Download PDF
Synlett 2010(15): 2335-2339  
DOI: 10.1055/s-0030-1258022
LETTER
© Georg Thieme Verlag Stuttgart ˙ New York

Facile Aerobic Photo-Oxidative Synthesis of Phenacyl Iodides and Bromides from Styrenes Using I2 or Aqueous HBr

Tomoya Nobuta, Shin-ichi Hirashima, Norihiro Tada, Tsuyoshi Miura, Akichika Itoh*
Gifu Pharmaceutical University 1-25-4, Daigaku-nishi, Gifu 501-1196, Japan
Fax: +81(58)2308108; e-Mail: itoha@gifu-pu.ac.jp;
Further Information

Publication History

Received 15 June 2010
Publication Date:
09 August 2010 (online)

    Permissions and Reprints All articles of this category

Abstract

We report a useful method for facile synthesis of phenacyl iodides and bromides from styrene derivatives by aerobic photo-oxidation using I2 or 48% aqueous HBr in the presence of water.

Key words

aerobic - photo-oxidation - phenacyl iodide - phenacyl bromide - styrene

21

Typical Procedure for the Synthesis of 4- tert -Butylphenacyl Iodide (2, Table 3, Entry 1)
A solution of 4-tert-butylstyrene (1, 0.3 mmol), I2 (0.18 mmol), and H2O (80 µL) in dry EtOAc (3 mL) in a Pyrex test tube, purged with an O2 balloon, was stirred and irradiated externally with four 22 W fluorescent lamps for 10 h. The reaction mixture was washed with aq Na2S2O3 and brine, and concentrated in vacuo. Purification of the crude product by PTLC (hexane-EtOAc = 5:1) provided 4-tert-butylphenacyl iodide (R f  = 0.50, 77.0 mg, 85%).
4- tert -Butylphenacyl Iodide (2) ¹H NMR (500 MHz, CDCl3): δ = 7.93 (d, J = 8.8 Hz, 2 H), 7.49 (d, J = 8.8 Hz, 2 H), 4.34 (s, 2 H), 1.35 (s, 9 H). ¹³C NMR (125 MHz, CDCl3): δ = 192.6, 157.8, 131.0, 129.1, 125.9, 35.3, 31.2, 1.9. HRMS (EI+): m/z calcd for C12H15OI [M+]: 302.0168; found: 302.0174.
2-Methylphenacyl Iodide (11) ¹H NMR (500 MHz, CDCl3): δ = 7.67 (d, J = 7.4 Hz, 1 H), 7.41 (t, J = 7.4 Hz, 1 H), 7.29-7.25 (m, 2 H), 4.33 (s, 2 H), 2.51 (s, 3 H). ¹³C NMR (125 MHz, CDCl3): δ = 195.8, 139.9, 134.4, 132.3, 128.9, 125.8, 21.5, 5.8. MS (EI+): m/z (%) = 260 [M+], 133, 119 (100), 105, 91, 65.
2-Iodo-1-(2-naphthalenyl)ethanone (23) ¹H NMR (500 MHz, CDCl3): δ = 8.51 (s, 1 H), 8.03-7.96 (m, 2 H), 7.91-7.87 (m, 2 H), 7.63-7.55 (m, 2 H), 4.48 (s, 2 H). ¹³C NMR (125 MHz, CDCl3): δ = 193.0, 135.9, 132.5, 131.1, 130.9, 129.8, 129.1, 128.9, 128.0, 127.1, 124.5, 1.9. HRMS (EI+): m/z calcd for C12H9OI [M+]: 295.9699; found: 295.9693.
2-Iodo-1-(2-pyridinyl)ethanone (26) ¹H NMR (500 MHz, CDCl3): δ = 8.70 (d, J = 4.0 Hz, 1 H), 8.10 (d, J = 6.8 Hz, 1 H), 7.89-7.86 (m, 1 H), 7.53-7.50 (m, 1 H), 4.69 (s, 2 H). ¹³C NMR (125 MHz, CDCl3): δ = 194.5, 150.8, 149.2, 137.2, 127.8, 123.0, 1.9. HRMS (EI+): m/z calcd for C7H6NOI [M+]: 246.9494; found: 246.9503.
4- tert -Butylphenacyl Bromide (3) ¹H NMR (500 MHz, CDCl3): δ = 7.92 (d, J = 8.8 Hz, 2 H), 7.50 (d, J = 8.8 Hz, 2 H), 4.43 (s, 2 H), 1.35 (s, 9 H). ¹³C NMR (125 MHz, CDCl3): δ = 191.0, 158.0, 131.4, 129.0, 126.0, 35.3, 31.3, 31.1. HRMS (EI+): m/z calcd for C12H15OBr [M+]: 254.0306; found: 254.0314.
2-Bromo-1-(2-pyridinyl)ethanone (27) ¹H NMR (500 MHz, CDCl3): δ = 8.70 (d, J = 4.6 Hz, 1 H), 8.11 (d, J = 8.0 Hz, 1 H), 7.90-7.87 (m, 1 H), 7.54-7.52 (m, 1 H), 4.87 (s, 2 H). ¹³C NMR (125 MHz, CDCl3): δ = 192.6, 151.5, 149.3, 137.3, 127.9, 122.8, 32.6. HRMS (EI+): m/z calcd for C7H6NOBr [M+]: 198.9633; found: 198.9641.
2-Bromo-1-phenyl-1-propanone (30) ¹H NMR (500 MHz, CDCl3): δ = 8.04-8.02 (m, 2 H), 7.61-7.58 (m, 1 H), 7.51-7.48 (m, 2 H), 5.30 (q, J = 6.9 Hz, 1 H), 1.91 (d, J = 6.9 Hz, 3 H). ¹³C NMR (125 MHz, CDCl3): δ = 193.4, 134.1, 133.8, 129.0, 128.9, 41.5, 20.2. MS (EI+): m/z (%) = 212 [M+], 105 (100), 77, 51.
1-Bromo-2-dodecanone (36) ¹H NMR (500 MHz, CDCl3): δ = 3.89 (s, 2 H), 2.65 (t, J = 7.5 Hz, 2 H), 1.63-1.58 (m, 2 H), 1.29-1.26 (m, 14 H), 0.88 (t, J = 6.9 Hz, 3 H). ¹³C NMR (125 MHz, CDCl3): δ = 202.4, 40.0, 34.4, 32.0, 29.6, 29.5, 29.4, 29.4, 29.1, 24.0, 22.8, 14.2. LRMS (FAB+): m/z (%) = 263 [M+ + 1], 120, 107, 89, 77, 65, 55, 41.