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Diels–Alder and other cycloadditions

16 real reactions from the literature: Diels–Alder on α,β-unsaturated ketones, conjugated dienes and cyclic conjugated dienes; hetero-Diels–Alder on cyclic conjugated dienes; and more. Each scheme shows starting materials, conditions and products, with the yield and reference where the source reports them.

Printable worksheets (PDF): Diels-Alder Reactions: with or without products; Other Pericyclic Reactions: with or without products.

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  1. Diels–Alder: 1,3-butadiene (a conjugated diene) and maleic anhydride (an α,β-unsaturated ester) with benzene gives tetrahydrophthalic anhydride (the cyclohexene adduct).
    Diels–AlderOrg. Synth. Coll. Vol. 4, p. 890

  2. Hetero-Diels–Alder: cyclopentadiene (a cyclic conjugated diene) and ethyl (NZ)-N-ethoxycarbonyliminocarbamate (an azo compound) with ether; Δ gives the hetero-Diels–Alder adduct.
    Hetero-Diels–AlderOrg. Synth. Coll. Vol. 5, p. 96

  3. Retro-Diels–Alder: a five-membered cycloalkene with 160 °C (gives 2 equiv cyclopentadiene) gives cyclopentadiene (the cyclic conjugated diene).
    Retro-Diels–AlderOrg. Synth. Coll. Vol. 4, p. 238

  4. [2+2] cycloaddition: 1,3-butadiene (a conjugated diene) with hν; sensitizer; trans >> cis gives 1,2-diethenylcyclobutane.
    [2+2] cycloadditionOrg. Synth. Coll. Vol. 5, p. 528

  5. Cheletropic extrusion: 2,3,4,5-tetraphenyl-2,4-cyclopentadien-1-one (a cyclopentadienone) and diphenylacetylene (an internal alkyne) with Δ; (–CO) gives hexaphenylbenzene (the aromatized product).
    Cheletropic extrusionOrg. Synth. Coll. Vol. 5, p. 604

  6. Diels–Alder: 2-cyclopenten-1-one (an α,β-unsaturated ketone) and 1,3-cyclohexadiene (a cyclic conjugated diene) gives the cyclohexene adduct. 66% yield.
    Diels–AlderOrg. Lett. 2005, 7, 5195

  7. Retro-Diels–Alder: a five-membered cycloalkene with Δ; 2 gives cyclopentadiene (the cyclic conjugated diene).
    Retro-Diels–AlderOrg. Synth. Coll. Vol. 5, p. 414

  8. Cheletropic extrusion: 2-phenyliodoniobenzoate (a diaryliodonium salt) and 2,3,4,5-tetraphenyl-2,4-cyclopentadien-1-one (a cyclopentadienone) with diethyl benzene, Δ; (–CO, –CO2) gives 1,2,3,4-tetraphenylnaphthalene (the aromatized product).
    Cheletropic extrusionOrg. Synth. Coll. Vol. 5, p. 1037

  9. Diels–Alder: 1,4-benzoquinone with 25 C, 2 weeks gives the cyclohexene adduct. 93% yield.
    Diels–AlderJ. Am. Chem. Soc. 1958, 80, 5006

  10. Diels–Alder: 2-methoxy-5-methyl-1,4-benzoquinone with 100 C gives the cyclohexene adduct. 86% yield.
    Diels–AlderJ. Am. Chem. Soc. 1951, 73, 2403

  11. Diels–Alder: 3-methyl-4-oxo-2-pentenoic acid (an α,β-unsaturated ketone) with SnCl4; 25 C gives the cyclohexene adduct. 73% yield.
    Diels–AlderPure Appl. Chem. 1973, 33, 45

  12. Diels–Alder: methyl 1H-pyrrole-1-carboxylate (a heteroarene) and ethynyl p-tolyl sulfone (a terminal alkyne) with 80 C gives the cyclohexene adduct. 36% yield.
    Diels–AlderTetrahedron Lett. 1993, 34, 7493

  13. Diels–Alder: an α,β-unsaturated ketone gives the cyclohexene adduct. 59% yield, mixture of 3 diastereomers yield.
    Diels–AlderOrg. Lett. 2001, 3, 1563

  14. Diels–Alder: cyclobutenone (an α,β-unsaturated ketone) with ZnCl2 gives the cyclohexene adduct. 86% yield.
    Diels–AlderJ. Am. Chem. Soc. 2014, 136, 2397

  15. Diels–Alder: a conjugated diene with 300 C gives the cyclohexene adduct and the cyclohexene adduct. regioisomer 2: 23% yield.
    Diels–AlderTetrahedron Lett. 1988, 29, 3283

  16. Diels–Alder: a cyclic conjugated diene and methyl (2E)-3-methyl-4-oxo-2-butenoate (an α,β-unsaturated ester) with 100 C gives the cyclohexene adduct. 61% yield.
    Diels–AlderJ. Am. Chem. Soc. 1985, 107, 4339