90564-02-6Relevant academic research and scientific papers
Pd-Catalyzed Asymmetric Dearomatization of Indoles via Decarbonylative Heck-Type Reaction of Thioesters
Han, Ming-Liang,Huang, Wei,Liu, Yu-Wen,Liu, Min,Xu, Hui,Xiong, Hai,Dai, Hui-Xiong
supporting information, p. 172 - 177 (2021/01/09)
We report herein a palladium-catalyzed ligand-promoted asymmetric dearomatization of indoles via the decarbonylation of thioesters and the subsequent reductive Heck reaction. This protocol provides a facile and efficient way to construct an aza-quaternary stereocenter at the C2 position of indolines. A variety of functional groups and substitutions could be well tolerated, affording the substituted indolines with high enantioselectivities.
Effects of CH3OH-H2O and CH3OH Solvents on Rate of Reaction of Phthalimide with Piperidine
Khan, M. Niyaz
, p. 29 - 40 (2007/10/03)
Pseudo-first-order rate constants (κobs) for the cleavage of phthalimide in the presence of piperidine (Pip) vary linearly with the total concentration of Pip ([Pip]-) at a constant content of methanol in mixed aqueous solvents containing 2 percent v/v acetonitrile. Such linear variation of κobs against [Pip]t exists within the methanol content range 10 percent - 80 percent v/v. The change in κobs with the change in [Pip]t at 98 percent v/v CH3OH in mixed methanol-acetonitrile solvent shows the relationship: κobs = Sknapp[Pip]t + kgbapp[Pip]t2, where respective Sknapp and kgbapp represent apparent second-order and third-order rate constants for nucleophilic and general base-catalyzed piperidinolysis of phthalimide. The values of κobs obtained within [Pip]t range 0.02-0.40 M at 0.03 M NaOH and 20 as well as 50 percent v/v CH3OH reveal the relationship: κobs = κ0/(1+[κn(Pip)]/κox[-OX]t), where κ0 is the pseudo-first-order rate constant for hydrolysis of phthalimide, κn and κox represent nucleophilic second-order rate constants for the reaction of Pip with phthalimide and for the XO--catalyzed cyclization of N-piperidinylphthalamide to phthalimide, respectively, and [-OX]t) = [NaOH] + [-OXre], where [-OXre] = [-OHre] + [CH3Ore-]. The reversible reactions of Pip with H2O and CH3OH produce -OHre and CH3Ore- ions. The effects of mixed methanol-water solvents on the rates of piperidinolysis of PTH reveal a nonlinear decrease in κnapp with the increase in the content of methanol.
O-Methylarenehydroxamates as Ortho-Lithiation Directing Groups. Ti(III)-Mediated Conversion of O-Methyl Hydroxamates to Primary Amides
Fisher, Lawrence E.,Caroon, Joan M.,Jahangir,Stabler, S. Russell,Lundberg, Scott,Muchowski, Joseph M.
, p. 3643 - 3647 (2007/10/02)
Reaction of O-methyl benzohydroxamates 2a-c with sec-butyllithium in the presence of TMEDA at -40 deg C regiospecifically generates the highly reactive N,ortho-dilithiated species (e.g. 3).These dilithio species react avidly with a wide spectrum of electrophilic reagents, including alkyl halides, givind adducts which on reduction with TiCl3 are converted into ortho-substituted primary benzamides in excellent yields.Ortho lithiation of O-methyl benzohydroxamates is thus formally equivalent to ortho lithiation of primary benzamides themselves.The utility of these synthetic operations is enhanced by the well-known facility with wich the primary amide moiety can be transformed into other useful functional groups.The conversion of O-methyl hydroxamates to primary amides is shown to be general, as exemplified by transformation of 14a-f to 15a-f.O-Methyl-2-methylbenzohydroxamate (4a) undergoes regiospecific dilithiation on nitrogen and on the methyl group when treated with sec-butyllithium at -70 deg C.These dilithio species react with DMF or "Weinreb-type" amides to give condensation products wich cyclize to N-methoxyisoquinolin-1(2H)-ones under mildly acidic conditions.Removal of the N-methoxy moiety under conditions analogous to those used for O-methyl benzohydroxamate provides N-unsubstituted isoquinolin-1(2H)-ones with high overall efficiency.This process is exemplified by the synthesis of isoquinolin-1(2H)-one 9a, its 3-n-butyl congener 9b, and the tricyclic isoquinolin-1(2H)-ones 20a and 20b from O-methyl 2-methylbenzohydroxamate (4a).
