Triethylamine → 4,4,5,5-Tetramethyl-2-[2-(1-methyl-3-trimethylsilanyl-prop-2-ynyl)-phenyl]-[1,3,2]dioxaborolane

Participants

Reaction Conditions

Reaction Steps

A mixture of 547 mg (2.44 mmol, 0.03 eq) of Pd(OAc)2 and 2.63 grams (4.88 mmol, 0.06 eq) of bis[2-(diphenylphosphino)phenyl]ether (DPEphos) was stirred in 163 mL of dioxane in a 500 mL round bottom flask under argon at room temperature. To this heterogenous mixture was sequentially added 22.7 mL (163 mmol, 2.0 eq) of Et3N and 28.5 grams (81.3 mmol, 1.0 eq) of triflate 7. Lastly, 17.6 mL (122 mmol, 1.5 eq) of 4,4,5,5-Tetramethyl-1,3,2-dioxaborolane was added and the mixture was sparged with argon for 10 minutes. The reaction was then heated to 60° C. in a silicon oil bath and stirred until complete by 1H-NMR (aliquots removed periodically). Upon completion (˜19 hours) the mixture was cooled to room temperature and diluted with Et2O. The solution was then washed with water and the water layer was back extracted with Et2O. The combined Et2O layers were washed with brine and dried over MgSO4. Concentration and silica gel chromatography (hexane/EtOAc) gave 23.1 grams (86%) of 9 as a yellow oil, Rf 0.64 (1:1 hexane:EtOAc). 1H-NMR (500 MHz, CDCl3): 7.81 (1H, d, J=7.1 Hz), 7.75 (1H, d, J=7.8 Hz), 7.47 (1H, d, J=7.6 Hz), 7.24 (1H, d, J=7.4 Hz), 4.73 (1H, q, J=7.1 Hz), 1.45 (3H, d, J=7.1 Hz), 1.36 (6H, s), 1.35 (6H, s), 0.215 (9H, s). 13C-NMR (500 MHz, CDCl3): 150.25, 136.35, 131.64, 126.85, 125.94, 111.34, 85.66, 83.77, 31.52, 26.29, 25.17, 24.93, 0.45. IR (cm−1): 2975 (m), 2165 (m), 1598 (m), 1441 (m), 1380 (m), 1346 (s), 1249 (m), 1145 (m), 842 (s) HRMS (EI) calcd. for C19H29BO2Si: 328.2030. found: 328.2028.

Provenance & Evidence