Synlett 2019; 30(06): 694-698
DOI: 10.1055/s-0037-1611731
letter
© Georg Thieme Verlag Stuttgart · New York

Solvent-Free Synthesis of α-Amino Ketones from α-Hydroxyl Ketones via A Novel Tandem Reaction Sequence Based on Heyns Rearrangement

Ling-yu Li
a   College of Materials and Chemistry & Chemical Engineering, Chengdu University of Technology, Dongsanlu, Erxianqiao, Chengdu, Sichuan 610059, P. R. of China   Email: qinglezeng@hotmail.com
,
a   College of Materials and Chemistry & Chemical Engineering, Chengdu University of Technology, Dongsanlu, Erxianqiao, Chengdu, Sichuan 610059, P. R. of China   Email: qinglezeng@hotmail.com
,
b   Natural Products Research Center, Chengdu Institute of Biology, Chinese Academy of Science, Chengdu, Sichuan 610041, P. R. of China   Email: ligx@cib.ac.cn   Email: tangzhuo@cib.ac.cn
,
Zhuo Tang  *
b   Natural Products Research Center, Chengdu Institute of Biology, Chinese Academy of Science, Chengdu, Sichuan 610041, P. R. of China   Email: ligx@cib.ac.cn   Email: tangzhuo@cib.ac.cn
› Author Affiliations
This work was supported financially by the Natural Science Foundation of Sichuan province, China (2017JY0055) and the Youth Innovation Promotion Association CAS (2018402).
Further Information

Publication History

Received: 03 January 2019

Accepted after revision: 28 February 2019

Publication Date:
19 February 2019 (online)


Abstract

Heyns rearrangement have been famous for carbohydrate chemists for several decades. However, this reaction was underrated as a useful method for synthetic chemists due to preparative shortcomings. Herein we developed an efficient method for the synthesis of pharmaceutically important α-amino ketones from readily available α-hydroxy ketones and secondary amines through a tandem reaction sequence based on Heyns rearrangement. The reaction smoothly proceeded by using catalytic PTSA as catalyst without solvent. Primary and secondary α-hydroxy ketones were readily used and regioselectively afforded the correspondingly α-amino ketones with moderate yield.

Supporting Information

 
  • References and Notes

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  • 15 Preparation of 2-[Methyl(phenyl)amino]-1-phenylethan-1-one (3j) – General Procedure 2-Hydroxyacetophenone (0.1 mmol) and morpholine (0.1 mmol) were added in a reaction vessel followed by catalytic PTSA (0.005 mmol). The reaction mixture was stirred under nitrogen atmosphere overnight at 50 ℃. After full conversion of the starting material, the reaction mixture was cooled down to room temperature and purified by silica gel flash column directly (eluent: petroleum ether/ethyl acetate = 3:1); colorless oil, 14.2 mg (63%). 1H NMR (400 MHz, CDCl3): δ = 8.11–7.96 (m, 2 H), 7.64 (t, J = 7.4 Hz, 1 H), 7.52 (t, J = 7.6 Hz, 2 H), 7.24 (dd, J = 8.7, 7.4 Hz, 2 H), 6.83–6.59 (m, 3 H), 4.81 (s, 2 H), 3.13 (s, 3 H). 13C NMR (101 MHz, CDCl3): δ = 196.48 (s), 149.20 (s), 135.46 (s), 133.55 (s), 129.21 (s), 128.82 (s), 127.81 (s), 117.12 (s), 112.28 (s), 77.34 (s), 77.03 (s), 76.71 (s), 58.99 (s), 39.58 (s). HRMS (ESI): C15H15NO neutral mass: 225.11536; observed [M + H]+: 226.12296.
  • 16 Preparation of 2-(Indolin-1-yl)-1-phenylpropan-1-one (4i) The reaction executed with general procedure, 24 h at 80 °C; brown oil, 11.3 mg (45%). 1H NMR (400 MHz, CDCl3): δ = 8.12–8.04 (m, 2 H), 7.64–7.53 (m, 1 H), 7.53–7.39 (m, 2 H), 7.19–7.07 (m, 2 H), 6.70 (dd, J = 10.7, 3.9 Hz, 1 H), 6.58 (d, J = 7.7 Hz, 1 H), 5.22–5.10 (m, 1 H), 3.47 (dd, J = 18.2, 9.5 Hz, 1 H), 3.32 (td, J = 8.9, 5.2 Hz, 1 H), 3.01–2.85 (m, 2 H), 1.40 (t, J = 7.4 Hz, 3 H). 13C NMR (101 MHz, CDCl3): δ = 199.23 (s), 150.03 (s), 135.78 (s), 133.24 (s), 130.16 (s), 128.54 (s), 127.38 (s), 124.71 (s), 117.80 (s), 106.31 (s), 55.04 (s), 47.65 (s), 28.26 (s), 10.15 (s). HRMS (ESI): C17H17NO2 neutral mass: 251.13101; observed [M + H]+: 252.13811.
  • 17 Preparation of 1-(4-Bromophenyl)-2-morpholinobutan-1-one (4n) The reaction executed with the general procedure; yellow oil, 17.1 mg (55%). 1H NMR (400 MHz, CDCl3): δ = 8.07–7.86 (m, 2 H), 7.75–7.56 (m, 2 H), 3.81 (dd, J = 9.3, 4.7 Hz, 1 H), 3.68 (dd, J = 10.8, 6.2 Hz, 4 H), 2.75–2.63 (m, 2 H), 2.62–2.48 (m, 2 H), 1.97–1.70 (m, 2 H), 0.92–0.84 (m, 4 H). 13C NMR (101 MHz, CDCl3): δ = 198.59 (s), 131.82 (s), 130.21 (s), 77.33 (s), 77.02 (s), 76.70 (s), 70.99 (s), 67.31 (s), 50.28 (s), 19.06 (s), 10.97 (s), 1.02 (s). HRMS (ESI): C14H18BrNO2 neutral mass: 311.05209; observed [M + H]+: 312.05453.
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