6-oxabicyclo[3,2,0]heptanes for use as intermediates

摘要

The present invention relates to a compound of formula (XI):
wherein
R 1
is C 1-6 -alkyl, C 2-6 -alkenyl or C 2-6 -alkynyl; and
R 2
is C 1-4 -alkyl.
Y
each independently is halogen, C 1-4 -alkyl, C 1-4 -haloalkyl, C 1-4 -alkoxy, C 1-4 -haloalkoxy, phenyl, cyano or nitro; and m
is 0-5;
and further to a method for producing the same, comprising reacting a 2-oxocyclopentane carboxylic acid ester derivative of formula (XII)
wherein R 1 , R 2 , Y and m are as defined in claim 1, with formaldehyde or an equivalent thereof.