Catalysis of the reaction: (6aR,11aR)-3,9-dihydroxypterocarpan + H(+) + NADPH + O(2) = (6aS,11aS)-3,6a,9-trihydroxypterocarpan + H(2)O + NADP(+). (6aS,11aS)-3,6a,9-trihydroxypterocarpan is also known as (-)-glycinol.