188. Palladium-catalyzed intramolecular zinc-ene reactions
     Oppolzer, W.; Schröder, F.
     Tetrahedron Lett. 1994, 35, 7939-7942

Cyclizations of acetoxydienes 1 with Pd(PPh₃)₄/Et₂Zn (0.05/4–5 mol-equiv.) in Et₂O at reflux, followed by either protonation, iodination or cyanation, provide cis-disubstituted cyclopentanes and pyrrolidines 5, 7 or 9. These tandem reactions, as well as the conversions 5 → 17 or 18 and 20 → 22 show good to excellent regio- and stereocontrol, which is compared to those of Pd-ene ring closures of 1 and 20.

DOI : 10.1016/0040-4039(94)80016-2 

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