizing conditions.
Regiospecific synthesis of nitroarenes by palladium-catalyzed nitrogen-donor-directed aromatic C-H nitration
Liu, Yun-Kui,Lou, Shao-Jie,Xu, Dan-Qian,Xu, Zhen-Yuan
, p. 13590 - 13593 (2011/03/18)
Nitration of N-heteroaromatics: The first example of palladium-catalyzed direct ortho-nitration of aryl C-H bonds is described. A range of azaarenes, such as 2-arylquinoxalines, pyridines, pyrazoles, and O-methyl oximes, were nitrated with excellent chemo- and regioselectivity (see scheme; DCE=1,2-dichloroethane). Preliminary mechanistic investigations support a silver-mediated radical mechanism involving palladium(II/III) and/or palladium(II/IV) catalytic cycles under oxidizing conditions. Copyright
The Mechanism of Two Reactions leading to Isomeric 2-(N,N-Disubstituted Amino)thiazol-5-yl Ketones
Challacombe, Katherine,Leach, Susan E.,Plackett, Simon J.,Meakins, G. Denis
, p. 2213 - 2218 (2007/10/02)
A study has been made of the condensations between N-acyl-N',N'-disubstituted thioureas and α-halogeno ketones , and between N,N-disubstituted thioureas and 2-bromo-1,3-diketones .The mechanistic details were elucidated by usi
ON THE MECHANISM OF THE DECARBOXYLATIVE REARRANGEMENT OF THIOHYDROXAMIC ESTERS
Barton, Derek H.R.,Crich, David,Potier, Pierre
, p. 5943 - 5946 (2007/10/02)
The thermal and photochemical decomposition of a typical thiohydroxamic ester (mixed anhydride) doubly labelled with deuterium has shown the photochemical reaction to be a radical chain process, whereas about 20percent of the thermal reaction involves a cage mechanism.An improved route to 1-hydroxy-5-phenylthiazolin-2-thione is reported.
Base Catalysed Rearrangements involving Ylide Intermediates. Part 15. The Machanism of the Stevens Rearrangement
Ollis, W. David,Rey, Max,Sutherland, Ian O.
, p. 1009 - 1027 (2007/10/02)
The Stevens rearrangement of acyl-stabilised ammonium ylides has been investigated with regard to stereoselectivity, intramolecularity and the formation of products in addition to the rearrangement product.A detailed study of the effects of reaction conditions upon the rearrangement of the ylide derived from the salt (13) has shown that the stereoselectivity (retention of the configuration of the chiral migrating group) and intramolecularity decrease as solvent viscosity decreases.The rearrangement of the salt (13) in water at 0 deg C is essentially intramolecular with virtually complete retention of the configuration of the migrating group.These results, together with the isolation of products that can be rationalised on the basis of random free-radical coupling, indicate that the rearrangement of acyl-stabilised ammonium ylides normally involves a radical pair mechanism.
