Novel and Efficient Synthesis of 1-Iodoalkynes

Abstract

Treatment of terminal alkynes with (diacetoxyiodo)benzene, potassium iodide, and copper(I) iodide afforded 1-iodo­alkynes in good to excellent yields under mild conditions.

Key words

potassium iodide - copper(I) iodide - 1-iodoalkynes - ­(diacetoxyiodo)benzene

References and Notes

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7

General Procedure for the Iodination of Terminal Alkynes To MeCN (3 mL), alkyne 1 (0.5 mmol), DIB (0.5 mmol), Et₃N (1.0 mmol), KI (1.0 mmol), and CuI (5.0 mol%) were added. The mixture was stirred at r.t. for 0.3-0.5 h and then separated on a silica gel plate using PE as eluent, 1-iodo-alkyne 2 was afforded in good to excellent yield.
Compound 2a: Oil. ¹H NMR (400 MHz, CDCl₃): δ = 7.44-7.42 (m, 2 H), 7.32-7.29 (m, 3 H). ¹³C NMR (100 MHz, CDCl₃): δ = 132.3, 128.8, 128.2, 123.4, 94.1, 6.1. IR (film): ν = 2175, 755, 690 cm^-1. MS (EI): m/z (%) = 228 (100) [M⁺].
Compound 2b: Oil. ¹H NMR (400 MHz, CDCl₃): δ = 7.32 (d, J = 8.4 Hz, 2 H), 7.11 (d, J = 8.0 Hz, 2 H), 2.35 (s, 3 H). ¹³C NMR (100 MHz, CDCl₃): δ = 139.0, 132.2, 129.0, 120.3, 94.2, 21.5, 4.9. IR (film): ν = 2170, 818 cm^-1. MS (EI): m/z (%) = 242 (100) [M⁺].
Compound 2c: Oil. ¹H NMR (400 MHz, CDCl₃): δ = 7.35 (d, J = 8.0 Hz, 2 H), 7.14 (d, J = 8.0 Hz, 2 H), 2.64 (q, J = 7.6 Hz, 2 H), 1.23 (t, J = 7.2 Hz, 3 H). ¹³C NMR (100 MHz, CDCl₃): δ = 145.5, 132.5, 128.1, 120.8, 94.5, 29.1, 15.6, 5.3. IR (film): ν = 2174, 822 cm^-1. MS (EI): m/z (%) = 256 (64) [M⁺] , 241 (100). HRMS: m/z calcd for C₁₀H₉I: 255.9749; found: 255.9742.
Compound 2d: Oil. ¹H NMR (400 MHz, CDCl₃): δ = 7.34 (d, J = 8.0 Hz, 2 H), 7.11 (d, J = 7.6 Hz, 2 H), 2.58 (t, J = 7.2 Hz, 2 H), 1.65-1.57 (m, 2 H), 0.92 (t, J = 7.2 Hz, 3 H). ¹³C NMR (100 MHz, CDCl₃): δ = 143.8, 132.1, 128.4, 120.6, 94.3, 37.9, 24.3, 13.7, 4.9. IR (film): ν = 2175, 817 cm^-1. MS (EI): m/z (%) = 270 (62) [M⁺], 241 (100). HRMS: m/z calcd for C₁₁H₁₁I: 269.9905; found: 269.9889.
Compound 2e: Mp 61-62 °C (decomp.). ¹H NMR (400 MHz, CDCl₃): δ = 7.37 (d, J = 8.8 Hz, 2 H), 6.83 (d, J = 7.6 Hz, 2 H), 3.81 (s, 3 H). ¹³C NMR (100 MHz, CDCl₃): δ = 160.0, 133.8, 115.6, 113.8, 94.0, 55.3, 3.7. IR (KBr): ν = 2162, 824 cm^-1. MS (EI): m/z (%) = 258 (100) [M⁺].
Compound 2f: Mp 92-94 °C (decomp.). ¹H NMR (400 MHz, CDCl₃): δ = 7.45 (d, J = 8.4 Hz, 2 H), 7.29 (d, J = 8.4 Hz, 2 H). ¹³C NMR (100 MHz, CDCl₃): δ = 133.7, 131.5, 123.1, 122.2, 93.0, 8.0. IR (KBr): ν = 2163, 820, 522 cm^-1. MS (EI): m/z (%) = 306 (100) [M⁺ - 1], 308 (83) [M⁺ + 1].
Compound 2g: Mp 180-181 °C (decomp.). ¹H NMR (400 MHz, CDCl₃): δ = 8.19 (d, J = 8.8 Hz, 2 H), 7.56 (d, J = 8.8 Hz, 2 H). ¹³C NMR (100 MHz, CDCl₃): δ = 151.7, 136.8, 125.1, 121.2, 92.8, 8.7. IR (KBr): ν = 2169, 1510, 1344, 851 cm^-1. MS (EI): m/z (%) = 273 (100) [M⁺].
Compound 2h: Mp 64-65 °C. ¹H NMR (400 MHz, CDCl₃): δ = 7.64 (d, J = 8.0 Hz, 1 H), 7.58 (d, J = 7.6 Hz, 1 H), 7.49 (dd, J = 7.6, 7.2 Hz, 1 H), 7.41 (dd, J = 8.0, 7.6 Hz, 1 H). ¹³C NMR (100 MHz, CDCl₃): δ = 134.9, 131.3, 128.5, 125.8, 124.6, 121.9, 121.4, 89.8, 13.2. IR (KBr): ν = 2170, 752, 735, cm^-1. MS (EI): m/z (%) = 296 (100) [M⁺]. Anal. Calcd for C₉H₄F₃I: C, 36.50; H, 1.35. Found: C, 36.38; H, 1.33.
Compound 2i: Oil. ¹H NMR (400 MHz, CDCl₃): δ = 2.36 (t, J = 7.2 Hz, 2 H), 1.53-1.37 (m, 4 H), 0.91 (t, J = 7.6 Hz, 3 H). ¹³C NMR (100 MHz, CDCl₃): δ = 94.3, 32.1, 23.4, 21.4, 15.3, 7.9. IR (film): ν = 2190 cm^-1. MS (EI): m/z (%) = 208 (100) [M⁺].
Compound 2j: Oil. ¹H NMR (400 MHz, CDCl₃): δ = 2.35 (t, J = 7.2 Hz, 2 H), 1.53-1.47 (m, 2 H), 1.38-1.30 (m, 4 H), 0.89 (t, J = 7.2 Hz, 3 H). ¹³C NMR (100 MHz, CDCl₃): δ = 94.1, 31.0, 28.1, 22.0, 20.8, 14.0, 7.6. IR (film): ν = 2185 cm^-1. MS (EI): m/z (%) = 222 (100) [M⁺].