... CF3 d F3 J ! 1 1 1 Scheme I ... A rotamer interconversion kinetics study of 1A and 1B was carried out previously.2 However, no attempt was made to Journal of Pharmaceutical Sciences I 631 Vol. 79, No. 7, Ju/y 1990 Page 5. \ / 4(A*B) A Scheme 111 ...