Palladium-Catalyzed Esterification-Hydroarylation Reactions of 2-Alkynylbenzaldehydes with Aryl Iodides in Methanol

Abstract

The reaction of 2-alkynylbenzaldehydes with aryl iodides in the presence of Pd(PPh₃)₄ and K₂CO₃ in refluxing methanol for 24 hours gave the dehydrogenation-addition products, methyl 2-(2,2-disubstituted-vinyl)benzoates in modest yields; together with the cyclization products, 3-methoxy-1-monosubstituted-methylene-3-hydroisobenzofurans in 3-18% yields.

palladium - coupling - esterification-hydroarylation - 2-alkynylbenzaldehydes

References

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Treatment of 2-iodobenzyl alcohol with phenylacetylene in the presence of catalytic amount of Pd(PPh₃)₄ and CuI, n-BuNH₂ as a base in Et₂O for 5 h gave compound 5a in 82% yield. The 2-alkynylbenzaldehyde 1a was obtained by oxidation of 5a with PCC in 91% yield.

11

Crystal data for 3aa: C₂₃H₂₀O₂; M = 328.39 g/mol, crystal size: 0.50 × 0.50 × 0.50 mm, monoclinic, space group P2₁/n, λ = 0.71073 Å, a = 9.7557 (6) Å, b = 11.9347 (7) Å, c = 15.7626 (9) Å, α = 90°, β = 99.370 (1)°, γ = 90°, V = 1810.77 (19) ų, Z = 4, D = 1.205 Mg/m³. µ = 0.076 mm^-1, T = 295 (2) K, θ range: 2.15-27.50°, reflections collected: 17775, independent reflections: 4167 (R_int = 0.0303), refinement method: full-matrix least-squares on F², final R values[ I> 2σ(I) ]: R1 = 0.0499, wR2 = 0.1234. Diffractometer: BRUKER SMART APEXCCD. Crystallographic data (excluding structure factors) for this structure have been deposited at the Cambridge Crystallographic Data centre as supplementary publication no. CCDC-223977, and may be obtained free of charge on application to CCDC, 12 Union Road, Cambridge CB2 1ED, UK [fax: [phone];
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12

Crystal data for 4b: C₁₇H₁₆O₃; M = 268.30 g/mol, crystal size: 0.27 × 0.23 × 0.02 mm, orthorhombic, space group Pca2₁, λ = 0.71073 Å, a = 20.9353 (13) Å, b = 8.6773 (5) Å, c = 7.7543 (5) Å, α = 90°, β = 90°, γ = 90°, V = 1408.66 (15) ų, Z = 4, D = 1.265 Mg/m³. µ = 0.086 mm^-1, T = 295 (2) K, θ range: 1.95-27.50°, reflections collected: 13064, independent reflections: 3220 (R_int = 0.0619), refinement method: full-matrix least-squares on F², final R values[ I > 2σ(I) ]: R1 = 0.0902, wR2 = 0.1693. Diffractometer: BRUKER SMART APEXCCD. Crystallographic data (excluding structure factors) for this structure have been deposited at the Cambridge Crystallographic Data center as supplementary publication no. CCDC-231702.

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