Ethyl chloroformate → Ethyl(1-methyl-1h-tetrazol-5-yl)acetate

To a solution of 1,5-dimethyltetrazole (10 g) in 100 mL of dry tetrahydrofuran and 20 mL of hexamethylphosphoramide at -78° C. (dry ice-acetone) under an argon atmosphere was added dropwise 50 mL (1.2 equivalent) of n-butyllithium (2.5M in hexane). The deprotonation of 1,5-dimethyltetrazole was allowed to proceed at -78° C. for 40 minutes, then at -20° C. for 30 minutes. The anion solution was rechilled to -78° C. and transferred via a cannula over a period of 45 minutes into a cold (-78° C.) solution containing 12 mL of ethyl chloroformate in 50 mL of tetrahydrofuran. The reaction mixture was diluted with aqueous 2N HCl and saturated aqueous solution of sodium chloride and then extracted with ethyl acetate. The residue from the organic extract was purified by silica gel flash chromatography. The appropriate fractions were combined and evaporated to give 4 g of product. The product was further purified by crystallization from ethyl acetate-hexanes to yield 3.52 g (21%) of the title compound; m.p.=64°-66° C.

1. waitat -20° C. for 30 minutes
2. customwas rechilled to -78° C.
3. waittransferred via a cannula over a period of 45 minutes into a cold (-78° C.) solution
4. extractionextracted with ethyl acetate
5. extractionThe residue from the organic extract
6. customwas purified by silica gel flash chromatography
7. customevaporated

ORD record

ord-802c977865e64b8eb8b0f8803340a23c

Source dataset

uspto-grants-1992_05

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05110940