Indium(I) Bromide-Mediated Regioselective Markovnikov Hydroselenation, Diselenation and Hydration of Terminal Alkynes with Diphenyldiselenide in Aqueous Media

Abstract

The indium(III) selenolate obtained from indium(I) bromide and diphenyldiselenide promotes, alternatively, the Markovnikov hydroselenation, diselenation or hydration of terminal alkynes, depending on the experimental conditions.

Key words

indium(I) bromide - diphenyldiselenide - vinyl selenides - vinyl diselenides - hydration of alkynes - aqueous media

References

• 1 Lazell M. O’Brien P. Otway DJ. Park JH. J. Chem. Soc., Dalton Trans.  2000,  4479 
• 2a Barros OSD. Lang ES. de Oliveira CAF. Peppe C. Zeni G. Tetrahedron Lett.  2002,  43:  7921 
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• 9 The isomerization 2a → 2′a was detected before in CDCl₃ solutions. As in our case, Beletskaya and co-workers found a 2:3 (Z:E) mixture of isomers: Ananikov VP. Malyshev DA. Beletskaya IP. Aleksandrov GG. Eremenko I. J. Organomet. Chem.  2003,  679:  162 
• 12a For hydration of alkynes catalyzed by mercury salts, see: Budde WL. Dessy RE. J. Am. Chem. Soc.  1963,  85:  3964 
• 12b For hydration of alkynes catalyzed by transition metals, see: Lucey DW. Atwood JD. Organometallics  2002,  21:  2481 ; and references therein
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5

[Br₂InOH(bipy)]₂·4THF was prepared by stirring equimolar quantities of InBr and PhSeBr (1 mmol) in 20 mL of dry THF (Na/benzophenone), in a three-neck round-bottom flask, equipped with an addition funnel charged with 1 mmol of 2,2′-dipyridyl (bipy) dissolved in 5 mL of THF. As soon as the solid InBr dissolved giving a pale yellow solution, the stirring was interrupted and the bipy solution added dropwise. After addition of the bipy, H₂O (5 mmol) was added, and the flask opened to the lab atmosphere and monitored for precipitation of colorless crystals. As soon as these crystals start to deposit in the vessel, any solid impurities were filtered and the crystals allowed to grow. This treatment leaded to the deposition of [Br₂InOH(bipy)]₂·4THF (42 mg, 0.05 mmol, 10%) after 24 h at r.t. These crystals become an amorphous powder, upon drying. Analysis of the powder revealed loss of THF. Anal. Calcd for [Br₂InOH(bipy)]₂·2THF (%): Br, 30.8; In, 22.1. Found (%): Br, 30.7; In, 21.9. After removal of [Br₂InOH(bipy)]₂·4THF, the THF solution was transferred to a separation funnel and partitioned in H₂O-CH₂Cl₂. The CH₂Cl₂ solution was pumped to dryness and the residue was purified by column chromatography in silica/hexane to give PhSeSePh (47 mg, 0.15 mmol, 30%) melting at 60 °C (lit. [17] 63 °C).

6

Electronic Supplementary Information available: crystallographic data for the compound [Br₂InOH(bipy)]₂·4THF: CCDC No 279659.

7

The Markovnikov hydroselenation of the alkynes involved the following steps: aqueous EtOH (95%, 2 mL) was deoxygenated by refluxing it, under N₂ atmosphere, for 2 h in a Schlenk tube. After cooling to r.t., the tube was charged with PhSeSePh (314 mg, 1 mmol) and InBr (195 mg, 1 mmol). Continuous stirring led to the dissolution of the red solid InBr after 15-30 min. At this point, the alkyne (1 mmol) was added via syringe, and the reaction monitored by TLC. After 3 h, the reaction was quenched with H₂O and the organics extracted with CH₂Cl₂ (2 × 10 mL). The extract was dried (Na₂SO₄) and evaporated to dryness under vacuo. The oily residue was purified by columnn chromatography (silica gel/hexane) to produce the vinylic selenides 2; yields are given in Scheme [3] . Spectroscopic Data for Compounds 2a-c are as follow:
2-Phenylselenohex-1-ene (2a) [63831-76-5]: [9] yield 70%; colorless oil. ¹H NMR (CDCl₃): δ = 7.50 (m, 2 H), 7.22 (m, 3 H), 5.43 (s, 1 H), 5.08 (s, 1 H), 2.25 (t, J = 7.4 Hz, 2 H), 1.47 (quint., J = 7.3 Hz, 2 H), 1.27 (sext., J = 7.4 Hz, 2 H), 0.85 (t, J = 7.3 Hz, 3 H). ¹³C NMR and DEPT-135 (CDCl₃): δ = 143.44 (C _quat. ), 134.66 (C _ar -H), 129.11 (C _ar -H), 129.06 (C _quat. ), 127.63 (C _ar -H), 116.05 (=CH₂), 38.01 (CH₂), 30.82 (CH₂), 21.88 (CH₂), 13.79 (CH₃).
2-Phenylseleno-hept-1-ene (2b) [211189-33-2]: [18] yield 80%; colorless oil. ¹H NMR (CDCl₃): δ = 7.47 (m, 2 H), 7.22 (m, 3 H), 5.41 (s, 1 H), 5.03 (s, 1 H), 2.20 (t, J = 7.3 Hz, 2 H), 1.46 (quint., J = 7.3 Hz, 2 H), 1.20 (m, 4 H), 0.80 (t, J = 7.1 Hz, 3 H). ¹³C NMR (CDCl₃): δ = 143.52, 134.68, 129.13, 129.09, 127.67, 116.13, 38.31, 31.01, 28.37, 22.39, 14.00.
2-Phenylselenodec-1-ene (2c): colorless oil. ¹H NMR (CDCl₃): δ = 7.48 (m, 2 H), 7.22 (m, 3 H), 5.43 (s, 1 H), 5.04 (s, 1 H), 2.21 (t, J = 7.3 Hz, 2 H), 1.47 (quint., J = 7.3 Hz, 2 H), 1.20 (s, 10 H), 0.82 (t, J = 6.8 Hz, 3 H). ¹³C NMR and DEPT-135 (CDCl₃): δ = 143.50 (C _quat. ), 134.67 (C _ar -H), 129.13 (C _ar -H), 129.04 (C _quat. ), 127.65 (C _ar -H), 116.07 (=CH₂), 38.32 (CH₂), 31.83 (CH₂), 29.32 (CH₂), 29.19 (CH₂), 28.81 (CH₂), 28.67 (CH₂), 22.64 (CH₂), 14.09 (CH₃).

8

Compounds 2′a were prepared as a 2:3 mixture of stereoisomers (Z:E) following the same experimental conditions described above, [7] except the reaction time, which in this case was 48 h.
(Z,E)-2-Phenylselenohex-2-ene (2′a): [9] colorless oil. ¹H NMR (CDCl₃): δ = 7.40 (m, 2 H), 7.19 (m, 3 H), 5.91 (t, J = 7.4 Hz, 0.4 H), 5.74 (t, J = 7.0 Hz, 0.6 H), 2.19 (q, J = 7.3 Hz, 1.2 H), 2.04 (q, J = 7.3 Hz, 0.8 H), 1.95 (s, 3 H), 1.38 (sext, J = 7.4 Hz, 2 H), 0.88 (t, J = 7.3 Hz, 1.8 H), 0.87 (t, J = 7.3 Hz, 1.2 H). ¹³C NMR and DEPT-135 (CDCl₃): δ = 137.46 (C-H), 134.67 (C-H), 133.08 (C-H), 132.55 (C-H), 130.56 (C _quat ), 129.75 (C _quat ), 128.99 (C-H), 128.91 (C-H), 127.43 (C _quat ), 126.80 (C-H), 126.77 (C-H), 125.69 (C _quat. ), 33.90 (CH₂), 31.54 (CH₂), 26.47 (CH₃), 22.58 (CH₂), 22.40 (CH₂), 19.98 (CH₂), 13.78 (CH₃), 13.70 (CH₃). MS (70 eV, EI, for ⁸⁰Se): m/z (unassigned Z,E-isomers, %): 240 (24, 40) [M], 157 (17, 10), 130 (9, 64), 116 (100, 4), 55 (87, 100).

10

Heptan-2-one (3b) [110-43-0]: [19] colorless liquid. ¹H NMR (CDCl₃): δ = 2.39 (t, J = 7.5 Hz, 2 H), 2.10 (s, 3 H), 1.54 (quint., J = 7.3 Hz, 2 H), 1.26 (m, 4 H), 0.86 (t, J = 6.8 Hz, 3 H). ¹³C NMR (CDCl₃): δ = 209.16, 43.66, 31.27, 29.71, 23.47, 22.34, 13.82.
Decan-2-one (3c) [693-54-9]: [20] colorless liquid. ¹H NMR (CDCl₃): δ = 2.35 (t, J = 7.4 Hz, 2 H), 2.06 (s, 3 H), 1.50 (quint., J = 7.2 Hz, 2 H), 1.21 (br s, 10 H), 0.81 (t, J = 7.2 Hz, 3 H). ¹³C NMR and DEPT-135 (CDCl₃): δ = 208.94 (C=O), 43.62 (CH₂), 31.68 (CH₂), 29.60 (CH₃), 29.22 (CH₂), 29.04 (CH₂), 28.99 (CH₂), 23.73 (CH₂), 22.49 (CH₂), 13.89 (CH₃). MS (70 eV, EI): m/z (%) = 156 (2) [M], 138 (10), 113 (10), 99 (82), 71 (100).
5-Phenylselenopentan-2-one (6) [66241-86-9]: [2a] [21] ¹H NMR (CDCl₃): δ = 7.41 (m, 2 H), 7.18 (m, 3 H), 2.83 (t, J = 7.1 Hz, 2 H), 2.49 (t, J = 7.1 Hz, 2 H), 2.01 (s, 3 H), 1.87 (quint., J = 7.0 Hz, 2 H). ¹³C NMR (CDCl₃): δ = 207.74, 132.44, 129.84, 128.94, 126.73, 42.82, 29.80, 27.00, 23.84.

11

Nonan-2,8-dione (5a) [30502-73-9]: [22] yield 70%; colorless liquid. ¹H NMR (CDCl₃): δ = 2.36 (t, J = 7.3 Hz, 4 H), 2.06 (s, 6 H), 1.51 (quint., J = 7.5 Hz, 4 H), 1.21 (quint., J = 6.8 Hz, 2 H). ¹³C NMR (CDCl₃): δ = 208.97, 43.34, 29.85, 28.49, 23.37. MS (70 eV, EI): m/z (%) = 138 (10), 99 (61), 71 (100).
Decan-2,9-dione (5b) [16538-91-3]: [23] yield 92%; colorless solid; mp 52-53 °C. ¹H NMR (CDCl₃): δ = 2.35 (t, J = 7.4 Hz, 4 H), 2.06 (s, 6 H), 1.50 (quint., J = 6.8 Hz, 4 H), 1.20 (t, J = 7.3 Hz, 4 H). ¹³C NMR (CDCl₃): δ = 209.01, 43.57, 29.78, 28.86, 23.56. MS (70 eV, EI): m/z (%) = 170 (1) [M], 152 (19), 128 (13), 113 (47), 58 (100).
Tetradecan-2,13-dione (5c) [7029-11-0]: [22] yield 90%; colorless solid; mp 74 °C. ¹H NMR (CDCl₃): δ = 2.34 (t, J = 7.5 Hz, 4 H), 2.07 (s, 6 H), 1.49 (quint., J = 7.3 Hz, 4 H), 1.19 (br s, 12 H). ¹³C NMR (CDCl₃): δ = 209.25, 43.79, 29.80, 29.36, 29.33, 29.14, 23.86. MS (70 eV, EI):
m/z (%) = 211 (2), 169 (8), 58 (100).

15

(E)-1-Phenyl-1,2-phenylselenoethene [132330-37-1]: [13] ¹H NMR (CDCl₃): δ = 7.09-7.52 (m, 15 H), 7.02 (s, 1 H). ¹³C NMR and DEPT-135 (CDCl₃): δ = 139.51 (C _quat. ), 133.01 (CH), 132.08 (CH), 131.13 (C _quat. ), 130.62 (C _quat. ), 130.44 (C _quat. ), 129.24 (CH), 129.15 (CH), 128.59 (CH), 128.28 (CH), 128.24 (CH), 127.43 (CH), 127.40 (CH), 126.04 (CH). MS (70 eV, EI for ⁸⁰Se): m/z (%) = 416 (42) [M], 259 (56), 178 (100), 157 (71). We were not able to obtain a pure sample of the minoritary Z-isomer for NMR studies; nevertheless GC-MS analysis, 416 [M], is consistent with the proposed structure.