The invention concerns new 3-methyl-5-keto-.alpha.,.omega.-alkene-dioic acids of the general formula ##STR1## wherein the double bond is in one of the positions indicated by the broken lines, R.sub.1 and R.sub.2 independently of one another are a hydrogen atom or a C.sub.1 -C.sub.4 -alkyl group, x is an integer from 9 to 11 and y and z independently of one another are 1 or 2, but cannot both be 1; a process for their preparation and their use for the preparation of macrocyclic .beta.-methyl ketones which are valuable fragrances.
本发明涉及一种新的3-甲基-5-酮-.alpha.,.omega.-烯二酸,其一般式为##STR1##其中双键位于所示断裂线之一的位置,R.sub.1和R.sub.2分别独立地是氢原子或C.sub.1-C.sub.4-烷基,x为9至11的整数,y和z独立地为1或2,但不能都为1;其制备方法以及它们用于制备有价值的
香料的大环β-甲基酮。