Studies on Instructive Construction of <i>exo</i>-Olefin Terminated Five- and Six-Membered Nitrogen Heterocycles: SmI<sub>2</sub>-Mediated Intramolecular Cyclization of Haloalkynals
pyrrolidine and piperidine frameworks was developed by employing SmI2-mediated intramolecular radical cyclization of haloalkynaks. The radical cyclization affording 2,3-disubstituted pyrrolidines and piperidines proceeded in a highly stereoselective manner. However, decreasing stereoselectivety was observed in the preparation of 2,4-disubstituted pyrrolidine and 3,4-disubstituted piperidinederivatives in the
The photochemically initiated dehydro-Diels-Alder (PDDA) reaction is an efficient and versatile method for the prepa- ration of biaryls. The ring closure may take place both inter- and in- tramolecularly, of which the intramolecular variant is more productive from the preparative point of view. A variety of linkers can be employed to connect the ynone moiety, which acts as the chromophore, with another
A Modular Approach for the Synthesis of Dibenzoazepine Derivatives
作者:Gerhard Hilt、Fabrizio Galbiati、Klaus Harms
DOI:10.1055/s-2006-942511
日期:2006.11
A straightforward reaction sequence consisting of a Sonogashira coupling of protected propargylic amines, a cobalt-catalysed neutral Diels-Alder reaction, DDQ oxidation of the dihydroaromatic intermediate, a sodium borohydride reduction and an acid induced Friedel-Crafts-type cyclisation approach incorporating four simple starting materials leads to polyfunctionalised polycyclic products. Based on the electronic, steric and structural preconditions either seven-membered dibenzoazepine derivatives or alternatively six- or eight-membered isoindoline derivatives are formed.