Constant-current electrolysis, in an undivided cell, of Ph2P in the presence of a carboxylic acid in CH2C12 containing 2,6lutidinium perchlorate as the supporting electrolyte was shown to generate the corresponding acyloxyphosphonium ion, PhsP+-OCOR, which was converted in situ to esters, amides, and 8-lactams under mild conditions. Triphenylphosphine radical cation [Ph2P+*] (2), generated by one-electron oxidation of Ph2P (l), is a strong enough electrophile to react with compounds of weak nucleophilicity at ambient temperature: in the reaction of 2 with benzene, furane, and thiophene, formation of the corresponding phosphonium salts (PhsP+-Ar Y-) has been demonstrated.lr2 Thus, electrochemical oxidation of the phosphine 1 in the presence of suitable nucleophiles was expected to afford various phosphonium ions or products derived from them by simple procedures without any special or expensive additives. Quaternary phosphonium ions, either stable or transient, have been proved to occupy an important position in organophosphorus chemistry.
We have so far reported electrochemical one-step preparations of alkylaminotriphenylphosphonium perchlorate (A),3 alkoxytriphenylphosphonium perchlorate (g),4 thioalkoxytriphenylphosphonium perchlorate (c),4t5 l-alkenyltriphenylphosphonium perchlorate (D), 6 allyltriphenylphosphonium tetrafluoroborate @),7 2-oxocycloalkyltriphenylphosphonium tetrafluoroborate (p),S and dioxomethylenetriphenylphosphorane (@.g Among the products, the alkoxyphosphonium salts J1 can be used as alkylating agents,'l the phosphonium salts C were found to be convenient reagents for the preparation of unsymmetrical