bases have been used to isomerize terminal epoxides successfully, however.(5) Acyclic disubstituted epoxides undergo deprotonation at the least substituted site (unless a conjugated double bond can be formed; see equation (9) below) with high selectivity for trans double bonds. (6) Five- and six-membered rings containing epoxides afford allylic alcohols upon treatment with amide bases; however, reactions of medium-ring epoxides may be complicated by competitive transannular C–H insertion or ketone formation. (7) Trisubstituted epoxides do not easily undergo metalation in the ring. As a result, allylic alcohols are formed from these substrates without competitive carbenoid transformations. The use of bulky aluminum amide bases facilitates elimination at the substituent cis to hydrogen, which occurs from the less sterically hindered epoxide-base complex. (8) Suitably substituted unsaturated epoxides may undergo vinylogous elimination, which leads to conjugated allylic alcohols. Substituted vinyl epoxides undergo 1,4-elimination in some but not all cases; however, epoxides with β unsaturation eliminate cleanly to give conjugated allylic alcohols. (9) Experimental conditions and procedure Typical conditions Lithium amides are usually prepared in the laboratory through the addition of a titrated solution of n-butyllithium in hexanes to a solution of the amine in ether. Dry glassware and inert atmosphere are required for these reactions. Alternatively, lithium amides may be prepared by the direct action of lithium on the corresponding amine. Typical temperatures for isomerization reactions employing lithium amides are between 0 °C and reflux (ether/hexane solvent mixtures derived from the synthesis of the lithium amide are usually used directly for isomerization reactions). An excess of the base is employed to account for impurities that consume base and reaction of the base with the ether solvent. Care should be taken when HMPA is added to lithium amide reactions, as it is a known animal carcinogen. Organolithium reagents may also be used; however, lower temperatures are required to avoid decomposition of the base. These reactions are most often run in hexanes. Aluminum amides, which are bulkier and sometimes more selective than lithium amides, are prepared from the corresponding lithium amides and diethylaluminum chloride. Reactions are usually carried out at 0 °C in an inert atmosphere, with benzene as the solvent. Example procedure (10) A benzene solution of 1 eq of diethylaluminum chloride was added dropwise at 0° to a solution of 1 eq of lithium 2,2,6,6-tetramethylpiperidide prepared in the usual fashion in benzene. The resulting slurry was stirred for 30 minutes and used immediately. To