Abstract
The photocyclization of 1,1'-dicycloalkenyls (1,1'-dicyclohexenyl, 1,1'-dicyclopentenyl, 1,1'-dicycloheptenyl and 1,1'-dicyclooctenyl) is studied. Irradiation at liquid nitrogen temperature does not show trans double bond band in IR spectra. Even though naphthalene and pyrene fluorescence are quenched very efficiently by 1, 1'-dicycloalkenyls, no or trace amount of cyclobutenes are accompanied. When acetophenone or benzophenone is used, cyclobutene is obtained only from 1,1'-dicyclohexenyls, 1,1'-dicycloheptenyl giving some adducts. Naphthalene and pyrene sensitizes adduct formation but not cyclization. From above observations, it is concluded that photocyclization occurs from the planar s-cis triplet state rather than twisted triplet, singlet excited state or vibrationally excited ground state in sensitized photocyclization of 1,1'-dicycloalkenyls.
1,1'-디시클로알케닐의 광고리화 반응을 형광 퀘ㄴ칭, 증감제등을 써서 연구하였다. 증감제를 쓰는 경우 이 디엔의 광고리화 반응은 비틀린 삼중상태나 평면구조의 트란스 삼중상태보다 높은 에너지 준위에 있는 평면구조의 s-시스 삼중상태에서 일어남을 알았다.