Synlett 2019; 30(11): 1308-1312
DOI: 10.1055/s-0037-1611551
© Georg Thieme Verlag Stuttgart · New York

A Simple Method for the Preparation of Stainless and Highly Pure Trichloroacetimidates

a   School of Science and Technology, Kwansei Gakuin University, 2-1, Gakuen, Sanda 669-1337, Japan   Email:
b   Department of Chemistry, Faculty of Science, Hokkaido University, West 8, North 10, Kita-ku, Sapporo 060-0810, Japan   Email:
Kentaro Murasawa
a   School of Science and Technology, Kwansei Gakuin University, 2-1, Gakuen, Sanda 669-1337, Japan   Email:
a   School of Science and Technology, Kwansei Gakuin University, 2-1, Gakuen, Sanda 669-1337, Japan   Email:
› Author Affiliations
The Ministry of Education, Culture, Sports, Science and Technology (MEXT) in Japan supported the program for the Strategic Research Foundation at Private Universities (Grant No. S1311046), and the Japan Society for the Promotion of Science (JSPS) (KAKENHI) (Grant No. JP16H01163 in Middle Molecular Strategy, and Grant No. JP16KT0061) partly supported this work.
Further Information

Publication History

Received: 10 April 2019

Accepted after revision: 29 April 2019

Publication Date:
15 May 2019 (online)


We describe a method for obtaining various allylic, benzylic, and glucosyl 2,2,2-trichloroacetimidates (TCAIs) as stainless liquids or solids at the crude stage. The general synthetic method for the preparation of TCAIs often leads to stained products, and further purification of crude TCAIs causes decomposition due to their instability. In the described method, we use a solvent that barely dissolves the reactant, providing stainless and sufficiently pure TCAIs without requiring a purification step. Furthermore, the reaction mixture is turbid at the beginning and clear at the end, allowing us to monitor the progress of the reaction visually.

Supporting Information

  • References and Notes

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  • 20 p-Methoxybenzyl 2,2,2-Trichloroacetimidate [PMB-TCAI (2)]; Typical Procedure To a suspension of PMBOH (1.00 g, 7.24 mmol) and Cl3CCN (1.15 g, 7.97 mmol) in heptane (18 mL) was added DBU (110 mg, 723 μmol) at 0 °C. After the suspension became a solution (actual reaction time = 25 min), heptane (18 mL) and saturated aq NH4Cl (18 mL) were added to the reaction mixture. The separated heptane layer was washed with saturated aq NH4Cl (18 mL) and dried over Na2SO4. Filtration of the Na2SO4 and concentration of the filtrate under reduced pressure gave PMB-TCAI (2) (2.01 g, 99%) as a colorless oil. The 1H and 13C NMR spectra of 2 were in good agreement with the literature data.22 1H NMR (400 MHz, CDCl3, 24 °C): δ = 8.36 (br s, 1 H), 7.37 (d, J = 8.7 Hz, 2 H), 6.91 (d, J = 8.7 Hz, 2 H), 5.28 (s, 2 H), 3.82 (s, 3 H). 13C NMR (101 MHz, CDCl3, 24 °C): δ = 162.8, 159.9, 129.9 (2 C), 127.7, 114.1 (2 C), 91.6, 70.8, 55.4.
  • 21 As in the syntheses of 1 and 2, the reaction mixtures for 4af, 5, 6 and 7 were initially suspensions, and then gradually became clear solutions (see pages S29–39 of the Supporting Information). All obtained products were stainless. We also confirmed that 4a, 4e, and 6 could also be preserved at –10 °C for more than one month.
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