- Intramolecular Diels-Alder reaction of cyclenic trienes: Stereoselectivity and NMR structure determination
-
A series of trienes possessing an internally cyclenic dienophilic group undergo thermal intramolecular DielsAlder (IMDA) reaction with high selectivity for the cis-fused products. A concentrated solution of LIC1O4 in diethyl ether catalyzes the IMDA reaction of cyclenic nitrotrienes, giving rise to the irans-fused compounds. The stereochcmical outcome of these various processes are rationalized in terms of a minimization of the steric interactions between the ring and the chain on the one hand and the endo-stabilization from the nitro group on the other. The structures of the cycloadducts have been carefully determined by NMR 1H and 13C spectroscopy: dipolar interactions, detected via nuclear Overhauser effects, and criteria based on scalar coupling and moreover on chemical shifts have been employed. Conformational preferences were observed. Elsevier,.
- Blond, Alain,Platzer, Nicole,Guy, Alain,Dhotel, Helene,Serva, Laurence
-
p. 283 - 293
(2007/10/03)
-
- Nickel- and Palladium-Catalyzed Additions of Nucleophiles to Cyclic 1,3-Dienes
-
Carbon nucleophiles have been found to add smoothly to 1,3-cyclohexadiene using either a preformed nickel-ligand complex or Ni(0) prepared by in situ reduction of Ni(II) in the presence of a ligand to give 1,2- and 1,4-addition products.Analogous adducts were also obtained from 1,3-cyclopentadiene and 1,3-cyclooctadiene, but the yields were considerably lower.Attempts to add benzenesufinic acid to 1,3-cyclohexadiene using Ni(0) were unsuccessful; this reaction was instead found to be catalyzed by Pd(0)-phosphite complexes.
- Andell, Ove S.,Baeckvall, Jan-E.,Moberg, Christina
-
p. 184 - 189
(2007/10/02)
-