185140-38-9Relevant academic research and scientific papers
Photosensitized oxygenation of twisted 1,3-dienes: Abnormally higher reactivity of vinyl hydrogen rather than allyl hydrogen toward singlet oxygen
Mori, Hajime,Ikoma, Keiichi,Isoe, Sachihiko,Kitaura, Kazuo,Katsumura, Shigeo
, p. 8704 - 8718 (1998)
As one of the novel examples to investigate the characteristic reactivity of significantly twisted 1,3-dienes, the photosensitized oxygenation of two types of significantly twisted 1,3-dienes, cis-βionol derivative 2 and acyclic derivative 11, is investigated. Photosensitized oxygenation of 2a-f and 11a-e revealed that the vinyl hydrogen Ha was more reactive than the allyl hydrogen Hb. Thus, phenyl derivative 2e and tert- butyl-substituted compound 11d selectively produced allenes 3e and 13d in 67% and 75% yield resulting from the ene reaction of the vinyl hydrogen Ha rather than allyl alcohols 4e and 14d resulting from the allyl hydrogen abstraction in 24% and 8% yield, respectively. Furthermore, in the case of methyl- substituted compound 11b, the extent of the inherent reactivity of the vinyl hydrogen Ha was similar to that of the allyl hydrogen Hc. On the basis of X- ray analysis and MM and MO calculations, the discovered abnormally higher reactivity of the vinyl hydrogen would be rationalized by considering mainly the large σ*-π orbital interaction between the vinyl C-H bond and another double bond in significantly twisted 1,3-dienes resulting from calculations of HOMO electron densities.
