Patent GB-740081-A (GB)
Title: The production of lactones
Inventor: LACEY RICHARD NORMAN
Filed: 1952-04-30
Abstract: The invention comprises (1) the preparation of lactones of the general formula <FORM:0740081/IV(a)/1> or <FORM:0740081/IV(a)/2> by reacting in the presence of a condensation catalyst a hydroxy carbonyl compound of the formula <FORM:0740081/IV(a)/3> or <FORM:0740081/IV(a)/4> where R2 and R3 are alkyl, aryl, or hydrocarbonor oxa-hydrocarbon-substituted aryl groups, or R3 may also be hydrogen, R4 and R7 are alkyl groups or hydrogen atoms and R5 and R6 are alkyl groups, with an ester of the formula R.COCH2COOR1, where R is an alkyl, aralkyl, aryl or hydrocarbon-substituted aryl group and R1 is an alkyl group of 1-4 carbon atoms; and (2) as new compounds lactones of the above general formula wherein R is an alkyl group other than methyl, or an aralkyl or aryl group, R2 is alkyl or aryl, R3 is alkyl, aryl or hydrogen, R4 and R7 are alkyl or hydrogen and R5 and R6 are alkyl.  The reaction is preferably carried out at an elevated temperature in the presence of a catalyst comprising a secondary or tertiary or cyclic amine, or a salt of such an amine with a weak acid, or an alkali metal salt of a weak acid.  An inert diluent is preferably present which is suitably a solvent for the starting materials.  Preferably the solvent is one which is immiscible with water, which has a boiling-point of 70-150 DEG  C. and forms an azeotropic mixture with the water or alcohol eliminated by the reaction, which is thereby distilled off from the reaction. Specified hydroxy-carbonyl compounds which may be used as starting materials are acetoin, butyroin, benzoin, phenyl acetyl carbinol, benzoyl methyl carbinol, p-anisoyl phenyl carbinol, benzoyl-p-anisyl carbinol, isobutyraldol, alpha : alpha - dimethyl - b  - hydroxy - n - butyraldehyde and alpha : alpha-dimethyl-b -hydroxy isovaleraldehyde.  In examples: (1) butyroin is reacted with methyl acetoacetate using pyridine acetate as a catalyst to give the lactone of 4-propyloct-3-en-5-ol-2-on-3-carboxylic acid, characterized by its 2 : 4-dinitrophenyl hydrazone; by using n-butyl acetoacetate in place of methyl acetoacetate the lactone of 6 - propyldec - 5 - en - 7 - ol - 4 - on - 5 - carboxylic acid is obtained; (2) benzoin is reacted with methyl acetoacetate in the presence of piperidine to give the lactone of 4 : 5-diphenylpent - 3 - en - 5 - ol - 2 - on - 3 - carboxylic acid; the benzoin may be replaced by p-anisoyl phenyl carbinol to give the corresponding 4-anisyl compound; (3) benzoin is reacted with methyl benzoylacetate in the presence of piperidine acetate to give the lactone of 1-benzoyl-2 : 3-diphenylprop-1-en-3-ol-1-carboxylic acid; by using ethyl gamma-phenyl acetoacetate in place of methyl acetoacetate the lactone of 1 : 4 : 5-triphenylpent-3-en-5-ol-2-on-3-carboxylic acid is obtained; and (4) isobutyraldol is reacted with methyl acetoacetate in the presence of piperidine acetate to give the lactone of 5 : 5 : 7-trimethyloct - 3 - en - 6 - ol - 2 - on - 3 - carboxylic acid; by using alpha : alpha-dimethylbeta-hydroxy-n-butyraldehyde in place of isobutyraldol 5 : 5-dimethylhept-3-en-6-ol-2-on-3-carboxylic acid is obtained.  Specification 740,077 is referred to.