The investigation of an intramolecular Diels-Alder reaction, en route to a projected total synthesis of maoecrystal V, is described. (C) 2009 Elsevier Ltd All rights reserved.
Palladium-mediated domino oxidative amination of cyclohexadienes as an entry to indole alkaloids
reaction on cyclohexa-2,5-dienes has been developed, leading to the tetracyclic indoline skeleton of aspidosperma and strychnos alkaloids. The allyl-palladium intermediate, generated after the double oxidative amination, could be trapped by an internal nucleophile to allow the construction of 3 rings in a single step. Approaches to the synthesis of strychnine and mossambine is finally reported.
electron-deficient olefins gave substituted hydrocarbazoles in up to 99% yield and 94% ee. This reaction was catalyzed by a novel chiral holmium(III) complex. Alkylation of the cycloadduct gave a tricyclic compound with four continuous chiral centers, one of which was a quaternarycarbon.