Fused Dihydrodibenzobarrelene (Dibenzobicylco[2.2.2]octadiene) and Lactone Rings via Tandem Diels‐Alder and Condensation Reactions of Dialkyl Fumarates and 9‐Anthracenemethanol

Abstract

A series of fused dihydrodibenzobarrelene (dibenzobicyclo[2.2.2]octadiene) and lactone rings were prepared from dialkyl fumarates and 9‐anthracenemethanol. These products were prepared via a one‐pot synthesis in which a Diels‐Alder reaction occurred followed by an intramolecular transesterification to form the lactone ring. A key feature of this synthetic methodology is the straightforward purification of the reaction products, in most cases without the need for chromatography. The ease of work‐up along with the simple setup of the reaction (no catalysts or other reagents needed) make this methodology a convenient and potentially scalable route to complex, multicyclic structures. Molecular modeling of the transition structures for Diels‐Alder reaction suggested that transesterification could precede cycloaddition, but NMR in situ studies confirmed the opposite occurrence. Product formed exclusively in the trans configuration for all alkyl fumarates used.

Small-Molecule Investigation of Diels–Alder Complexes for Thermoreversible Crosslinking in Polymeric Applications

“…This reaction is discussed and analyzed in a different publication and thus was excluded from further investigation as it was no longer possible to reform the starting diene and dienophile. 32 The eight complexes that underwent further investigation are shown in Figure 3. For the compounds V and VII, two different possible isomers formed, which was observed to occur in a 50:50 mixture between the isomers (see the Supporting Information for NMR); however, for V, separation of the isomers was possible via column chromatography to produce V exo and V endo .…”

“…It was found during the investigation that the ninth combination ( IX ) underwent a further intramolecular reaction to form a dihydrobenzobarrelene and fused lactone ring structure (Figure ). This reaction is discussed and analyzed in a different publication and thus was excluded from further investigation as it was no longer possible to reform the starting diene and dienophile …”

“…Figure2. Structure and reaction of the combination of reactants 3 and E to form a dihydrobenzobarrelene and fused lactone ring structure, compound IX 32. …”