Boronate Urea Activation of Nitrocyclopropane Carboxylates
摘要:
Boronate ureas operate as catalysts for the activation of nitrocyclopropane carboxylates in nucleophilic ring-opening reactions. A variety of amines were found to open the urea-activated nitrocyclopropane carboxylates, generating highly useful nitro ester building blocks In good yields. Standard manipulations allow access to a wide range of valuable compounds from the ring-opened products with direct applications in bioactive target synthesis.
Internal Lewis acid assisted ureas: tunable hydrogen bond donor catalysts
作者:David M. Nickerson、Veronica V. Angeles、Tyler J. Auvil、Sonia S. So、Anita E. Mattson
DOI:10.1039/c2cc37073e
日期:——
The strategic incorporation of internal Lewis acids onto urea scaffolds gives rise to a family of tunable hydrogenbond donor catalysts. The nature of the Lewis acid and associated ligands affects the urea polarization, acidity, and activity in reactions of nitrocyclopropane carboxylates and nitrodiazoesters.
Internal Lewis Acid Assisted Hydrogen Bond Donor Catalysis
作者:Sonia S. So、Julie A. Burkett、Anita E. Mattson
DOI:10.1021/ol102899y
日期:2011.2.18
Boronate ureas are introduced as a new class of noncovalent catalysts for conjugate addition reactions with enhanced activity. Through intramolecular coordination of the urea functionality to a strategically placed Lewis acid, rate enhancements up to 10 times that of more conventional urea catalysts are observed. The tunable nature of boronate ureas is a particularly attractive feature and enables the rational design of catalysts for optimal performance, in terms of both activity and stereocontrol, in new bond-forming processes.