Reaktion #1359751

Reaktionsgleichung

chlorocyclohexane

furfural diethyl acetal

trimethyl borate

chlorocyclohexane

HCl

lithium

→

5-formyl-2-furanboronic acid

Ausbeute 77.0%

Lösungsmittel

water

THF

cyclohexane

THF

Reaktionsbedingungen

Aufarbeitung

1. 1
   workup.ADDITIONare added dropwise at the same temperature over a period of 30 minutes
2. 2
   workup.DISTILLATIONare distilled off at a maximum of 35° C. under reduced pressure
3. 3
   workup.STIRRINGthe mixture is stirred until all the product
4. 4
   Sonstigehas precipitated
5. 5
   Filtrationthe product is filtered off
6. 6
   WaschenAfter washing with a little cold water
7. 7
   Trocknena little cold acetone and drying

Vorschrift

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.

Quelle