COMPARATIVE INVESTIGATIONS OF THE PHOTOINDUCED OXYGENATION OF (-)-CITRONELLOL

(-)-Citronellol 1 belongs to the natural terpene alcohols found in Bul garian rose oil of rosa damascena [1]. Reaction of 1 with photochemica lly generated singlet oxygen results in hydroperoxides, that must be r educed with sodium sulfite to get rose oxide 2. Transformation of the raw product in acidic solution gives a 40% mixture of (-)-cis- and (-) -trans-rose oxide 2 [2]. Rose oxide 2 is of particular interest in the fragrance industry [3]. Recently we were able to show [4] that allyli c alcohols can be obtained by photooxygenating alpha-pinene with dioxy gen in the presence of [Fe(tpp)]Cl 3a and 1-methylimidazole 4. The mai n goal of this paper is the comparison of selectivities found in photo chemical transformation of (-)-citronellol 1 with singlet oxygen and b y dioxygen photochemically activated in the presence of metal-porphyri nates.