Ketene-S,S,-acetals—VI

Add time:07/21/2019    Source:sciencedirect.com

The α-ketoketene-S,S,-acetals 2a–h have been synthesized from the appropriate ketones 1a–f in good yields by extending the established method. The acetals 2a–d react with guanidine in the presence of sodium ethoxide to give pyrimidines 4a–d in 35–59% overall yields (Scheme 1). Treatment of 2e with guanidine similarly gave 5a in 23% yield. However, the reaction of 2e with guanidine in the presence of sodium n-propoxide gave a mixture of three products from which 5a was isolated as major product (20%) with 6a (7%) and 7a (5%). Under similar reaction conditions, 2f gave 5b, 6b and 7b in identical yields. Treatment of 2g–h with guanidine in the presence of sodium n-propoxide gave only 8a (28%) and 8b (23%) respectively. The formation of these pyrimidines involves base induced 1,3-proton migration in 2a–h to give intermediate olefins 10a–h.

We also recommend Trading Suppliers and Manufacturers of 1-Propene, 1-(methylthio)- (cas 10152-77-9). Pls Click Website Link as below: cas 10152-77-9 suppliers

Prev:Synthesis and reactivity of new methylallylpalladium(II) complexes with bidentate 2-(methylthio-N-benzylidene)anilines
Next:Infrared, Raman and NMR spectra, conformational stability, normal coordinate analysis and B3LYP calculations of 5-amino-4-cyano-3-(methylthio)-1H-pyrazole-1-carbothioamide)