Reaction of 1,6-bis(diphenylphosphino)hexane with 6-bromo-1,2- naphthoquinone

The phosphonium salts with a wide range of practically useful properties are of a considerable interest [1]. Among them biologically active compounds were found capable of the preferential accumulation in mitochondria that causes inhibiting tumor cell growth owing to antioxidant effect [2], antibacterial substances [3], ionic liquids [4], phase-transfer catalysts [5] and organocatalysts [6]. Previously, we developed a new synthetic approach to phosphonium salts on the basis of the reaction of triphenylphosphine with 6-bromo-1,2-naphthoquinone I, in which the phosphorylation of naphthalene fragment occurs in the position 4 to form phosphorus ylide followed by its treating with hydrogen halides [7]. An attempt to extend this approach to 1,2-bis (diphenylphosphino)ethane led to the formation of phosphonium salts with only one phosphorus atom [8]. It may probably be due to steric hindrances to the double phosphorylation of the naphthalene ring. In this report we show that lengthening the spacer connecting two phosphine centers in 1,6-bis(diphenylphosphino) hexane II makes it possible to obtain the bis-phosphorylated derivative III in almost the quantitative yield in the reaction with quinone I. DOI: 10.1134/S1070363212050222