References and Notes
1a
Momiyama N.
Yamamoto H.
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1b
Momiyama N.
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2a
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2b
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2c
Momiyama N.
Yamamoto H.
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2d
Momiyama N.
Torii H.
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Yamamoto H.
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2e
Momiyama N.
Yamamoto H.
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For a representative paper, see:
3a
Zhong G.
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3b
Brown SP.
Brochu MP.
Sinz CJ.
MacMillan DWC.
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3c
Hayashi Y.
Yamaguchi J.
Hibino K.
Shoji M.
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3d
Bøgevig A.
Sundén H.
Córdova A.
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3e
Hayashi Y.
Yamaguchi J.
Sumiya T.
Shoji M.
Angew. Chem. Int. Ed.
2004,
43:
1112
For a review, see:
4a
Merino P.
Tejero T.
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4b
Janey JM.
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4c
Yamamoto H.
Momiyama N.
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5
α-Hydroxycyclohexanone (
2a).
A flame-dried test tube equipped with magnetic stirring bar and a septum was charged with aminooxy ketone 1a (1.0 mmol) and dissolved in anhyd MeOH (5 mL) and THF (5 mL). CuSO4 (0.3 mmol) was added with one portion at 0 °C. Once all of compound 1a was consumed, the reaction was quenched with pH 7.0 phosphate buffer (5 mL). The aqueous layer was then extracted four times with 5 mL of CHCl3. The combined organic layers were then dried over Na2SO4, filtered and concentrated. The crude product was purified by flash chromatography on silica gel with hexanes-EtOAc as eluent. The cyclohexanone 2a was obtained as a whitish yellow liquid. TLC: R
f
= 0.16 (3:1 hexane-EtOAc). 1H NMR (400 MHz, CDCl3): δ = 4.11 (m, 1 H, CH), 3.68 (d, 1 H, J = 3.6 Hz), 2.44-2.58 (m, 3 H, CH
2), 2.05-2.15 (m, 1 H, CH
2), 1.88-1.95 (m, 1 H, CH
2), 1.40-1.70 (m, 3 H, CH
2). 13C NMR (100 MHz, CDCl3): δ = 211.4, 75.3, 39.42, 36.63, 27.50, 23.30.
6
2-(Phenylamino)cyclohex-2-enone (
3a).
Purification by flash column chromatography with elution by hexane-EtOAc (20:1) provided a yellowish solid. TLC: R
f
= 0.49 (3:1 hexane-EtOAc). 1H NMR (400 MHz, CDCl3): δ = 7.25 (t, 2 H, J = 8.0 Hz, ArH), 7.20 (d, 2 H, J = 8.0 Hz, ArH), 6.90 (t, 1 H, J = 8.0 Hz, ArH), 6.41 (t, 1 H, J = 4.0 Hz, CH), 6.36 (s, 1 H, NH), 2.55 (t, 2 H, CH
2), 2.43 (dd, 2 H, CH
2), 2.03-1.96 (m, 2 H, CH
2). 13C NMR (125 MHz, CDCl3): δ = 195.5, 141.8, 136.1, 129.1 (2 C), 120.9, 118.5 (2 C), 116.3, 37.6, 24.5, 22.8.
7
5,5-Dimethyl-2-(phenylamino)cyclohex-2-enone (
3b).
Purification by flash column chromatography with elution by hexane-EtOAc (20:1) provided a yellowish solid. TLC: R
f
= 0.49 (5:1 hexane-EtOAc). 1H NMR (400 MHz, CDCl3): δ = 7.26 (t, 2 H, J = 8.0 Hz, ArH), 7.04 (d, 2 H, J = 8.0 Hz, ArH), 6.90 (t, 1 H, J = 8.0 Hz, ArH), 6.33
(s, 1 H, NH), 6.27 (t, 1 H, J = 4.8 Hz, CH), 2.41 (s, 2 H, CH
2), 2.35 (d, 2 H, CH
2), 1.11 (s, 6 H, CH
3). 13C NMR (125 MHz, CDCl3): δ = 195.6, 142.0, 135.4, 129.2 (2 C), 120.9, 118.5 (2 C), 113.7, 51.0, 38.5, 34.0, 28.2 (2 C).
4,4-Dimethyl-2-(phenylamino)cyclohex-2-enone (
4b).
Purification by flash column chromatography with elution by hexane-EtOAc (20:1) provided a yellowish solid. TLC: R
f
= 0.45 (5:1 hexane-EtOAc). 1H NMR (400 MHz, CDCl3): δ = 7.26 (t, 2 H, J = 8.0 Hz, ArH), 7.02 (d, 2 H, J = 8.0 Hz, ArH), 6.88 (t, 1 H, J = 8.0 Hz, ArH), 6.24 (s, 1 H, NH), 6.14 (s, 1 H, CH), 2.61 (t, 2 H, CH
2), 1.88 (t, 2 H, CH
2), 1.20 (s, 6 H, CH
3). 13C NMR (125 MHz, CDCl3): δ = 195.2, 141.8, 133.7, 129.2 (2 C), 126.5, 120.9, 118.5 (2 C), 35.7, 33.7, 32.4, 29.0 (2 C).
8 A flame-dried test tube equipped with a magnetic stirring bar and an aluminum cap was charged with aminooxy ketone 1b (0.2 mmol) and EuCl3 (10 mol%), and dissolved in anhyd EtOH (1 mL). The reaction was heated at 105 °C in a microwave oven for 5 min. The reaction mixture was quenched by brine (5 mL) and the aqueous layer was extracted with CHCl3 (2 × 10 mL). The combined organic extracts were washed with brine, dried over Na2SO4 and concentrated under reduced pressure after filtration. The residual crude product was purified by flash column chromatography on a silica gel using a mixture of EtOAc and hexane (1:20) as the eluant to give the product.
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