A new efficient synthesis of 3-methylene 2-pyrrolidinone 1 ylide-lactame 6 is reported. Diels- Alder cycloadditions of 1 to cyclopentadiene exhibited very high exoselectivities, regardless of the experimental conditions. These results confirm the generality of exoselectivity for conformationally restricted s-cis dienophiles and indicate that the dienophile functionality and dipole moment have little influence on its magnitude.
[Klutchko, Sylvester; Hoefle, Milton L.; Smith, Ronald D.; Essenburg, Arnold D.; Parker, Robert B.; et al. Journal of Medicinal Chemistry, 1981 , vol. 24, # 1 p. 104 - 109]
[Klutchko, Sylvester; Hoefle, Milton L.; Smith, Ronald D.; Essenburg, Arnold D.; Parker, Robert B.; et al. Journal of Medicinal Chemistry, 1981 , vol. 24, # 1 p. 104 - 109]
