Reaktionen cyclischer Oxalylverbindungen, 35. Untersuchung von Reaktionsmechanismen durch Isotopenmarkierung, 11. Zur Umsetzung von 4‐Benzoyl‐5‐phenylfuran‐2,3‐dion mit S‐Heterocumulenen — Präparative und mechanistische Aspekte

Abstract

Reactions of Cyclic Oxalyl Compounds, 35 [1] . — Mechanistic Investigation Aided by Isotopic Labeling, 11 [2] . — On the Reaction of 4‐Benzoyl‐5‐phenylfuran‐2,3‐dione with S‐Heterocumulenes — Preparative and Mechanistic Aspects [3] The furan‐2,3‐dione 1 combines with N ‐sulfinylamines or sulfur diimides to afford the pyrrole‐2,3‐diones 2 , while with N ‐tosylsulfinylamine the (α‐iminobenzyl)furandione 3 is obtained. (α‐Iminobenzyl)pyrrolediones 4 are formed in the reaction of 2c with N ‐tosylsulfinylamine or from 3 with N ‐tosylsulfur diimides. Diisopropylcarbodiimide and the pyrroledione 2c or the (iminobenzyl)furandione 3a undergo [4 + 2] cycloaddition reactions accompanied by novel and surprising rearrangements to furnish the bicyclic compounds 5 and 6 , respectively. The molecular skeleton of 6 was confirmed by an X‐ray diffraction analysis. With the aid of 17 O‐labeling experiments and 17 O‐NMR spectroscopy mechanistic pathways including novel rearrangements were made evident.