Trimethylorthoformate

Example 7

Synthesis of 4-(2,2,3,3,4,4,5,5,5-nonafluoropentyl)-2-(2,2,2-trifluoroethoxy)-1,3-dioxolane. 1H, 1H, 2H, 3H, 3H-perfluoroheptane-1,2-diol (25 g, 85 mmol, 1 eq., SynQuest Laboratories, Inc. (Alachua, Fla.)) was dissolved in 250 mL of cyclohexanes (Aldrich). Trimethylorthoformate (18 g, 170 mmol, 2.0 eq., Aldrich) was added to the flask along with a catalytic amount of Amberlyst 15 (H form, Aldrich) and a Teflon coated magnetic stirbar. The flask was fitted with a Dean-Stark distillation head. The reaction was slowly heated to reflux and the methanol was removed by azeotropic distillation at a boiling point of 65° C. After 4 hours, the reaction was deemed complete by the lack of further distillation of trifluoroethanol azeotrope and the flask cooled to room temperature. The Amberlyst resin was removed by filtration and the filtrate concentrated at reduced pressure on a rotary evaporator. The residual mixture was purified by fractional distillation under reduced pressure (b.p.=105-110° C. at 10 mmHg), providing the title compound in 39% isolated yield. The product was verified by characteristic peaks in the ¹H NMR and by molecular ion in ESI/TOF mass spectroscopy (M+1, 405.0 m/z).

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Example 9

Synthesis of 2-methoxy-4,5-bis(2,2,3,3,4,4,5,5,5-nonafluoropentyl)-1,3-dioxolane. 1,1,1,2,2,3,3,4,4,9,9,10,10,11,11,12,12,12-Octadecafluoro-6,7-dodecanediol was prepared by the method described by Laurent, P. et al (Journal of Fluorine Chemistry, 62(2-3), 161-71; 1993). The diol (12 g, 22.8 mmol) was dissolved in 120 mL of cyclohexanes (Aldrich). Trimethylorthoformate (4.8 g, 45.6 mmol, 2.0 eq., Aldrich) was added to the flask along with a catalytic amount of Amberlyst 15 (H form, Aldrich) and a Teflon coated magnetic stirbar. The flask was fitted with a Dean-Stark distillation head. The reaction was slowly heated to reflux and the methanol was removed by azeotropic distillation at a boiling point of 45° C. After 4 hours, the reaction was deemed complete by the lack of further distillation of methanol azeotrope and the flask cooled to room temperature. The Amberlyst resin was removed by filtration and the filtrate concentrated at reduced pressure on a rotary evaporator. The residual mixture was purified by fractional distillation under reduced pressure (b.p.=162-173° C. at 10 mmHg), providing the title compound in 52% isolated yield. The product was verified by characteristic peaks in the ¹H NMR and by molecular ion in ESI/TOF mass spectroscopy (M+1, 569.1 m/z).

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Example 3

Synthesis of 2-methoxy-4-(3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl)-1,3-dioxolane. 5,5,6,6,7,7,8,8,9,9,10,10,10-tridecafluorodecane-1,2-diol (25 g, 61 mmol, 1 eq., Shanghai Chemhere Co., Ltd.) was dissolved in 300 mL of a 90/10 (vol/vol) mixture of cyclohexanes/trifluorotoluene (Aldrich) at a concentration of 2 M. Trimethylorthoformate (9 g, 85 mmol, 1.4 eq., Aldrich) was added to the flask along with a catalytic amount of Amberlyst 15 (H form, Aldrich) and a Teflon coated magnetic stirbar. The flask was fitted with a Dean-Stark distillation head. The reaction was slowly heated to reflux and the methanol was removed by azeotropic distillation at a boiling point of 45° C. After 4 hours, the reaction was deemed complete by the lack of further distillation of methanol azeotrope and the flask was cooled to room temperature. The Amberlyst resin was removed by filtration and the filtrate concentrated at reduced pressure on a rotary evaporator. The residual was purified by fractional distillation under reduced pressure (b.p.=120-130° C. at 10 mmHg), providing the title compound in 64% isolated yield. The product was verified by characteristic peaks in the ¹H NMR and by molecular ion in ESI/TOF mass spectroscopy (M+1, 451.1 m/z).

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Example 19

Synthesis of 2-methoxy-4-((phenyldisulfanyl)methyl)-1,3-dioxolane. 3-(phenyldisulfanyl)propane-1,2-diol was prepared by the method described by Hunter R. et al (Journal of Organic Chemistry, 71, 8268-8271; 2006). The diol (102 mg, 0.47 mmol) was dissolved in cyclohexane (Aldrich) at a concentration of 0.1M in a round bottom flask containing a Teflon coated magnetic stirbar. Trimethyl orthoformate (1.5 eq, Aldrich) and p-toluenesulfonic acid (Aldrich) were added to the round bottom flask and the flask was fitted with a Dean-Stark distillation head. The reaction was slowly heated to reflux and the methanol was removed by azeotropic distillation at a boiling point of 45° C. After 3 hours, the reaction was complete and the flask cooled to room temperature, followed by concentration at reduced pressure on a rotary evaporator. The product was purified by silica gel column chromatography, eluting with a gradient of hexane:ethyl acetate (starting from hexane). The title compound was isolated in 68% yield. The product was verified by characteristic peaks in the 1H and 13C NMR and by molecular ion in positive mode ESI/TOF mass spectroscopy ([M-OMe]⁺, 227.0 m/z).

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