New P–Se compounds from the reaction of 2,4-bis(phenyl)-1,3-diselenadiphosphetane-2,4-diselenide with alkyl-diols

Reaction of alkyl-diols [HO(CH2)nOH, n=2–6, 8 and 10] with 2,4-bis(phenyl)-1,3-diselenadiphosphetane-2,4-diselenide [(PhP(μ-Se)Se)2 Woollinsʹ reagent, WR] in dry dichloromethane gave a series of bisdiselenophosphonic acids at room temperature. Treatment of the acids with butylamine in tetrahydrofuran afforded the corresponding ammonium salts 1–7 in excellent yields (91–97%). Esterification of the salts with methyl iodide led to Se,Se-dimethyl esters 8–14 in medium to excellent yields (50–86%). Alternatively, heating the toluene solution of alkyl-diols [HO(CH2)nOH, n=2–4] and WR at reflux, afforded 1,3,2-dioxaphosphorinane-2-phenyl-2-selenides 16, 18 and 20 in reasonable to good yield. Meanwhile, when 1,2-ethylene glycol was used, a heterocycle containing a selenium atom, 2,4-bisphenyl-2,4-diseleno-1,5-dioxa-3-seleno-2,4-diphosphetane 15 was formed. In the case of 1,3-propanediol or 1,4-butanediol, the heterocycles containing two neighbouring selenium atoms, 2,5-diphenyl-(1,6,3,4,2,5)-dioxadiselenadiphosphocane-2,5-disulfides 17 and 19 were obtained together with 18 and 20. Perhaps due to a steric effect, pinacol and WR in toluene at reflux gave 1,3,2-dioxaphosphorinane-2-selenide 21 as the only product. One representative X-ray crystal structure of an ammonium salt is described.