An asymmetric, phase-transfer-catalyzed vinylogous conjugate addition–vinylogous cyclization cascade of olefinic azlactones with 4-nitro-5-styrylisoxazoles is reported. In the presence of an l-tert-leucine-derived urea–quaternary ammonium salt as a bifunctional phase-transfer catalyst and KF, two series of valuable optically pure cyclohexenones featuring two and three stereocenters were obtained in
An efficient and concise method to synthesize locked GFP chromophore analogues
作者:Soumit Chatterjee、Peter Karuso
DOI:10.1016/j.tetlet.2016.10.021
日期:2016.11
A series of GFP analogues, which are fluorescent in the solid state at room temperature, but weakly fluorescent in solution, have been synthesized via an oxazolone formation process that involves a condensation reaction in the presence of a Lewis acid following a Knoevenagel condensation. A ring opened intermediate is formed which cyclizes readily upon heating to produce the imidazolinone. This method