Synthesis of Penta-2,4-dienenitriles by the Horner–Wadsworth–Emmons Olefination of EnonesThe authors are grateful for financial support from the Fundação de Amparo à Pesquisa do Estado do Rio Grande do Sul (FAPERGS/CNPq – PRONEX – Grant No. 16/2551-0000477-3) and fellowships from CNPq (C.E.B., C.A.F.), CAPES (M.A.M.), and FAPERGS (A.F.C.).
Received: 14 June 2017
Accepted after revision: 18 July 2017
24 August 2017 (eFirst)
Three new series of compounds, 5-alkoxy-3-(trifluoromethyl)penta-2,4-dienenitriles, 5-(phenylthio)-3-(trifluoromethyl)penta-2,4-dienenitriles, and ethyl 4-alkoxy-2-(cyanomethylene)but-3-enoates, obtained from the olefination reaction of the respective enones with diethyl cyanomethylphosphonate via the Horner–Wadsworth–Emmons olefination are reported. All products were obtained as single regioisomers; however, the composition of the stereoisomers changed according to the enone substituents. A study based on 1H and 13C NMR chemical shifts, 1H–19F and 13C–19F NMR coupling constants, 1H NMR signal integrals, and HSQC, HMBC, and NOESY experiments was performed in order to assign the structure and percentage of each stereoisomer obtained.