First General Approach to Cyclohex-3-ene-1,1-bis(phosphonates) by Diels−Alder Cycloaddition of Tetraethyl Vinylidenebis(phosphonate) to 1,3-Dienes

• Published in: Journal of organic chemistry Vol. 68; no. 3; pp. 736 - 742
• Main Authors: Ruzziconi, Renzo, Ricci, Giacomo, Gioiello, Antimo, Couthon-Gourvès, Hélène, Gourvès, Jean-Philippe
• Format: Journal Article
• Language: English
• Published: WASHINGTON American Chemical Society 07.02.2003; Amer Chemical Soc
• Subjects: Alicyclic compounds; Alicyclic compounds, terpenoids, prostaglandins, steroids; Chemistry; Chemistry, Organic; Exact sciences and technology; Organic chemistry; Physical Sciences; Preparations and properties; Science & Technology; REACTIVITY; BISPHOSPHONATES; ESTERS; Cyclohexane derivatives; Diels Alder addition; Electronic effect; Organic phosphonate; Dienic compound; Chemical synthesis; Ethylenic compound
• ISSN: 0022-3263; 1520-6904
• DOI: 10.1021/jo0205154

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.