Nitrogen → 2-(5-Chloromethyl-thiophen-2-yl)-2-methyl-[1,3]dioxolane

Participants

Reaction Steps

In a flame dried round-bottomed flask equipped with a magnetic stir bar and under inert atmosphere (N2), a solution of [5-(2-methyl-[1,3]dioxolan-2-yl)-thiophen-2-yl]-methanol (2.00 g, 19.11 mmol) in dry CH2Cl2 (18.4 mL) was treated at 0° C. with Et3N (1.81 mL, 12.98 mmol) followed by DMAP (122 mg, 1.00 mmol) and Ms-Cl (0.93 mL, 11.98 mmol). After stirring at rt for 2 h, the reaction mixture was quenched with water (15 mL), extracted with CH2Cl2 (30 mL) and the combined org. extracts were dried over MgSO4, filtered, and the solvents were removed under reduced pressure to give crude 2-(5-chloromethyl-thiophen-2-yl)-2-methyl-[1,3]dioxolane as a yellow oil. The crude material in acetone (12 mL) was added, under inert atmosphere (N2) to a solution of 4-nitro-1H-pyrazole (1.23 g, 9.60 mmol) in acetone (12 mL). K2CO3 (3.98 g, 28.81 mmol) followed by TBA bromide (619 mg, 1.92 mmol) were added and the reaction mixture was stirred at rt overnight. Water (60 mL) and EA (80 mL) were added. The aq. layer was extracted with EA (80 mL) and the combined org. extracts were dried over MgSO4, filtered, and the solvents were removed under reduced pressure. Purification of the residue by FC (60:40 hept-EA) gave the title compound as a yellow oil. TLC: rf (60:40 hept-EA)=0.35. LC-MS-conditions 02: tR=0.96 min.

Provenance & Evidence