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

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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 (2.5 g, 12.48 mmol) in dry CH2Cl2 (25.0 mL) was treated at 0° C. with Et3N (2.26 mL, 16.23 mmol) followed by DMAP (152 mg, 1.25 mmol) and Ms-Cl (1.16 mL, 14.98 mmol). The reaction mixture was stirred at rt for 2 h before being quenched with water (30 mL), extracted with CH2Cl2 (50 mL) and the combined org. extracts were dried over MgSO4, filtered, and the solvents were removed under reduced pressure to give 2.16 g of crude 2-(5-chloromethyl-thiophen-2-yl)-2-methyl-[1,3]dioxolane as a yellow oil. A solution of the crude material 2.11 g) in DMF (15 mL) was treated at rt with a solution of (4-nitro-2H-[1,2,3]triazole (226 mg, 2.00 mmol) in DMF (15.0 mL) pretreated for 30 min with DIPEA (2.76 mL, 16.13 mmol). The resulting mixture was stirred overnight at 50° C. Water (100 mL), followed by EA (100 mL) were added. The org. extract was washed with water (100 mL), dried over MgSO4, filtered, and the solvents were removed under reduced pressure. Purification of the residue by FC (2:1 hept-EA) gave the title compound as a white solid: TLC:rf (2:1 hept-EA)=0.17. LC-MS-conditions 02: tR=0.98 min; [M+H]+=297.08.

Provenance & Evidence