Iodine → HCID 14906788, compound

Participants

Reaction Conditions

Reaction Steps

db) 3.38 g (10 mmol) of (3,4-dimethoxyphenyl)diphenylphosphine oxide and 50 ml of dry tetrahydrofuran were placed in a 0.3 l four-necked sulphonation flask provided with a stirrer, thermometer, dropping funnel and argon gasification. In a separate Schlenk tube 8.0 ml of 1.6N butyllithium solution in hexane (12.8 mmol) were added dropwise under argon and while stirring at -78° C. to a solution of 1.57 g (15.5 mmol) of diisopropylamine in 10 ml of tetrahydrofuran and the solution was stirred at 0° C. for a further 10 minutes. The thus-prepared lithium diisopropylamide solution was then transferred into the dropping funnel of the reaction apparatus and then added dropwise at about -75° C. to the (3,4-dimethoxyphenyl)-diphenylphosphine oxide solution. The resulting pink suspension was stirred at -78° C. for a further 2 hours. Then, it was treated dropwise at <-70° C. with a solution of 3.3 g (13 mmol) of iodine in 20 ml of tetrahydrofuran. Towards the end of the addition there formed a viscous paste which was difficult to stir and which again dissolved when subsequently left to warm to room temperature. The reaction solution was washed 3 times with 20 ml of saturated Na2S2O3 solution each time and once with saturated NaCl solution, dried over Na2SO4, filtered and evaporated. The residue (5 g) was chromatographed on 200 g of silica gel with ethyl acetate and the resulting product was recrystallized from tert.-butyl methyl ether. There were obtained 3.8 g of (2-iodo-3,4-dimethoxyphenyl)-diphenylphosphine oxide as a light beige crystallizate : m.p. 178.5°-179.5° C.

Provenance & Evidence