Interest in the preparation and reactions of phosphorus compounds containing an epoxygrouping has been generated by the discovery of phosphonomycin ('I_), a simple wide-spectrum antibiotic.' CH3 / "3"2 ,' '\ HI 'H 0 1 We wish to report the synthesis of epoxy-phospholanes and their rearrangement, catalysed by boron trifluoride, to stable Direct oxidation of the yields of epoxides have been trifluoroperacetic acid3 but enols and phospholan-3-ones. double bond of phosphol-Z-enes is known to be difficult.2 Small formed directly from the phospholene by prolonged treatment with treatment with m-chloroperbenzoic acid in refluxing dichloroethane for 24h in the presence of 2,4,6-tri-t-butylpheno14 gave us only starting material. We have found that high yields of epoxy-phospholanes can be obtained from phospholenes by formation of the bromohydrin followed by treatment with base. Reaction of &with N-bromoacetamide in aqueous media gave the bromohydrin (32, 93%) as a mixture of isomers, m.p. 150-157"(CCl~),5 r(CDCl3) 1.88-2.52 (5H,m), 4.13 (lH,broad s), 5.63-5.78 (lH,m), 7.27-8.07 (4H,m), 8.32 (3H,s). No splitting of the n.m.r. signal of the hydroxyl proton was observed using DMSO as solvent, indicating the presence of a tertiary alcohol.6 Similarly, 2b gave & (70%) b.p. 190-197°/0.6mn, as a mixture of isomers, T(CDCJ~) 5.55 (lH,s), -5.55-6.17 (2H,m), 7.43-8.25 (4!i,m), 8.48 (3H,s), 8.62 (3H,t,JHH 7Hz). Treatment of z with potassium acetate in acetone gave the epoxide (4a,80%). One isomer was obtained pure by fractional crystallisation from carbon tetrachloride. m.p.102-103°,~CDCls)