Compounds for providing a long-lasting odor

A compound of formula

• in the form of any one of its stereoisomers or a mixture thereof, and wherein
• n is 1, 2, 3 or 4;
• the dotted line represents a single or a double bond,
• X is an oxygen atom or a N—R group wherein R is a hydrogen atom, a C1 to C4 alkyl group, a phenyl group or a benzyl group,
• R1 is a hydrogen atom or a C1 to C10 hydrocarbon group, optionally comprising from 1 to 5 oxygen atoms and/or one sulphur atom and/or one, two or three nitrogen atoms;
• R2 and R2′ are, independently from each other, a hydrogen atom, a C1 to C4 alkyl group or a CHR1XH group, or R2 and R2′ when taken together form a carbonyl group;
• R3 is hydrogen atom, a methyl or an ethyl group;
• R4 is a hydrogen atom, a COOR′ group or a C1-3 alkyl group optionally substituted by a COOR′ group wherein R′ is a C1-3 alkyl group;
• R5 are, independently from each other, a hydrogen atom or a methyl group;
• or
• R and R1, when taken together form a C4-6 azocycloalkyl group;
• or
• R1 and R2;
• when taken together form a C5-6 cycloalkyl group;
• or,
• R2 and R3, when taken together form a group of formula
• wherein the bold line is connected to the carbon atom of R2 and the hatched line to the nitrogen atom of R3.