GB678230A - Cyclopropane carboxylic acid esters of cyclopentenolones and method of synthesizing same - Google Patents

Abstract

The invention comprises pyrethrin analogues of the formula <FORM:0678230/IV (b)/1> where R is an aliphatic, aryl or heterocyclic radical, R1 is an aliphatic, cycloalkyl or aryl radical and R11CO is the radical of chrysanthemum monocarboxylic acid. These are prepared by reacting a glyoxal R1.CO.CHO with a b -keto acid R.CH2.CO.CH2.COOH or salt thereof at pH 5-9, ring-closing the resultant ketone R1.CO.CHOH.CH2.CO.CH2.R with an alkali (e.g. sodium hydroxide) to form the cyclopentenolone and esterifying with chrysanthemum monocarboxylic acid or its derivatives such as the halide or anhydride. The glyoxal R1.CO.CHO may be made by selenium dioxide oxidation of the aldehyde R1.CH2.CHO or ketone R1.CO.CH3. The b -keto acid or salt is prepared by low-temperature hydrolysis of its ester and neutralization with carbon dioxide. Details are p given of the necessary experimental conditions for each step. Examples are given of the preparation of compounds where R1 is methyl and R is allyl, n-butyl, 2-butenyl, 3-butenyl, 2-isobutenyl and 2-isopentenyl; also of the compound where R is allyl and R1 is phenyl. The hydroxydiketones form anhydrodisemicarbazones. The cyclopentenolones are purified by conversion into their semicarbazones and regeneration from the latter. The cyclopentenolone (R=2-butenyl, R1=methyl) is a stereoisomer of natural cinerolone and gives on hydrogenation the same dihydrocinerolone as the latter. For esterification there may be used d-trans, dl-trans, dl-cis or mixtures of these chrysanthemum monocarboxylic acids. Other compounds are those in which R1 is methyl and R is phenyl, benzyl, p-chlorobenzyl and furfuryl, and those in which R is allyl and R1 is isobutenyl and cyclopropyl. Other groups specified for R are methyl, ethyl, propyl, isopropyl, sec. butyl, tert. butyl, amyl, hexyl, heptyl, octyl, nonyl, dodecyl, octadecyl, substituted alkyl, vinyl, chloroallyl, propynyl, pentadienyl, alkatrienyl, naphthyl, xylyl, phenylethyl, cinnamyl, cyclopropyl, cyclopentyl, cyclohexyl, cyclopentadienyl, cyclohexenyl and thienyl. Other groups specified for R1 are ethyl, propyl, isopropyl, butyl, amyl, octyl, decyl, heptadecyl, tolyl, xylyl, benzyl, phenylethyl, styryl, cyclohexyl and cyclopentyl, and substituted derivatives of these.