GB670514A - Improvements in or relating to a process of preparing new spiro barbituric acid compounds and the spiro barbituric acid compounds resulting from such process - Google Patents

Abstract

Spiro-barbituric acids and salts of formula <FORM:0670514/IV (b)/1> in which R is hydrogen or methyl and R1 and R2 are methyl or ethyl, but R is hydrogen when both R1 and R2 are ethyl and R is methyl when both R1 and R2 are methyl, and X is hydrogen or a metal, are prepared by condensing a 1 : 1 - dicarbethoxycyclopentane with urea to give the barbituric acid directly or with guanidine to give an iminobarbituric acid which is then hydrolysed, the barbituric acid being, if desired, treated with a base to give the metal salt. In the examples: (1) 3-methylacetonylacetone is reduced to 3-methyl-2:5-hexanediol, which is treated with hydrogen bromide to give 3-methyl-2:5-dibromohexane, which is condensed with ethyl malonate to give 1 : 1-dicarbethoxy-2 : 3 : 5-trimethylcyclopentane, condensation of which with guanidine affords spiro - [2 : 3 : 5 - trimethylcyclopentane - 1 : 51-(21 - imino) barbituric acid], which is hydrolysed to spiro-[2 : 3 : 5 - trimethylcyclopentane - 1 :51-barbituric acid], the sodium salt of the latter is formed (2); (3) a -allyldiethyl ketone is reduced (aluminium isopropoxide) to 4-methyl-1-heptene-5-ol, from which is prepared 4-methyl-2 : 5-dibromoheptane, which is condensed with ethyl malonate as above, the product treated with guanidine, and the iminobarbituric acid hydrolysed to spiro-(2-ethyl-3 : 5-dimethylcyclopentane-1 : 51-barbituric acid), the sodium salt of which is prepared (4); (5) 1-methylallylacetonitrile (from 1-methylallyl chloride and acetonitrile) is treated with ethyl magnesium bromide to give 5-methyl-6-heptene-3-one, which is reduced to the alcohol, the latter treated with hydrogen bromide to give 2 : 5-dibromo-3-methylheptane, which is converted to the cyclopentane - 1 : 1 - dicarboxylic ester and reacted with urea to give spiro-(2 : 3-dimethyl-5-ethylcyclopentane-1 : 51-barbituric acid); (6,7) propionaldehyde is treated with acetylene dimagnesium bromide to give 4-octyne-3 : 6-diol, which is reduced to octane-3 : 6-diol and converted to 3 : 6-dibromo-octane, the latter being converted to the barbituric acid as in the last example; (8) acetonitrile is condensed with allyl bromide to give allylacetonitrile, which is treated with ethyl magnesium bromide to give 1-heptene-5-one, which is reduced to 1-heptene-5-ol, converted to 2 : 5-dibromoheptane, which is converted to the barbituric acid as in example (5).