e.g. Filippa Pettersson or Cancer Res. 75(6) , 1102-12, (2015) or 10.1002/anie.201600521
Allylidenetriphenylphosphorane as a bifunctional reagent: synthesis of cyclopentenones and. alpha.,. beta.-unsaturated ketones with [3-(alkoxycarbonyl)-2-ethoxy-2- …
When (3-(ethoxycarbonyl)-2-ethoxy-2-propenylidene) triphenylphosphorane (6) was allowed to react with a-bromo ketones 8a-d in dichloromethane in the presence of Cs2CO3 at room temperature, a [3+ 21 annulation occurred and led to the formation of the corresponding 2-ethoxycyclopentadienes Sa-d in excellent yields. Similarly, bromo thioester 8g underwent the annulation to give 44ethylthio)-cyclopentadiene Sg. Secondary ...