Conrotatory

In a conrotatory mode of an electrocyclic reaction (a class of organic chemical reactions) the substituents located at the termini of a conjugated double bond system move in the same (clockwise or counter clockwise) direction during ring opening or ring closure.

example: example: upon heating cis-3,4-dimethylcyclobutene converts exclusively to trans,cis-2,4-hexadiene whereas trans-3,4-dimethylcyclobutene yields trans,cis-2,4-hexadiene.

opposite to disrotatory