Hydrochloric Acid → 5-Formylfuran-2-boronic acid

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

A mixture of 20.88 g of chlorocyclohexane (0.176 mol) and 27.2 g of furfural diethyl acetal (0.16 mol) is added dropwise to a suspension of 2.35 g of lithium granules (0.34 mol) in 300 g of THF at −65° C., with an addition time of 2 hours being selected. After a conversion of the chlorocyclohexane of >97% determined by GC (total of 10 h), 18.3 g of trimethyl borate (0.176 mol) are added dropwise at the same temperature over a period of 30 minutes. After stirring for another 30 minutes at −65° C., the reaction mixture is poured into 120 g of water, the pH is adjusted to 6.3 by means of 37% HCl, and THF and cyclohexane are distilled off at a maximum of 35° C. under reduced pressure. The pH is subsequently adjusted to 1.5, the mixture is stirred until all the product has precipitated and the product is filtered off. After washing with a little cold water and a little cold acetone and drying, 17.2 g of 5-formyl-2-furanboronic acid (0.123 mol, 77%) are obtained in the form of a fine beige powders, HPLC purity >99% a/a.

Herkunft & Nachweise