Intramolecular carbenoid addition to 1,3-dienes. Synthesis of cyclopentene annulated ring systems.

✍ Scribed by T. Hudlicky; J.P. Sheth; V. Gee; D. Barnvos

• Book ID: 104238076
• Publisher: Elsevier Science
• Year: 1979
• Tongue: French
• Weight: 342 KB
• Volume: 20
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(01)86741-1

✦ Synopsis

Diazoketones containing a 1,3-diene moiety were decomposed to yield corresponding vinylcyclopropanes stereospecifically. Transformation of vinylcyclopropanes to cyclopentenes is described and the scope of the reaction is discussed. The intramolecular addition of carbenoids to conjugated dienes has not been significantly exploited in organic synthesis relative to the well documented intramolecular ring closures of olefinic diazoketones.' Many applications of the latter methodology can be found in the context of natural product synthesis.* Recent examples of the intramolecular addition of carbenoids to 1,3-dienes3 portend well to the general utility of the reaction as such additions can lead to the regiospecific and stereospecific formation of quaternary centers with concomitant closure of one or more rings (Scheme I). Scheme I Furthermore, the initially formed 1,2-adducts can be transformed into cyclepentenes under a variety of conditions ranging from photolysis4 or flash pyrolysis4'5 to a subtle transition metal catalyzed bond reorganization,6 thus represanting a formal 1,4-addition of a carbenoid to a diene. The possibility of using such a