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

ORD-Eintrag

ord-5f4844a5018640aba6ec728e23760b39

Quelldatensatz

uspto-grants-1990_01

DOI

10.6084/m9.figshare.5104873.v1

Patentnummer

US04897490