CORRECTION OF THE STEREOCHEMICAL ASSIGNMENT OF THE BENZILIC ACID CENTER IN (R)-(-)-3-QUINUCLIDINYL (S)-(-4-IODOBENZILATE [(R,S)-4-IQNB]())

Radioiodinated (R)-quinuclidinyl-4-iodobenzilate (4IQNB) is a high aff inity muscarinic antagonist which has been utilized for in vitro and i n vivo assays, and for SPECT imaging in humans. 4IQNB exists in four d ifferent diastereomeric forms, since there are two asymmetric centers at the quinuclidinyl and benzilic acid centers. Based upon our in vivo studies, we have determined that the absolute stereochemistry previou sly assigned to the benzilic center was incorrect for the diastereomer that had been previously referred to as '(R)-quinuclidinyl-(R)-4-iodo benzilate' [(R,R)-4IQNB]. The correct designation for this diastereome r is '(R)-quinuclidinyl-(S)-4-iodobenzilate' [(R,S)-4IQNB]. (C) 1997 E lsevier Science Ltd.