Reading a scheme

Olefination

16 real reactions from the literature: Wittig on phosphonium salts, aliphatic aldehydes and hemiacetals; Horner–Wadsworth–Emmons on phosphonate esters and thioesters. Each scheme shows starting materials, conditions and products, with the yield and reference where the source reports them.

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  1. Wittig: triphenyl(4-triphenylphosphaniumylbutyl)phosphanium (a phosphonium salt) with 2.2 equiv.; acetone gives 2,7-dimethyl-2,6-octadiene (the trisubstituted alkene). 81% yield.
    WittigOrganometallics 2014, 33, 3235

  2. Horner–Wadsworth–Emmons: triethyl phosphonoacetate (a phosphonate ester) and pyruvic aldehyde dimethyl acetal (a methyl ketone) with 1) K2CO3 / H2O; 2) HCl / H2O gives ethyl (2E)-3-methyl-4-oxo-2-butenoate (the (E)-alkene). 85% yield.
    Horner–Wadsworth–EmmonsJ. Am. Chem. Soc. 2004, 126, 5984

  3. Wittig: triphenyl(phenylmethyl)phosphonium (a phosphonium salt) with 1); 2) gives [(E)-1,4-diphenylbut-1-en-3-yn-2-yl]benzene (the trisubstituted alkene). 80% yield.
    WittigChem. Commun. 2019, 55, 7808

  4. Horner–Wadsworth–Emmons: methyl diethylphosphonoacetate (a phosphonate ester) with 1); 2) gives methyl (E)-4,4-dimethyl-5-oxohept-2-enoate (the (E)-alkene). 83% yield.
    Horner–Wadsworth–EmmonsOrg. Lett. 2008, 10, 1183

  5. Wittig: 2,2,2-trifluoroacetophenone (an aryl ketone) and 2-oxopropyl(triphenyl)phosphanium (a phosphonium salt) with Et3N; DMF; 80 °C gives (E)-4-phenyl-5,5,5-trifluoro-3-pentene-2-one (the trisubstituted alkene). 90% yield.
    WittigOrg. Lett. 2016, 18, 3538

  6. Horner–Wadsworth–Emmons: hydroxyacetone (a methyl ketone) and diethyl (cyanomethyl)phosphonate (a phosphonate ester) with 2 equiv LiOH gives (e)-4-hydroxy-3-methylbut-2-enenitrile (the (E)-alkene). 86% yield.
    Horner–Wadsworth–EmmonsTetrahedron Lett. 2003, 44, 1333

  7. Wittig: propyltriphenylphosphonium bromide (a phosphonium salt) and ethyl levulinate (a methyl ketone) with 1) nBuLi, THF, 0 C; 2) add ketoester gives ethyl (E)-4-methylhept-4-enoate (the trisubstituted alkene). 52% (E) yield.
    WittigTetrahedron Lett. 2009, 50, 5719

  8. Horner–Wadsworth–Emmons: a thioester with 1) DIBAL-H; 2) gives the (E)-alkene.
    Horner–Wadsworth–EmmonsRealOChem worksheet

  9. Wittig: ethyl(triphenyl)phosphonium (a phosphonium salt) with 1); 2) gives cis-2-phenyl-2-butene (the trisubstituted alkene). 73% yield.
    WittigJ. Org. Chem. 2015, 80, 11388

  10. Wittig: isopropyltriphenylphosphonium (a phosphonium salt) and 1-(4-methylphenyl)ethanone (an aryl ketone) with tBuOK; DMSO; PhMe; 110 °C gives 1-methyl-4-(3-methylbut-2-en-2-yl)benzene (the tetrasubstituted alkene). 86% yield.
    WittigOrg. Lett. 2019, 21, 807

  11. Wittig: (ethoxycarbonylmethyl)triphenylphosphonium (a phosphonium salt) with 1); 2); 1 equiv. gives ethyl 3-methyl-4-oxopent-2-enoate (the trisubstituted alkene). 55% yield.
    WittigGreen Chem. 2017, 511

  12. Wittig: phenylglyoxal (a dialkyl ketone) and (3,3-dimethyl-2-oxobutyl)-triphenylphosphanium (a phosphonium salt) with tBuOK; PhMe gives (E)-5,5-dimethyl-1-phenylhex-2-ene-1,4-dione (the trans-1,2-disubstituted alkene). 82% yield.
    WittigJ. Chem. Soc., Perkin Trans. 1 1996, 2837

  13. Wittig: 1-(4-methylphenyl)ethanone (an aryl ketone) and (3-bromopropyl)triphenylphosphonium (a phosphonium salt) with 2 equiv NaH gives 1-(1-cyclopropylideneethyl)-4-methylbenzene (the tetrasubstituted alkene). 83% yield.
    WittigJ. Chem. Soc., Chem. Commun. 1994, 499

  14. Wittig: an aliphatic aldehyde with MePPh3+I-, NaHMDS gives the terminal alkene.
    WittigOrg. Lett. 2005, 7, 705

  15. Wittig: 2-hydroxytetrahydropyran (a hemiacetal) gives (E)-ethyl 7-hydroxy-2-methyl-2-heptenate (the trisubstituted alkene).
    WittigJ. Org. Chem. 2002, 67, 9443

  16. Wittig: an aliphatic aldehyde with Check, some Woodward paper gives the trans-1,2-disubstituted alkene.
    WittigRealOChem worksheet