GB893322A - Lactonols - Google Patents

Abstract

The invention comprises lactonols of the general formula <FORM:0893322/IV (b)/1> in which R1 and R2 are hydrogen or C1-5 alkyl groups, at least one being such an alkyl group, and R3 is a hydrocarbon radical containing 2-9 carbon atoms, not more than seven being consecutive atoms in an acyclic chain, and being a mono- or di-substituted methyl group which may be alkyl, aralkyl or cycloalkyl. The lactonols may be prepared by reacting a maleic anhydride <FORM:0893322/IV (b)/2> with a Grignard reagent R3MgX at a temperature of from -95 DEG C. to +5 DEG C., or with an organic zinc halide R3ZnX or an organo cadmium compound R3CdR3, suitably at 70 DEG C.-90 DEG C., and in each case hydrolysing the addition product to convert the organo-metallic group therein to -OH. Examples (1)-(6) describe the preparation via a Grignard reagent of those lactonols wherein R1 and R2=CH3 and R3 is ethyl, n-propyl and its homologues up to n-heptyl, 3-dimethyl-propyl, diethyl-methyl, cyclohexyl, cyclohexyl-methyl, benzyl, phenethyl; R1 and R2=ethyl and R3 is n-butyl, pentyl or hexyl; R1 and R2=n-butyl and R3 is pentyl; and a mixture of 3- and 4-methyl-5-hydroxy-5-pentyl-2,5-dihydro furan-2-ones. Examples 7 and 8 describe the preparation of lactonols wherein R1 and R2=CH3 and R3 is n-pentyl using n-pentyl Zn bromide or R3=n-alkyl using di(n-alkyl)cadmium as reactant. Other values for R3 are also given. The lactonols may be dehydrated as described in Specification 893,321. The maleic anhydrides may be prepared by (1) a -alkylating a b -keto ester R1COCH2COOR with sodium and an alkyl halide R2X, reacting the product with NaCN and HCl, hydrolysing the so-formed cyanhydrin and dehydrating the resulting hydroxy dicarboxylic acid; (2) reacting a chloro-ketone R1CO.CH(R2)Cl with NaCN, treating the product with HCN in acetic anhydride yielding CH3COOC(R1)(CN).CH(R2)CN which is then hydrolysed and dehydrated; or (3) reacting a bromo-ester Br.CH(R1)COOR with a keto ester R12COCH2COOR, R12 being the group R2 defined above less a CH2- group, treating the product R1.CH(COOR).CH(COOR).COR12 with sodium amalgam and hydrolysing and dehydrating the product. The di-(n-alkyl)cadmium reactant used in (7) is prepared by refluxing n-alkyl magnesium bromide with cadmium chloride.