... I: SYNTHESIS OF MONOFLUOROPHYTOSTEROLS Toni B. Kline and Glenn D. Prestwich ... r FF . FRFRIR 2 3 4 NMR = HO The preparation of 26-fluorositosterol (~, 24 R) and 26-fluoroclionosterol (22, 24 S) from stigmasterol Q) is shown in Scheme 1. Protection of the A/B ring as the iso-methyl * Fellow of the Alfred P. Sloan Foundation (1981-1983) and Camille and Henry Dreyfus Teacher- Scholar (1981-1986). Address correspondence to this author. ...