2H-1-Benzopyran, 3,4-dihydro-7-nitro- synthesis

Yield:50386-70-4 74%

Reaction Conditions:

with isopentyl nitrite in tetrahydrofuran at 0; for 3.25 h;Reflux;

Steps:

4.1.7.8. 6-Nitro-2,3-dihydrobenzofuran (15) and 7-nitrochroman (16).

Isoamylnitrite (3 equiv) was added dropwise to a solution of 13 or 14(1 equiv) in anhydrous THF at 0°C. The reaction mixture was stirred at 0°C for 15 min and then refluxed for 3 h. The solution was cooled to room temperature, water (50 mL) was added, and the solution was extracted with ethyl acetate (350 mL). The organic layer was washed with brine, dried over MgSO₄, then evaporated and purified by column chromatography with a gradient eluent of EA/n-hexane (2-8%) to give 15 (70%) as a yellow solid or 16 (74%) as a yellow solid.

References:

Lee, Jeewoo;Tran, Phuong-Thao;Hoang, Van-Hai;Thorat, Shivaji A.;Kim, Sung Eun;Ann, Jihyae;Chang, Yu Jin;Nam, Dong Woo;Song, Hyundong;Mook-Jung, Inhee;Lee, Jiyoun [Bioorganic and Medicinal Chemistry,2013,vol. 21,# 13,p. 3821 - 3830]