First General Approach to Cyclohex-3-ene-1,1-bis(phosphonates) by Diels−Alder Cycloaddition of Tetraethyl Vinylidenebis(phosphonate) to 1,3-Dienes Renzo Ruzziconi Giacomo Ricci Antimo Gioiello Hélène Couthon-Gourvès Jean-Philippe Gourvès 10.1021/jo0205154.s002 https://acs.figshare.com/articles/journal_contribution/First_General_Approach_to_Cyclohex-3-ene-1_1-bis_phosphonates_by_Diels_Alder_Cycloaddition_of_Tetraethyl_Vinylidenebis_phosphonate_to_1_3-Dienes/3694023 Tetraethyl vinylidenebis(phosphonate) (VBP) reacts smoothly with substituted 1,3-dienes at 90−110 °C without solvent to give the corresponding cyclohex-3-ene-1,1-bis(phosphonates) in good yields (60−85%). With nonsymmetrically substituted dienes, mixtures of regioisomers are obtained, the regioisomeric ratio being exclusively controlled by electronic effects. Danishefsky's diene allows tetraethyl 4-oxocyclohex-2-ene-1,1-bis(phosphonate) to be obtained in an 81% overall yield after the acid-catalyzed hydrolysis of the Diels−Alder cycloadduct. With 2,3-dimethoxy-1,3-butadiene, a mixture of regioisomeric dimethoxycyclohexene-1,1-bis(phosphonates) is formed by the VBP-catalyzed isomerization of the normal Diels−Alder cycloadduct. The mixture converges into tetraethyl 3,4-dimethoxycyclohex-2-ene-1,1-bis(phosphonate) at prolonged reaction times. 2003-01-07 00:00:00 diene VBP tetraethyl cycloadduct Diel Tetraethyl reaction times First General Approach mixture converges regioisomeric ratio