| 摘要 |
1,259,950. Acetoacetates. F. HOFFMANNLA ROCHE & CO. A.G. 12 Dec., 1968 [18 Dec., 1967], No. 42884/69. Divided out of 1,259,947. Heading C2C. Novel acetoacetates of the formula wherein R and R 1 are C 1-6 alkyl radicals, provided that when R is C 1-4 alkyl, R 1 is C 2-6 alkyl, are prepared by reacting the free alcohol with an acetoacetic acid ester or with diketene. The reaction with an acetoacetate may be effected in the presence of an acidic or alkaline catalyst with removal of the liberated alcohol by distillation. The reaction with diketene is carried out in the presence of a basic catalyst. An example, illustrating the process by which the novel esters may be prepared, describes the preparation of a known compound 3,7-dimethyl- 1,6 - nonodien - 3 - yl acetoacetate. 3 - Ethyl- 7 - methyl - 1,6 - nonodien - 3 - yl acetoacetate may be similarly prepared. A starting alcohol, 3,7-dimethyl-1,6-nonodien- 3-ol, may be prepared by condensing 3-methyl- 1-penten-3-ol with ethylacetoacetate in the presence of aluminium isoproxide to obtain 6- methyl-5-octen-2-one which is reacted with acetylene and the resulting 3,7-dimethyl-6- nonen-1-yn-3-ol partially hydrogenated to the required compound. |
