E2 and E1 elimination of a leaving group
11 real reactions from the literature, on cyclic ethers, vicinal dihalides, primary alkyl bromides and tertiary sulfonate esters. Each scheme shows starting materials, conditions and products, with the yield and reference where the source reports them.
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Leaving group elimination: 2-bromo-1,1-diethoxyethane (a primary alkyl bromide) with tBuOK, Δ gives 1,1-diethoxyethene (the enol ether).
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Leaving group elimination: a cyclic ether with 1) DBU; 2) HCl workup gives the six-membered cycloalkene. 80% yield.
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Leaving group elimination: 2-cyano-1,3-diphenylpropan-2-yl methanesulfonate (a tertiary sulfonate ester) with DBU; MeCN gives (E)-2-benzyl-3-phenylprop-2-enenitrile (the trisubstituted alkene).
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Leaving group elimination: a secondary alkyl bromide with tBuOK; THF gives the five-membered cycloalkene. 88% yield.
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Leaving group elimination: a cyclic ether with H2SO4; H2O THF gives the tetrasubstituted six-membered cycloalkene. 99% yield.
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Leaving group elimination: a cyclic ether with hindered base; LiHMDS; then H3O+ workup gives the trisubstituted six-membered cycloalkene. 80% yield.
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Leaving group elimination: a vicinal dihalide with KOH; MeOH gives 1,2-dibromocyclohex-1-ene (the tetrasubstituted six-membered cycloalkene). 71% yield.
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Leaving group elimination: 3-chloro-1,1-diethoxypropane (a primary alkyl chloride) with KOH gives 3,3-diethoxy-1-propene (the terminal alkene).
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Leaving group elimination: 2-bromo-2-methyldodecanoyl bromide (a vicinal dihalide) with KOtBu; tBuOH, Δ gives tert-butyl 2-decylacrylate (the 1,1-disubstituted alkene).
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Leaving group elimination: 1,2-dibromocyclohexane (a vicinal dihalide) with i-PrOH, NaH, 100-110 °C; triethylene glycol dimethyl ether gives 1,3-cyclohexadiene (the cyclic conjugated diene).
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Leaving group elimination: 7-chloro-7-methyldispiro[2.0.24.13]heptane (a tertiary alkyl chloride) with KOtBu gives 7-methylidenedispiro[2.0.2~4~.1~3~]heptane (the 1,1-disubstituted alkene).