Catalysis of the reaction: 3-(cis-5,6-dihydroxycyclohexa-1,3-dien-1-yl)propanoate + NAD+ = 3-(2,3-dihydroxyphenyl)propanoate + H+ + NADH. Also converts (2E)-3-(cis-5,6-dihydroxycyclohexa-1,3-dien-1-yl)prop-2-enoate to (2E)-3-(2,3-dihydroxyphenyl)prop-2-enoate.
2,3-dihydroxy-2,3-dihydro-phenylpropionate dehydrogenase activity