| abstract |
Unsatd. bicyclic ketones, useful as starting materials for macrocyclic ketones, esp. cyclopentadecanone ("EXALTON" (RM)) and 3-Me-cyclopentadecanone-1 (muskone) which are known as perfumes, of formula (I) (where R is H or Me) are prepd. by reacting cyclododecanone with a dialkyl carbonate O=C(OA1R)2 (where Alk is lower alkyl); reacting the beta-ketocarboxylic acid ester obtd. of formula (II) with an ester of formula: CH2=CRCOOR' (where R' is lower alkyl), in an alkaline medium to produce an ester which is saponified under alkaline conditions, to a ketocarboxylic acid of formula II: -COO Alk is -CH2CHRCO2 followed by reduction to corresp. hydroxy-carboxylic acid, and ring-closure to lactone, using (1) NaBH4, (2) H2SO4, and dehydration of lactone, e.g. with polyphosphoric acid. |