Synthesis of Tricyclic Nitrogen Compounds via a Tandem Cyclization-Cycloaddition-Cationic Cyclization Sequence
作者:Joseph P. Marino、Martin H. Osterhout、Alan T. Price、Mark A. Semones、Albert Padwa
DOI:10.1021/jo00098a004
日期:1994.9
The intramolecular cycloaddition of isomunchnone dipoles containing alkenyl pi-bonds produces oxabicyclic amides. These cycloadducts were employed as masked N-acyliminium ions for cationic pi-cyclizations as an approach to B-ring homologues of erythrinane alkaloids.
Tandem Dipolar Cycloaddition−Mannich Cyclization as an Approach to Tricyclic Nitrogen Heterocycles
作者:Albert Padwa、Michael A. Brodney、Joseph P. Marino、Martin H. Osterhout、Alan T. Price
DOI:10.1021/jo9607267
日期:1997.1.1
stereochemistry of the resulting A/B ring fusion is analogous to similar erythrinane products obtained via a Mondon-enamide-type cyclization. The stereochemical assignment of the final cyclized products was determined by X-ray crystallography. Molecularmechanicscalculations show that the ground state energy of the cis-fused diastereomer is 4.6 kcal lower than that of the trans diastereomer, and presumably some