Dual Activation of Unsaturated Amides with Schwartz's Reagent: A Diastereoselective Access to Cyclopentanols and N,O‐Dimethylcyclopentylhydroxylamines.
The concomitant generation of a nucleophilic and an electrophilic site from unsaturated Weinreb amide by using Cp2Zr(H)Cl) as the unique reagent was developed to promote a cyclisation reaction. The access to trans-2-substituted cyclopentanols or cyclopentylhydroxylamines can be selectively driven by a judicious choice of the cyclisationpromotor. An access to cis-3-substituted is also described.
A highly diastereoselective synthesis of trans-2-substituted cyclopentylamines via a tandem hydrozirconation/Lewis acid-mediated cyclization sequence applied to butenyl oxazolidines is described. The method allows an easy preparation of diversely substituted cyclopentylamines which appear to be useful synthetic intermediates. This was further illustrated by the syntheses of (±)-Rodocaine, (±)-trans-pentacin