Synthesis
GENERAL METHOD: In a flame-dried reaction vial, 2-bromodibenzo[b,d]furan (1.0 mmol, 1.0 eq.) was dissolved in 2 mL of anhydrous THF. A hexane solution of n-butyllithium (1.1 mmol, 1.1 eq.) was slowly added at -78 °C and maintained at this temperature.After 30 min, this aryllithium solution was transferred to MgBr2 (1.0 mmol, 1.0 eq., reprepared from magnesium and 1,2-dibromoethane) previously suspended at -78 °C. The reaction mixture was allowed to warm naturally to room temperature over 30 min and subsequently cooled to the target temperature T. An anhydrous toluene solution (1.2 mL) of oxalidine (1.2 mmol, 1.2 eq.) was added to the reaction mixture at temperature T. The reaction was continued for a period of 30 min. The reaction was stirred continuously for 2 h at the target temperature T, after which the reaction was quenched with saturated aqueous NH4Cl solution. (The specific reaction temperature and time need to be adjusted according to the actual conditions of each substrate.)
References
[1] Patent: US2018/57444, 2018, A1. Location in patent: Paragraph 0098; 0142; 0143; 0222; 0257
[2] Journal of the American Chemical Society, 1934, vol. 56, p. 2473,2476
[3] Fortschr. Teerfarbenfabr. Verw. Industriezweige, vol. 20, p. 436,437
[4] Tetrahedron Letters, 1984, vol. 25, # 4, p. 429 - 432
[5] Chemical & Pharmaceutical Bulletin, 1986, vol. 34, # 4, p. 1524 - 1530
