(1R,1′R,2S,2′S)‐2,2′‐Bis(1,1‐dimethylethyl)‐2,2′,3,3′‐tetrahydro‐1,1′‐bi‐1H‐isophosphindole and (1S,1′S,2R,2′R)‐2,2′‐Bis(1,1‐dimethylethyl)‐2,2′,3,3′‐tetrahydro‐1,1′‐bi‐1H‐isophosphindole