518976-74-4Relevant academic research and scientific papers
Alkyl Isocyanates via Manganese-Catalyzed C-H Activation for the Preparation of Substituted Ureas
Huang, Xiongyi,Zhuang, Thompson,Kates, Patrick A.,Gao, Hongxin,Chen, Xinyi,Groves, John T.
supporting information, p. 15407 - 15413 (2017/11/06)
Organic isocyanates are versatile intermediates that provide access to a wide range of functionalities. In this work, we have developed the first synthetic method for preparing aliphatic isocyanates via direct C-H activation. This method proceeds efficiently at room temperature and can be applied to functionalize secondary, tertiary, and benzylic C-H bonds with good yields and functional group compatibility. Moreover, the isocyanate products can be readily converted to substituted ureas without isolation, demonstrating the synthetic potential of the method. To study the reaction mechanism, we have synthesized and characterized a rare MnIV-NCO intermediate and demonstrated its ability to transfer the isocyanate moiety to alkyl radicals. Using EPR spectroscopy, we have directly observed a MnIV intermediate under catalytic conditions. Isocyanation of celestolide with a chiral manganese salen catalyst followed by trapping with aniline afforded the urea product in 51% enantiomeric excess. This represents the only example of an asymmetric synthesis of an organic urea via C-H activation. When combined with our DFT calculations, these results clearly demonstrate that the C-NCO bond was formed through capture of a substrate radical by a MnIV-NCO intermediate.
Orally Active β-Lactam Inhibitors of Leukocyte Elastase-1. Activity of 3,3-Diethyl-2-azetidinones
Shah, Shrenik K.,Dorn, Conrad P.,Finke, Paul E.,Hale, Jeffrey J.,Hagmann, William K.,et al.
, p. 3745 - 3754 (2007/10/02)
A thorough analysis of the mechanism of inhibition of human leukocyte elastase (HLE) by a monocyclic β-lactam and the mechanism of β-lactam hydrolysis led to the preparation of potent and highly stable inhibitors of HLE.This work led to the identification of 4--3,3-diethyl-1-carbonyl>-2-azetidinone (2) as the first orally active inhibitor of human leukocyte elastase (HLE).Analogs of 2 with different substituents on the urea N were synthesized and evaluated for their activity in vitro against HLE as well as in vivo in a hamster lung hemorrhage model.Compounds with a methyl or a methoxy group in the para position of the benzene ring were very potent in both assays.The results are discussed on the basis of the proposed model for the binding of this class of inhibitors to HLE and a possible mechanism of inhibition is presented.
