Ultrasound-assisted synthesis of eight novel and highly functionalized 2-aminonitrile oxazoles via Ugi-3CR

Eight novel 2-aminonitrile oxazoles were synthesized efficiently and quickly via the Ugi reaction in its three-component version in moderate to good yields (55-82%) at room temperature or in good to excellent yields (70-96%) using ultrasound irradiation (USI) as heat source. It is noteworthy that not only the yields were improved by using USI, also the reaction times decreased considerably, from 6-10 hours (at r.t.) to 1-2 hours (USI), depending on the substituents. The final products are highly functionalized molecules because they contain an amino group, a nitrile group, an oxazole group and a very reactive biaryl-benzylic position. In this context, they can be used for further condensations, cyclizations and/or functionalizations toward a variety of compounds with potential applications in several fields of knowledge like optics, material science and medicinal chemistry. All products were fully characterized by spectroscopic techniques (H and C-NMR, IR and HRMS), even by mp and Rf.