The stereochemistry of diels-alder reactions of cyclopropenes

✍ Scribed by Yitzhak Apeloig; Dorit Arad; Moshe Kapon; Mercedes Wallerstein

• Publisher: Elsevier Science
• Year: 1987
• Tongue: French
• Weight: 302 KB
• Volume: 28
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(01)81090-x

✦ Synopsis

The stereochemistry of the Diels-Alder reactions of 3 cyclopropenes was determined unequivocally by X-ray and NOE studies. Tetrachlorocyclopropene yields exo-adducts with (r)-l-R-1,3-butadiene (R=OCH3, OCOCH3, OSiMe ), with 1,4_diphenylbutadieKand with furan. 1,2-bromochlorocyclopropene yields with (E)-?-R-butadienes (R=OCH3, OSiMe ) endo:exo-adducts in a ratio of 9:l. Cyclopropene + 1-methoxyFutadiene yield only the endo-ad -2 uct. The Uiels-Alder (DA) reaction is the most important method for formation of six-membered rings and it has been extensively studied.* Recently, special attention has been devoted to the study of the stereochemistry and the mechanism of this reaction.2b*c