Methanol → 3-(Prop-1-ynyl)-4-propylbenzoic acid

Participants

Reaction Steps

A suspension of the product of Step A (0.36 g; 1.24 mmol) in HMDSA (2 ml) and saccharine (0.1 g) was refluxed under N2 until reaction became homogenous (˜30 min). After cooling to room temperature, the HMDSA was removed in vacuo and the residue was diluted to 4 ml with anhydrous THF. At the same time ZnCl2 (0.2 g; 1.47 mmol) was heated to ˜120° C., in separate flask, in vacuo, cooled to room temperature under N2 and diluted to 4 ml with anhydrous THF. To it 0.5 M prop-1-ynyl-magnesium bromide in THF (4.9 ml; 2.45 mmol) was added at room temperature and this was stirred for 10 min under N2. To it a solution of the protected product of Step A was added, followed by Pd(PPh3)4 (0.11 g; 0.095 mmol) and CuI (0.05 g; 0.26 mmol). After stirring for 1 h at room temperature under N2, MeOH (5 ml) was added and solvents were removed under reduced pressure. The residue was suspended in H2O (5 ml) and pH was adjusted to ˜10 with diluted NaOH. The insoluble material was removed by filtration and filtrate acidified to ˜3 with diluted HCl. The product was taken up by (2×10 ml). The organic phase was dried over anhydrous MgSO4, filtered and filtrate evaporated to dryness under reduced pressure to give the title compound (0.19 g; 76%), as creamy solid. 1H-NMR (CDCl3) 0.91-0.99 (m, 3H); 1.6-1.74 (m, 2H); 2.09 (s, 3H); 2.7-2.81 (m, 2H); 7.2-7.27 (m, 1H+CDCl3); 7.8-7.92 (m, 1H); 8.52 (m, 1H).

Provenance & Evidence