Correlation of structure and transannular interactions in a series of cage compounds

Abstract

A series of cage systems with general structure 7 were synthesized. By variation of bridge C, the distance between functional groups A and B could be changed systematically and the chemical consequences of these changes investigated. Thus, Diels-Alder reactions between benzoquinone and cyclic dienes ranging from cyclobutadiene to cycloheptadiene, and including cyclooctatetraene, yielded endo dienes which were subsequently converted to cage structures photochemically. This transformation results in compounds 8, 10, 15, 16, and 17 with two transannular carbonyl groups positioned at varying distances. Under ketalization conditions some of these compounds-the ones with larger bridges C which brought the keto groups closer together-gave cyclized products rather than simple ketals. In the other cases, monoketals formed which were reduced to endo alcohols and studied further. Molecular mechanics calculations on hydrocarbon models for these systems provided a more quantitative basis for interpretation of the experimental results. The distance between A and B in 7 varied with the size of bridge C. The calculated energies of simulated ring-closure reactions (40 -39 and 41 -39) became more favorable as the number of atoms in bridge C was increased. These results parallel the experimental trends.

Synthesis of Pentaoxa[5]peristylanes

“…On the other hand, the synthesis and chemistry of heterocyclic cage compounds have received less attention. However, there are some reports regarding the chemistry and synthesis − of oxa cage compounds in the literature. This class of heterocyclic cages is synthesized by intramolecular alkene−oxirane (2σ−2π) photocycloaddition, by transannular cyclization of suitable compounds, by tandem cyclization, by dehydration of diols having the proper stereochemistry, by base-promoted rearrangement, and by intramolecular etherification of the alkene bond with organoselenium reagents …”

Barriers to intramolecular hydride transfers in some polycyclic hydroxyketones

“…~~ In our hantls, the thermal c!-cloacltlition was not successful, but Barbor:tk ct aZ. 32 have recently reported that low yields may be obtained by heating the reactant. ; a t 50" for 2.5 weeks.…”

Synthesis of New Type Diacetal Trioxa-Cage Compounds via an Intramolecular Nucleophilic Addition of the Hydroxy Group to the Carbonyl Oxide Group

“…There are some reports regarding the chemistry and synthesis − of oxa-cage compounds in the literature. This class of heterocyclic cage compounds is synthesized by intramolecular alkene−oxirane (2σ−2π) photocycloaddition, by transannular cyclization of suitable compounds, by tandem cyclization, by dehydration of diols having the proper stereochemistry, by base-promoted rearrangement, and by intamolecular etherification of an alkene bond with organoselenium reagents .…”