Synthesis Of Triethyl Ammonium Hydrobromide To a stirred, -78°C, 0.2M solution of N-tertbutyldimethylsilanyl-4-bromo azetidinone in THF  (0.5g, 1.894mM in 10ml), was added triethylamine (0.26ml, 1.894mM). Thioacetic acid (0.14g, 1.894mM) was added dropwise over 20 minutes forming a pale yellow solution, before the reaction mixture was allowed to warm to ambient temperature over 2 hours and the solvent removed by reduced pressure rotary evaporation. Ice cold diethyl ether (25ml) was added with trituration causing precipitation of the product as pale yellow crystals (0.32g, 93%, mp: 181-183°C).