Mild and Efficient One-Step Synthesis of Trithiocarbonates Using Minimum Amount of CS₂

Abstract

Symmetrical dialkyl trithiocarbonates were obtained from various alkyl halides with an equivalent of carbon disulfide and cesium carbonate in polar aprotic solvents, although the conventional synthesis of trithiocarbonates had required large excess amount of carbon disulfide. This reaction proceeds under ambient conditions, for example, at room temperature under an aerial ­atmosphere, without strong base nor phase-transfer catalyst.

trithiocarbonate - alkyl halides - nucleophiles - carbon disulfide - cesium carbonate

References and Notes

1 Degani I. Fochi R. Gatti A. Regondi V. Synthesis  1986,  894 ; and references therein

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9

General Procedure (1-7).
A mixture of CS₂ (5.0 mmol) and Cs₂CO₃ (5.0 mmol) in DMAc (4 mL) was stirred at 25 °C for 15 min, and then alkyl halide (5.0 mmol) in DMAc (1 mL) was added. Stirring of the reaction mixture was continued at 25 °C until the reaction was completed (monitored by ¹H NMR). The reaction was quenched by pouring into ice-water. The product was extracted with EtOAc, dried over anhyd Na₂SO₄, filtered, and evaporated to give NMR pure product. Further purification can be achieved by silica gel column chromatography eluted with hexane or hexane-CHCl₃ to afford the pure trithiocarbonate.

10

Data of Compounds 1-7.
Compound 1: mp 32-33 °C. ¹H NMR (500 MHz, CDCl₃): δ = 4.62 (s, 4 H, SCH₂), 7.24-7.34 (10 H, Ph). ¹³C NMR (500 MHz, CDCl₃): δ = 41.52 (SCH₂), 127.77 (Ph), 128.69 (Ph), 129.24 (Ph), 134.90 (Ph), 222.72 (C=S).
Compound 2: ¹H NMR (500 MHz, CDCl₃): δ = 4.04 (d, J = 9.5 Hz, 4 H, SCH₂), 5.20 (dd, J = 11.5, 2.5 Hz, 2 H, CH=CH ₂), 5.32 (dd, J = 17.5, 2.5 Hz, 2 H, CH=CH ₂), 5.83-5.92 (m, 2 H, CH=CH₂). ¹³C NMR (500 MHz, CDCl₃): δ = 39.67 (SCH₂), 119.65 (CH=CH₂), 130.93 (CH=CH₂), 222.41 (C=S).
Compound 3: ¹H NMR (500 MHz, CDCl₃): δ = 1.36 (t, J = 7.5 Hz, 6 H, CH₃), 3.37 (q, J = 7.5 Hz, 4 H, SCH₂). ¹³C NMR (500 MHz, CDCl₃): δ = 13.05 (CH₃), 31.04 (SCH₂), 224.32 (C=S).
Compound 4: ¹H NMR (500 MHz, CDCl₃): δ = 0.94 (t, J = 7.0 Hz, 6 H, CH₃), 1.44 (sext, J = 7.5 Hz, 4 H, CH ₂CH₃), 1.69 (quin, J = 7.5 Hz, 4 H, SCH₂CH ₂), 3.37 (t, J = 7.5 Hz, 4 H, SCH₂). ¹³C NMR (500 MHz, CDCl₃): δ = 13.61 (CH₃), 22.07 (CH₂CH₃), 30.06 (SCH₂ CH₂), 36.55 (SCH₂), 224.81 (C=S).
Compound 5: ¹H NMR (500 MHz, CDCl₃): δ = 0.88 (t, J = 7.5 Hz, 6 H, CH₃), 1.23-1.33 [16 H, (CH ₂)₄CH₃], 1.40 (quin, J = 7.0 Hz, 4 H, SCH₂CH₂CH ₂), 1.69 (quin, J = 7.5 Hz, 4 H, SCH₂CH ₂), 3.36 (t, J = 7.5 Hz, 4 H, SCH₂). ¹³C NMR (500 MHz, CDCl₃): δ = 14.08 (CH₃), 22.63 (CH₂CH₃), 28.01 (SCH₂CH₂ CH₂), 28.92 [CH₃CH₂CH₂ (CH₂)₂], 29.10 (SCH₂ CH₂), 31.76 (CH₃CH₂ CH₂), 36.86 (SCH₂), 224.82 (C=S).
Compound 6: mp 31-33 °C. ¹H NMR (500 MHz, CDCl₃): δ = 1.41 (d, J = 7.0 Hz, 12 H, CH₃), 4.20 (sep, J = 7.0 Hz, 2 H, SCH). ¹³C NMR (500 MHz, CDCl₃): δ = 22.02 (CH₃), 41.61 (SCH), 223.53 (C=S).
Compound 7: ¹H NMR (500 MHz, CDCl₃): δ = 1.71-1.74 (m, 6 H, CH₃), 5.28-5.33 (m, 2 H, SCH), 7.20-7.36 (10 H, Ph). ¹³C NMR (500 MHz, CDCl₃): δ = 21.26 (CH₃), 49.96 (SCH), 127.62 (Ph), 127.64 (Ph), 128.56 (Ph), 140.93 (Ph), 221.24 (C=S).

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