A Convenient Protocol for the α-Iodination of α,β-Unsaturated Carbonyl Compounds with I₂ in an Aqueous Medium

Abstract

A variety of cyclic and acyclic α,β-unsaturated carbonyl compounds undergo α-iodination exclusively, in high yields, with I₂ in aqueous THF catalyzed by DMAP and quinuclidine.

Key words

α,β-unsaturated carbonyl compounds - α-iodination - aqueous medium - regioselective

References

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15

Compound 2l was extracted with acetonitrile.

16

Selected data:
Compound 2f: ¹H NMR (300 MHz, CDCl₃): δ = 6.83 (d, J = 2.1 Hz, 1 H, CHH=C), 6.86 (d, J = 2.1, 1 H, CHH=C), 7.46 (t, J = 6.8 Hz, 2 H, Ar), 7.59 (t, J = 7.5 Hz, 1 H, Ar), 7.81 (d, J = 7.2 Hz, 2 H, Ar). ¹³C NMR (75 MHz CDCl₃): δ = 107.9, 128.5 (2 C), 129.9 (2 C), 133.1, 133.8, 191.7.
Compound 2j: ¹H NMR (300 MHz, CDCl₃): δ = 2.00 (s, 3 H, CH ₃), 2.04 (s, 3 H, CH ₃), 2.50 (s, 3 H, CH ₃). ¹³C NMR (75 MHz, CDCl₃): δ = 22.1, 28.9, 30.9, 95.9, 145.7, 199.4.
Compound 2m: ¹H NMR (300 MHz, CDCl₃): δ = 3.92 (s, 3 H, OCH ₃), 6.67 (s, 1 H, CHH=C), 7.55 (CHH=C). ¹³C NMR (75 MHz CDCl₃): δ = 53.7, 95.8, 139.9, 163.0.
Compound 2n: ¹H NMR (300 MHz, CDCl₃): δ = 1.16 (t, J = 7.2 Hz, 3 H, CH₂CH ₃), 1.81 (d, J = 6.6 Hz, 3 H, CH ₃CHC), 4.11 (q, J = 7.2 Hz, 2 H, CH ₂CH₃), 7.15 (q, J = 6.6 Hz, 1 H, CH₃CHC). ¹³C NMR (75 MHz CDCl₃): δ = 14.2, 22.9, 62.5, 96.9, 148.3, 162.8.