Preparation
The preparation of 1,1-bis(4-methoxyphenyl)-2-propyn-1-ol is as follows:18W % sodium acetylide in xylene/mineral oil 121.1mL (0.45mol, 1eq) was dissolved in anhydrous THF (1L) saturated with acetylene gas. After that 4,4-dimethoxybenzophenone 100g (0.41mol, 1eq) was put inside the reaction mixture under nitrogen and stirred for 24h at room temperature. The product was extracted by solvent extraction using ethyl acetate and water, organic layer was dried with MgSO4 and solid product on vacuum drier. After complete drying, the product again dissolve in ethyl acetate and poured into 1L hexane slowly under stirring which afford 8 as white color solid, yield (99g, 90%).
Synthesis
Trimethylsilylacetylene (4.5 g, 45 mmol) was dissolved in anhydrous tetrahydrofuran (150 mL) under nitrogen protection and cooled to -10°C. n-Butyllithium (1.6 M hexanes solution, 28.5 mL, 45 mmol) was slowly added, the temperature was maintained at -10°C, and the reaction mixture was stirred for 1 hour. Subsequently, a solution of anhydrous tetrahydrofuran (75 mL) of 4,4'-dimethoxybenzophenone (7.44 g, 40.8 mmol) was added dropwise at the same temperature. Stirring was continued at -10°C for 3 h. The reaction system was then slowly warmed to 0°C. A methanol (40.8 mL) solution of sodium hydroxide (2.16 g, 54 mmol) was added, followed by gradual warming of the reaction mixture to room temperature. The pH of the reaction solution was adjusted to 7 with acetic acid and the mixture was poured into water (546 mL). The aqueous phase was extracted with ethyl acetate (3 x 105 mL), the organic layers were combined and dried with anhydrous magnesium sulfate. After concentration under reduced pressure, the crude product was recrystallized by ethyl acetate/petroleum ether mixed solvent to give 7.5 g of 1,1-bis(4-methoxyphenyl)-2-propyn-1-ol (1c) as a light yellow solid in 88.4% yield.
References
[1] European Journal of Organic Chemistry, 2003, # 7, p. 1220 - 1230
[2] Angewandte Chemie - International Edition, 2014, vol. 53, # 17, p. 4341 - 4345
[3] Angew.Chem.Int.Ed., 2014, vol. 53, p. 4341 - 4345,5
[4] Tetrahedron, 2011, vol. 67, # 2, p. 401 - 407
[5] European Journal of Organic Chemistry, 2011, # 11, p. 2111 - 2119
