Oxidation Strategy for the Synthesis of Regioisomeric Spiroisobenzofuranopyrroles: Facile Entries to Spiro[isobenzofuran-1,2 '-pyrrole] and Spiro[isobenzofuran-1,3 '-pyrrole] Derivatives

摘要

Two practical and efficient approaches have been developed to sythesize two kinds of racemic spiroisobenzofuranopyrrole analogues as regioisomers, In the presence of Sodium periodate, as-indeno[1,2-b]pyrrol-4(1H)-ones were converted into spiro[isobenzofuran-12'-pyrrole] derivatives by a two-step process. In addition, oxidative reactions promoted by lead tetraacetate were demonstrated using cis-indeno[2,1-6]pyrrol-8(1H)-ones as substrates, affording spiro[isobenzofuran-1,3'-pyrrole] derivatives. The remarkable features of two approaches included mild and convenient reaction conditions, a broad substrate scope and moderate to excellent yields. Possible mechanisms were proposed based on the comparison of the intermediates and products