Inversion of configuration in a fused cyclopropane ring opening by hydrochloric acid

✍ Scribed by H. Hogeveen; C.F. Roobeek; H.C. Volger

• Publisher: Elsevier Science
• Year: 1972
• Tongue: French
• Weight: 243 KB
• Volume: 13
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(01)84285-4

✦ Synopsis

Opening of a cyclopropane ring by electrophiles can in principle occur via an inversion or via a retention mechanism. It has been found that with the proton as electrophile the opening proceeds with retention of configuration in the case of With halogen as electrophilic agent both inversion* and on the substrate. bicyclobutanes' end cyclopropanols*. retention' have been observed, depending We wish to report an example of electrophilic addition of &drogen chloride to a Eyclopropane ring occurring via inversion of configuration at the carbon atom attacked initially*. Introduction of gaseous hydrogen chloride in a lo-204% solution of 1,2.3,4,5,6-hexametbyl-exo-tricycle [4.1.0.0*'5]hept-3-ene41=in CH2C120r CHC13 at room temperature gives immsdiately a quantitative conversion to 1,2,3,4,5-m-,7-z-hexamethyl, 7-anti-chlorobicycld2.2.l~hept-* A few other examples of "end-on" protonation of a cyclopropene ring have recently been published3.