TANDEM OXIDATION/CYCLIZATION REACTION OF 4-(ARYLMETHYL)OXY-2-DIAZOBUTYRATE DERIVATIVES

摘要

A tandem oxidation/cyclization reaction of gamma-(arylmethyl)oxy-alpha-diazobutyrate derivatives was investigated. While oxidative cleavage of the PMB ether was only observed upon treatment of an alpha-diazo-beta-ketoester with DDQ, oxidation of alpha-diazo esters with an sp(3) carbon at the beta-position was accompanied by intramolecular attack of the diazo carbon atom and expulsion of the nitrogen gas to give 2,3-dihydrofurans in modest to good yields when an electron-withdrawing group was substituted at the beta-position. Substrates bearing no electron-withdrawing beta-substituent were found to give rearranged products, albeit in modest yields. A benzofuran derivative could also be obtained, although a hydroquinone adduct was formed as a byproduct.