The general procedure for the synthesis of 2-chloro-5-iodothiophene from 2-iodothiophene is as follows:
Example 1: Synthesis of 1-(5-chlorothiophen-2-yl)-2-(2,4-difluorophenyl)-1,1-difluoro-3-(1H-tetrazol-1-yl)propan-2-ol
1. 2-Iodothiophene (2.5 g, 11.9 mmol) was dissolved in hexane (25 mL) and stirred until completely dissolved.
2. N-chlorosuccinimide (NCS; 1.58 g, 11.9 mmol) was added to the above solution.
3. A catalytic amount of perchloric acid (HClO4) was added and the reaction was stirred continuously for 24 hours (h) at room temperature (RT).
4. Upon completion of the reaction, the reaction mixture was filtered and the filtrate was collected.
5. The filtrate was washed sequentially with water (H2O) and brine and then dried with anhydrous sodium sulfate (Na2SO4).
6. The dried filtrate was concentrated under vacuum to give 2-chloro-5-iodothiophene in liquid form (1.7 g, 6.9 mmol, 58% yield).
Product characterization: 1H NMR (200 MHz, CDCl3): δ 7.18 (d, J = 4.2 Hz, 1H), 6.69 (d, J = 4.2 Hz, 1H).
