19311-91-2Relevant articles and documents
Chemo- and Regioselective Anionic Fries Rearrangement Promoted by Lithium Amides under Aerobic Conditions in Sustainable Reaction Media
Antenucci, Achille,Blangetti, Marco,Bolzoni, Paola,De Nardi, Federica,Ghinato, Simone,Prandi, Cristina
, (2022/05/27)
A straightforward and efficient protocol to promote the metalation/anionic Fries rearrangements of O-aryl carbamates, using for the first time a lithium amide as metalating agent under aerobic/ambient-friendly reaction conditions, is reported. This approach enables the sustainable preparation of salicylamide derivatives with high levels of chemoselectivity within ultrafast reaction times, working at room temperature in the presence of air/moisture, and using environmentally responsible cyclopentyl methyl ether as a solvent. Furthermore, the regioselective manipulation of O-2-tolyl carbamates has been accomplished using interchangeably alkyllithiums or lithium amides, with an unexpected beneficial contribution from the employment of biorenewable protic eutectic mixtures as non-innocent reaction media.
Aryl Carbamates: Mechanisms of Orthosodiations and Snieckus-Fries Rearrangements
Ma, Yun,Woltornist, Ryan A.,Algera, Russell F.,Collum, David B.
, p. 9051 - 9057 (2019/08/15)
Aryl carbamates are orthometalated by sodium diisopropylamide (NaDA) in tetrahydrofuran. The resulting arylsodiums undergo Snieckus-Fries rearrangement to give orthoacylated phenols in good yield. The intermediate arylsodiums and resulting orthoacylated phenolates are suggested to be monomeric. The rate-limiting step in the two-step sequence depends on the steric demands of the carbamoyl moiety and the substituents in the meta position of the arene. Rate studies reveal a dominant disolvated-monomer-based orthometalation followed by a di- or trisolvated arylsodium monomer-based rearrangement. Kinetic evidence of a NaDA-catalyzed Snieckus-Fries rearrangement suggests the intermediacy of mixed trimers. Competitive halide eliminations to form benzyne are also discussed.
Submillisecond organic synthesis: Outpacing Fries rearrangement through microfluidic rapid mixing
Kim, Heejin,Min, Kyoung-Ik,Inoue, Keita,Im, Do Jin,Kim, Dong-Pyo,Yoshida, Jun-Ichi
, p. 691 - 694 (2016/05/19)
In chemical synthesis, rapid intramolecular rearrangements often foil attempts at site-selective bimolecular functionalization.We developed a microfluidic technique that outpaces the very rapid anionic Fries rearrangement to chemoselectively functionalize iodophenyl carbamates at the ortho position. Central to the technique is a chip microreactor of our design, which can deliver a reaction time in the submillisecond range even at cryogenic temperatures.The microreactorwas applied to the synthesis of afesal, a bioactive molecule exhibiting anthelmintic activity, to demonstrate its potential for practical synthesis and production.
