L-(+)-Cysteine → S-(9H-Xanthen-9-yl)cysteine

Participants

Reaction Steps

A sample of 0.61 g of cysteine (5 mmole) was suspended in 100 ml of 1,2-dimethoxyethane and 2 ml of TFA. The suspension was stirred under nitrogen gas at room temperature until the solution became clear. To this clear solution was added 1 g of 9H-xanthen-9-ol (5.1 mmole) in one portion. The reaction mixture was stirred at room temperature for 30 minutes and was then neutralized to pH 7 by the addition of a saturated aqueous Na2CO3 solution. The mixture was then concentrated by rotary evaporation. The residue was diluted with 50 ml of water. The aqueous solution was treated with 10% aqueous citric acid solution to adjust the pH to 6. The mixture was stirred at room temperature for 1 hr. The resultant white solid was collected by filtration and was washed with 3×10 ml of water and 3×10 ml of ethyl acetate. The product was dried to yield 1.30 g of product.

Provenance & Evidence