ALPHA-BROMO-ALPHA-METHYL-GAMMA-BUTYROLACTONE

反应条件: temp:0.00; pressure:0.00; stir:

反应条件: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

实验步骤: To thioacetic acid S-(tetrahydro-pyran-4-yl)ester (4.25 g; 26.5 mmol) in 2-proponal (20 mL) was added KOH (36.4 mL of a 0.8 M solution in 2-propanol; 29.2 mmol). The mixture was stirred 30 minutes and α-bromo-α-methyl-γ-butyrolactone (3.00 mL; 26.5 mmol) was added dropwise. The mixture was stirred 2 hours, quenched with acetyl chloride (0.62 mL; 8.75 mmol) and the volatiles removed in vacuo. The residue was diluted with ether and filtered. Removal of the volatiles in vacuo provided a residue which was purified by silica gel chromatography using ethyl acetate and hexanes as the eluent. The product-rich fractions were concentrated in vacuo to provide 2.65 g of the desired product. 1H NMR (CDCl3) δ 4.45 (m, 1H), 4.29 (dt, 1H), 3.89 (m, 2H), 3.48 (dq, 2H), 3.20 (m, 1H), 2.33 (m, 1H), 2.21 (m, 1H), 1.95 (m, 1H), 1.88 (m, 1H), 1.86 (m, 2H), 1.65 (s, 3H). The mixture was stirred 2 hours the volatiles removed in vacuo The residue was diluted with ether filtered Removal of the volatiles in vacuo provided a residue which was purified by silica gel chromatography The product-rich fractions were concentrated in vacuo