Isolation of Ozonides from Gas-Phase Ozonolyses of Terpenes

Ozonolyses of (−)-β-pinene (1) and of (+)-sabinene (6) in the gas phase afforded the corresponding ozonides 6,6-dimethylbicyclo[3.1.11,5]heptane[2-spiro-3]-1,2,4-trioxolane (2) and 5-isopropylbicyclo[3.1.01,5]hexane[2-spiro-3]-1,2,4-trioxolane (7), which were isolated as mixtures of two diastereomers each. Major products were the corre sponding ketones 6,6-dimethyl-2-oxobicyclo[3.1.11,5]heptane (3) and 5-isopropyl-2-oxobicyclo[3.1.01,5]hexane (8). Additional products were the lactones 7,7-dimethyl-2-oxa-3-oxobicyclo[4.1.11,6]octane (4) and 7,7-dimethyl-3-oxa-2-oxobicyclo[4.1.11,6]octane (5) derived from β-pinene (1) as well as 6-isopropyl-2-oxa-3-oxobicyclo[4.1.01,6]heptane (9) and 6-isopropyl-3-oxa-2-oxobicyclo[4.1.01,6]heptane (10) derived from sabinene (6).