Regioselective conversion of alkynes to 4-substituted and 3,4-disubstituted isoxazoles using titanium-catalyzed multicomponent coupling reactions
作者:Amila A. Dissanayake、Aaron L. Odom
DOI:10.1016/j.tet.2011.11.043
日期:2012.1
Conditions have been developed for the regioselective synthesis of 4-substituted isoxazoles from terminal alkynes and 3,4-disubstituted isoxazoles from internal alkynes. The methodology involves a one-pot titanium-catalyzedmulticomponentcouplingreaction followed by simple hydroxylamine hydrochloride addition.
Triaryl-2-pyridylidene effectively facilitates the gold-catalyzedoxidative C-H arylation of heteroarenes with arylsilanes as a unique electron-donating ligand on gold. The employment of the 2-pyridylidene ligand, which is one of the strongest electron-donating N-heterocyclic carbenes, resulted in the rate acceleration of the C-H arylation reaction of heterocycles over conventional ligands such as
Molybdenum-Mediated One-Pot Synthesis of 2-Hydroxypyrimidines from Isoxazoles
作者:Stéphane Beaumont、Servane Rochelle
DOI:10.1055/a-2107-4492
日期:2023.11
A one-pot procedure towards substituted 2-hydroxypyrimidines from commercially available isoxazoles is reported. The process involves cleavage of the isoxazole N–O bond mediated by Mo2(OAc)4, then in situ hydrolysis of the resulting β-aminoenone to the reactive 1,3-dicarbonylated intermediate, followed by hydroxypyrimidine formation in the presence of urea. Moderate to excellent yields are obtained
报道了从市售异恶唑中制备取代的 2-羟基嘧啶的一锅法。该过程涉及由 Mo 2 (OAc) 4介导的异恶唑 N-O 键断裂,然后将所得 β-氨基烯酮原位水解为反应性 1,3-二羰基化中间体,然后在尿素存在下形成羟基嘧啶。获得中等至优异的产率,产生官能化的羟基嘧啶。通过使用容易获得的异恶唑,可以通过该方法制备多种新的多样化的多取代羟基嘧啶。