Electrochemically induced Hofmannrearrangement under new solvent systems containing a variety of alcohols was developed. Since the reaction proceeds under mild conditions (neutral), a variety of carbamates possessing various alkoxy moieties could be easily prepared by this method. An epoxy functional group in the amide and alcohol parts remained intact during the electrolysis.
investigated. Aniline was reacted with titanium n‐butoxide (1) in the presence of carbon dioxide (5 MPa) to give the corresponding n‐butyl N‐phenylcarbamate (BPC) in nearly quantitative yield (99 %) within 20 min. Furthermore, 1 could be regenerated upon reaction with n‐butanol during water removal. The recovered 1 could then be reused in a subsequent reaction.
研究了在Ti(OR)4(R = n Bu(1),Me(2),Et(3),n Pr(4))存在下从胺和二氧化碳直接合成氨基甲酸酯的方法。在二氧化碳(5 MPa)存在下,苯胺与正丁醇钛(1)反应,在20分钟内以几乎定量的产率(99%)得到相应的正丁基N-苯基氨基甲酸酯(BPC)。此外,在脱水过程中与正丁醇反应后可再生1。恢复的1 然后可以在后续反应中重复使用。
Base-Catalyzed Transcarbamoylation
作者:Vincent Semetey、Benoît Rhoné
DOI:10.1055/s-0036-1588866
日期:2017.9
Inorganic bases such as NaH, KOt-Bu, NaOH, or KOH are efficient catalysts to promote the transcarbamoylation reaction between urethanes and a variety of primary and secondary alcohols under mild conditions. They constitute an alternative to organometallic catalysis and can be applied to aliphatic or aromatic urethanes.
various amounts of amines. Bromine was superior to chlorine as a halogen source for the formation of carbamates. unexpectedly, the addition of HgCl2 resulted in a decrease in the carbamate yield. When N-halosuccinimides were used in the place of halogens, an additional formation of the succinimide-incorporated product was observed to some extent.
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