692-47-7Relevant articles and documents
cis-2,3-Di-tert-butylcyclopropanones
Sorensen,Sun
, p. 1030 - 1040 (1997)
The preparation of the strained cis-2,3-di-tert-butylcyclopropanone 2 from the acyclic compound, α,α′-dibromodineopentyl ketone 1, using a previously reported methodology, is dramatic evidence of both the existence of oxyallyl intermediates in the mechanism of this reaction, and of the integrity with which oxyallyls ring-close to cyclopropanones by a disrotatory route. Because of the bulky cis substituents, cyclopropanone 2 exhibits a number of unusual spectroscopic features (as compared to the trans isomer 5). With the aid of ab initio calculations on 2 and 5, it can be shown that the C2 - C3 bond in 2 interacts with the carbonyl π-orbitals, thus causing the carbonyl oxygen to bend 12° out of the plane; this interaction is absent in 5 and the latter has a planar carbonyl group. As with other cyclopropanones, 2 can be photochemically decarbonylated. This process itself appears to be stereospecific even though highly strained alkenes are produced. Cyclopropanone 2 is thermally rearranged to the trans isomer 5 and the kinetics for this are reported; our favoured mechanism involves oxyallyl intermediates. Other reactions of 2 also appear to proceed through these oxyallyl species; for example, alcohols initially add to 2 to give α-alkoxy enols, solutions of 2 enter into very facile diene cycloadditions, and the dimerization of neat 2 also appears to involve these oxyallyl species.
Photochemistry of Alkenes. 8. Sterically Congested Alkenes
Kropp, Paul J.,Tise, Frank P.
, p. 7293 - 7298 (2007/10/02)
A study of photobehavior of the sterically congested tri- and di-tert-butylethenes 9, 21, and 25 has afforded additional insights into the excited singlet state behavior of alkenes.In pentane solution the carbene-derived products 11, 12, 24, and 32 were formed, respectively.In methanol tri-tert-butylethene (9) afforded additionally ether 14 and the rearranged alkenes 15 and 16 derived from protonation of carbene intermediate 10. 1,1-Di-tert-butyl analogue 21 afforded no detectable ether or rearranged alkene products.However, irradiation in methanol-O-d resulted in incorporation of deuterium at the vinyl positions of 21 recovered after partial conversion, apparently from deuteration-deprotonation of carbene intermediate 22.By contrast, 1,2-di-tert-butyl isomer 25 afforded no products attributable to protonation of the corresponding carbene intermediate 23 but gave ether 35b via 1,2 addition of methanol across the double bond of 25, perhaps involving protonation of the highly polarizable orthogonal 1(?,?*) intermediate.
