Ether from alkenes

Dehydrohalogenation of Alkyl Halides Dehalogenation of 12-Dihalides Dehydration of Alcohols Alkenes from Ethers... 

SECTION 204 ALKENES FROM ETHERS, EPOXIDES AND THIOETHERS... 

See Ref. 150, p. 136, for reagents that produce alkenes from p-halo ethers and esters, and from halohydrins. 

Alkenes from p-oxygenated selenidesS /J-Phenylseleno lactones, ethers, and alcohols are converted into alkenes on treatment with ClSi(CHj)j and Nal in C HiCN. Hydriodic acid (formed by inadvertent hydrolysis) may play a role this acid cun effect this reaction, but in lower yield. This elimination thus reverses cyclo-(unclionali/ations induced by C6H5ScX (cf Na-NH3, 9, 26), and in addition provides a stereospecific route to alkenes by way of/l-hydroxv selenides. lixnmplc ... 

Ab initio molecular orbital calculations, coupled with activation energies and entropies from experimental data, have been employed to determine the nature of the intermediates in the reaction of singlet oxygen with alkenes, enol ethers, and enamines.214 Allylic alkenes probably react via a perepoxide-like conformation, whereas the more likely pathway for enamines involves a zwitterionic cycloaddition mechanism. The reactions of enol ethers are more complex, since the relative stabilities of the possible intermediates (biradical, perepoxide, and zwitterionic) here depend sensitively on the substituents and solvent polarity. 

Fig. Synthesis of an alcohol from an alkene using mercuric acetate. Alkenes to Ethers...

When bromine is added to two beakers, one containing phenyl isopropyl ether and the other containing cyclohexene, the bromine color in both beakers disappears. What observation could you make while performing this test that would allow you to distinguish the alkene from the aryl ether ... 

Asymmetric hydroboration.1 Hydroboration of 1-phenyl-1-cyclopentene with IpcBH2 (100% ee) results in a dialkylborane (1) containing the traws-2-phenylcyclopentyl group of 100% ee. However, hydroboration of prochiral trisubstituted alkenes usually results in alkylisopinocampheylboranes of 50-85% ee. Most of these products are solids, and selective crystallization (usually from ether) can give the optically pure dialkyboranes. In some cases resolution can be achieved by allowing the impure borane to age for several... 

Nucleophilic attack on ( -alkene)Fp+ cations may be effected by heteroatom nucleophiles including amines, azide ion, cyanate ion (through N), alcohols, and thiols (Scheme 39). Carbon-based nucleophiles, such as the anions of active methylene compounds (malonic esters, /3-keto esters, cyanoac-etate), enamines, cyanide, cuprates, Grignard reagents, and ( l -allyl)Fe(Cp)(CO)2 complexes react similarly. In addition, several hydride sources, most notably NaBHsCN, deliver hydride ion to Fp(jj -alkene)+ complexes. Subjecting complexes of type (79) to Nal or NaBr in acetone, however, does not give nncleophilic attack, but instead results rehably in the displacement of the alkene from the iron residue. Cyclohexanone enolates or silyl enol ethers also may be added, and the iron alkyl complexes thus produced can give Robinson annulation-type products (Scheme 40). Vinyl ether-cationic Fp complexes as the electrophiles are nseful as vinyl cation equivalents. ... 

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