A Proton-Catalyzed Dimerization of a 2-Amino-1,3-diene which Ultimately Yields a 3-Aminobicyclo[4.2.0]octa-2,4-diene

Gerhard Maas, Rainer Rahm
2005 Zeitschrift für Naturforschung. B, A journal of chemical sciences  
The 2-pyrrolidino-1,3-dienes (E)-5 and (Z)-5 are obtained by the reaction of lithium di(tertbutyl) cuprate with propyne iminium salt 3. Quantitative Z→E isomerization of 5 takes place within 4 hours at 20 °C. In benzene solution, (E)-5 slowly equilibrates with a [1,5]-H shift to form the 1-amino-1,3-diene derivative 6. In concentrated chloroform solution, however, (E)-5 is transformed into the 3-pyrrolidino-bicyclo[4.2.0]octa-2,4-diene 7 which is identified by X-ray crystal structure analysis.
more » ... tructure analysis. A mechanism for this transformation is proposed.
doi:10.1515/znb-2005-0611 fatcat:x6qsgiz3bvbb5eussqhslgnxmm