| abstract |
There are described a process for the preparation of a compound of the formulan nwhereinn R is unsubstituted or substituted C 1 -C 12 alkyl, C 2 -C 4 alkenyl, C 2 -C 4 alkynyl, C 3 -C 6 cycloalkyl,naryl, heteroaryl or -SR 1 ; R 1 is unsubstituted or substituted C 1 -C 12 alkyl, C 1 -C 4 alkenyl, C 2 -C 4 alkenyl, C 2 -C 4 alkynyl,ncycloalkyl, aryl or heteroaryl; and X is a leaving group; which comprises n a) reacting a compound of the formulan nwherein R is as defined above, with a water-removing agent; or b) for the preparation of a compound (I) wherein X is halogen or a sulfonate, reacting ancompound of the formulan nwherein R is as defined for formula (I), with a halogenating agent or a sulfonylating agent; or c) for the preparation of a compound (I) wherein X is halogen, reacting a compoundn nwherein R is as defined for formula (I); andn R 2 and R 3 are for example, H, C 1 -C 6 alkyl, C 3 -C 6 cycloalkyl, phenyl or benzyl; nwith a compound of the formula halogen-C(=O)-O-C 1 -C 8 alkyl, halogen-C(=O)-O-aryl ornhalogen-C(=O)-O-benzyl; intermediates for the preparation of the compounds (II) to (IV) and (VI) and a method for thenpreparation thereof. |