Perhydro-5,5-8a-trimethyl-2-naphthalenone is prepared by acid cyclization of carboxylic esters of formula ##STR1## having a double bond in one of the positions indicated by the dotted lines and wherein symbol R designates a C.sub.1 -C.sub.6 alkyl radical, X stands for a monovalent radical of formula P(O)(OR.sup.1).sub.2 or C(O)R.sup.2, R.sup.1 represents a C.sub.1 -C.sub.6 alkyl group and R.sup.2 is either a linear or branched alkyl group or a substituted or unsubstituted phenyl radical, and wherein the wavy line represents a C--C bond of cis or trans configuration, or of formula ##STR2## wherein the wavy lines and symbol R are defined as above, and R.sup.0 represents a C.sub.3 -C.sub.6 alkyl radical, preferably branched, followed by basic decarboxylation of the obtained product.
Perhydro-5,5-8a-trimethyl-2-naphthalenone是通过酸环化制备的,其酯的
化学式为##STR1##其中有一个由虚线表示的位置有双键,其中符号R代表C.sub.1-C.sub.6烷基基团,X代表
化学式P(O)(OR.sup.1).sub.2或C(O)R.sup.2的一价基团,R.sup.1表示C.sub.1-C.sub.6烷基团,R.sup.2是线性或支链烷基团或取代或未取代的苯基基团,其中波浪线表示顺式或反式构型的C--C键,或者是
化学式##STR2##,其中波浪线和符号R的定义如上所述,R.sup.0表示C.sub.3-C.sub.6烷基基团,优选是支链烷基基团,其次是通过所得产物的
碱性脱羧反应制备的。