NEW MATERIAL: Mixture in which a compound of formula I and a compound of formula II (R is 1-4C alkyl) are mixed in a ratio of at least 1.1:1, especially 2.2-3.0:1.

EXAMPLE: 2-Methoxy-9-methylene-2,6,6-trimethyl-bocyclo[3,3,1]nonane.

USE: Perfume, having strong, natural, warm perfume of tobacco, ambergris, and wood, a composition diffuses the perfume and is used in all perfume consuming products including eau de Cologne, extract, lotion, and toothpaste.

PROCESS: Dihydro-α-ionone di-C alkylketal or dihydro-α-ionone C alkylenol ether is cyclized using a catalytic amount of a strong acid to obtain a mixture of a compound of formula I and a compound of formula II.