| Popis: |
The thermolysis of 1,1′-disubstituted dicyclopropyl ethers with substituents AcO, OH (3a); MeO, OH (3b) and HO, OH (3c) has been studied, together with the sulfide 3d, the thioether analogue of 3c. It is found that the cyclopropyl ethers 3 easily split off cyclopropanone, which cannot be isolated as such because of rapid oligomerisation. This is accompanied by some ring-opening to a 2-hydroxyallyl cation, CH2C(OH)CH2, thus explaining the ultimate formation of substituted acetones. No evidence for the transient existence of O-protonated cyclopropanone , isomeric with the hydroxyallyl cation, could be obtained. The sulfide 3d behaves entirely differently: on heating it gives the spirocyclic sulfur compounds 12 and 13. The formation of these products is explained in terms of d-orbital participation of sulfur in the stabilisation of an intermediate cyclo-propylsulfinium ion. |
