66309-77-1Relevant academic research and scientific papers
REGIOSELECTIVITY IN THE DIELS-ALDER REACTIONS OF α-PYRONES WITH ALKYNES
Dieter, Karl R.,Balke, Wiliam H.,Fishpaugh, Jeffrey R.
, p. 1915 - 1924 (2007/10/02)
4-Ethyl-5-methyl-6-methylthio-2(H)-pyranone (4) undergoes Diel-Alder reactions with ethyl hexynoate (5), 3-heptyn-2-one (6), ethyl propiolate (7), and 3-butyn-2-one (8) to afford substitutes benzenes with high regioselectivity upon extrusion of CO2. 4-Ethyl-5,6-dimethyl- (1), 4-ethyl-3,6-dimethyl- (2) and 4-ethyl-5-methyl-(2H)-pyranone (3) gave excellent to good regioselectivity with internal alkynes 5 and 6 and poor regioselectivity with terminal alkynes 7 and 8.MNDO calculations have been carried out on the pyrones and alkynes and qualitative FMO analysis correctly predicts the major products.
