Multilevel Selectivity in the Mild and High-Yielding Chlorosilane-Induced Cleavage of Carbamates to Isocyanates
摘要:
The silane-induced cleavage of a series of N-p-tolylcarbamates and N-phenethylcarbamates to isocyanates has been investigated as a function of chlorosilane, carbamate substituent, and reaction conditions. Reaction yields were determined from the isolated ureas, which were formed by trapping the Corresponding isocyanates with isobutylamine. Under room-temperature conditions, multilevel selectivity in carbamate activation has been demonstrated. This selectivity together with the generality of the methodology enhances the utility of carbamates as synthetic intermediates and protecting groups. To demonstrate the effectiveness of this selectivity, a series of biscarbamates were selectively monoactivated to isocyanates in excellent yields.
Synthesis of alkyl, aryl, heterocyclic, carbohydrate and amino acid carbamates is described. The protection of the amino group in the presence of other functionality in amino acids demonstrates the importance of this method. (C) 1998 Elsevier Science Ltd. All rights reserved.
Activation of 2-Alkenoic Acids as Mixed Anhydrides with Diphenylphosphinic Acid for the Formation of Carboxamides
The Synthesis of N-Substituted Carbamates<sup>1</sup>
作者:R. L. Shriner、Ralph G. Child
DOI:10.1021/ja01122a082
日期:1952.1
BERNASCONI S.; COMINI A.; CORBELLA A.; GARIBOLDI P.; SISTI M., SYNTHESIS, 1980, NO 5, 385-387
作者:BERNASCONI S.、 COMINI A.、 CORBELLA A.、 GARIBOLDI P.、 SISTI M.
DOI:——
日期:——
Urethanes synthesis from oxamic acids under electrochemical conditions
作者:Ikechukwu Martin Ogbu、Jonathan Lusseau、Gülbin Kurtay、Frédéric Robert、Yannick Landais
DOI:10.1039/d0cc05069e
日期:——
Urethanesynthesis via oxidative decarboxylation of oxamic acids under mild electrochemical conditions is reported. This simple phosgene-free route to urethanes involves an in situ generation of isocyanates by anodic oxidation of oxamic acids in an alcoholic medium. The reaction is applicable to a wide range of oxamic acids, including chiral ones, and alcohols furnishing the desired urethanes in a