85989-62-4Relevant academic research and scientific papers
Catalytic substitution/cyclization sequences of: O -substituted Isocyanates: Synthesis of 1-alkoxybenzimidazolones and 1-alkoxy-3,4-dihydroquinazolin-2(1 H)-ones
Wang, Qiang,An, Jing,Alper, Howard,Xiao, Wen-Jing,Beauchemin, André M.
, p. 13055 - 13058 (2017)
O-Substituted isocyanates (O-isocyanates) have rarely been used in organic synthesis, given their tendency to undergo side reactions (e.g., trimerization). Herein, we show that masked (blocked) O-isocyanate precursors allow one-pot or cascade reaction sequences featuring base-catalyzed substitution with 2-iodoanilines and 2-iodobenzylamines followed by copper-catalyzed cyclization, to form benzimidazolones and 3,4-dihydroquinazolin-2(1H)-ones. This work shows that O-isocyanates can serve as efficient building blocks for the synthesis of hydroxylamine-containing heterocycles.
KINETICS AND MECHANISM OF HYDROLYSIS OF ARYL N-METHOXYCARBAMATES AND THEIR DERIVATIVES
Mindl, Jaromir,Sterba, Vojeslav
, p. 900 - 905 (2007/10/02)
Hydrolysis kinetics have been studied of 3- and 4-substituted phenyl N-methoxycarbamates and their N-methyl derivatives in aqueous buffers at 60 deg C.The N-methyl derivatives show linear dependence of the rate constants on concentration of hydroxyl ion in the pH range measured.Hydrolysis of aryl N-methoxycarbamates is independent of hydroxyl ion concentration at higher pH values.Logarithms of the rate constants have been correlated with the substituent constants ?.The calculated values 0.9 for N-methyl derivatives, 4.5 and 3.3 for aryl N-methoxy-carbamates in theregions of linear pH-dependency and pH-independency, respectively, suggest that the hydrolysis follows the BAc2 and ElcB mechanisms in the case of the N-methyl derivatives and aryl N-methoxycarbamates, respectively.Difference between the two ρ constants for the hydrolysis of aryl N-methoxycarbamates agrees with the found value ρ=1.2 for dissociation constants of these compounds.The elimination mechanism has been confirmed by reaction of the isocyanate formed with added aniline to give the respective urea.
