1. Interaction between Oxygen Lone-Pair Orbitals of Ether and α,β-Unsaturated Ketone Functions in 3,5,6-Trimethylidene-7-oxabicycloheptan-2-one and 3,6-Dimethylidene-7-oxabicycloheptane-2,5-dione: A PE-Spectroscopic Investigation

Article abstract of DOI:10.1002/hlca.19900730102

Controlled ozonolysis of 2,3,5,6-tetramethylidene-7-oxabicyclo<2.2.1>heptane (1) afforded 3,5,6-trimethylidene-7-oxabicyclo<2.2.1>heptan-2-one (2).Ozonolysis of 2 gave a 1:1 mixture of 3,5-dimethylidene-7-oxa-bicyclo<2.2.1>heptane-2,6-dione (3) and 3,6-dimethylidene-7-oxabicyclo<2.2.1>heptane-2,5-dione (4).The He(Iα) photoelectron (PE) spectra of 2 and 4 have been recorded.Comparison with the PE data of related systems, and with the result of ab initio STO-3G calculations, confirm the existence of significant through-bond interactions between the oxygen lone-pair orbital n(CO) of the carbonyl functions and n(O) of the O(7) ether bridge.