| 摘要 |
A process for preparing a compound of formula (I) which comprises <CHEM> or a salt, acylate or sulphonate derivative thereof; wherein R<1> is an optionally substituted aryl group, R<2>, R<3>, R<4> and R<5> are selected from hydrogen, C1-4 alkyl, C1-4 alkanoyl or -CO2R<a> wherein R<a> is C1-4 alkyl or R<2> and R<3> or R<4> and R<5> together with the carbon atom to which they are attached form a C3-6 cycloalkyl ring, provided that at least R<2> and R<3> or R<4> and R<5> are not both hydrogen and that not more than two of R<2>, R<3>, R<4> and R<5> are C1-4 alkanoyl or -CO2R<a>; which process comprises either; a) reacting a compound of formula (II) <CHEM> wherein R<2>, R<3>, R<4> and R<5> are as defined in relation to formula (I) with a compound of formula (III): R<1>COCN (III) wherein R<1> is as defined in relation to formula (I) in the presence of a base and a Lewis acid; or b) reacting a compound of formula (VI) <CHEM> with a compound of formula (X) <CHEM> wherein R<1> is as hereinbefore defined, in the presence of a Lewis acid; or c) where R<2>, R<3>, R<4> and R<5> are the same, reacting a compound of formula (XI) <CHEM> with a compound of formula R<2>X<1> in the presence of a base, wherein X<1> is a leaving group. Certain compounds of formula (I) are novel and these and their use as herbicides form another aspect of the invention. |
