5,7‐Dihydro‐3‐(2‐(1‐(phenylmethyl)‐4‐piperidinyl)ethyl)‐6H‐pyrrolo(3,2‐ f)‐1,2‐benzisoxazol‐6‐one: A Potent and Centrally‐Selective Inhibitor of Acetylcholinesterase with an Improved Margin of Safety.