Oxa bowls: Studies toward hexaoxa-[6]-peristylane. Synthesis of a seco-derivative of hexaoxa-[6]-peristylane

When the concept of equivalency of all-cis-[n]-formyl-[n]-cycloalkanes with [n]-oxa-[n]-peristylanes was followed, an approach to the "oxa bowl" hexao xa-[6]-peristylane 4a was delineated. This required an access to all-cis-cy clohexane-hexacarbaldehyde 5, which could be subjected to a 6-fold intramol ecular acetalization cascade. A readily available Diels-Alder adduct of cyc looctatetraene and maleic anhydride was chosen as the starting material and was elaborated to the endo, endo-tetraene 6 in which all the six aldehyde functionalities are present in a latent form with cis orientation in a lock ed cyclohexane ring. Although ozonolysis of 6 has so far led only to intrac table products, the novelty and brevity of our approach have been demonstra ted through the intramolecular acetalizations through ozonolysis in 7 and 1 5, leading to oxa bowls 9 (seco-hexaoxaperistylane) and 16, respectively. T he formation of 9 and 16 requires the generation of five tetrahydrofuran an d four oxacyclic rings, respectively, in a single-pot operation.