Upon treatment with aqueous alkali. the Diels-Alder adducts 2 and 4 of dich
loromethylenepropane-dinitrile (1) with cyclopentadiene and anthracene resp
. are converted into 3-chloro-bicyclo[2.2.1]hepta-2,5-diene-2-carbonitrile
(3) and 12-chloro-9,10-dihydro-ethenoanthracene-11-carbonitrile (5). resp.
The reaction may be brought about by other nucleophiles as well and involve
s the fragmentation of an intermediate beta -chloroimidate anion. 3 is a ed
uct for substituted norbornenes such as cyanoketone 18.