(2S,3R)-dihydrodehydrodiconiferyl alcohol + NADPH + H(+) <=> (R)-tetrahydrodehydrodiconiferyl alcohol + NADP(+)
(2s,3r)-dihydrodehydrodiconiferyl alcohol + nadph + h(+) <=> (r)-tetrahydrodehydrodiconiferyl alcohol + nadp(+)