Isolation of Ozonides from Gas-Phase Ozonolyses of Terpenes

Abstract

Ozonolyses of (−)-β-pinene ( 1 ) and of (+)-sabinene ( 6 ) in the gas phase afforded the corresponding ozonides 6,6-dimethylbicyclo[3.1.1 1,5 ]heptane[2-spiro-3]-1,2,4-trioxolane ( 2 ) and 5-isopropylbicyclo[3.1.0 1,5 ]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[3.1.1 1,5 ]heptane ( 3 ) and 5-isopropyl-2-oxobicyclo[3.1.0 1,5 ]hexane ( 8 ). Additional products were the lactones 7,7-dimethyl-2-oxa-3-oxobicyclo[4.1.1 1,6 ]octane ( 4 ) and 7,7-dimethyl-3-oxa-2-oxobicyclo[4.1.1 1,6 ]octane ( 5 ) derived from β-pinene ( 1 ) as well as 6-isopropyl-2-oxa-3-oxobicyclo[4.1.0 1,6 ]heptane ( 9 ) and 6-isopropyl-3-oxa-2-oxobicyclo[4.1.0 1,6 ]heptane ( 10 ) derived from sabinene ( 6 ).