(5R*, 9S*)- and (5R*, 9R*)-2,2,9-Trimethyl-1,6-dioxaspiro[4.4]non-3-ene and their Dihydro Derivatives as New Constituents of Geranium Oil

(5 R^*,9S^*)- and (5R^*,9R^*)-2,2,9-Trimethyl-1,6-dioxaspiro 4.4]non-3-ene ( 1a and 1b resp.) and their dihydro derivatives 2a and 2b are described as new constituents of geranium oil. The structures and configurations of 1a , 1b , 2a , and 2b , are based on spectra interpretation and syntheses. Also some other monoterpenoid constituents identified in the same boiling range are discussed.