New P–Se compounds from the reaction of 2,4-bis(phenyl)-1,3- diselenadiphosphetane-2,4-diselenide with alkyl-diols Guoxiong Hua, Yang Li, Alexandra M.Z. Slawin, J. Derek Woollins * School of Chemistry, University of St Andrews, Fife KY16 9ST, UK article info Article history: Received 28 January 2008 Received in revised form 14 March 2008 Accepted 3 April 2008 Available online 8 April 2008 Key words: Woollins’ reagent Alkyl-diols Ammonium salts of bisdiselenophosphonic acid Se,Se-dimethyl ester 2,4-Bisphenyl-2,4-diseleno-1,5-dioxa-3- seleno-2,4-diphosphetane 1,3,2-Dioxaphosphorinane-2-phenyl-2- selenide abstract Reaction of alkyl-diols [HO(CH 2 ) n OH, n¼2–6, 8 and 10] with 2,4-bis(phenyl)-1,3-diselenadiphosphetane- 2,4-diselenide [(PhP(m-Se)Se) 2 Woollins’ reagent, WR] in dry dichloromethane gave a series of bis- diselenophosphonic 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(CH 2 ) n OH, n¼2–4] and WR at reflux, afforded 1,3,2-dioxa- phosphorinane-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)-dioxadiselenadi- phosphocane-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. Ó 2008 Elsevier Ltd. All rights reserved. 1. Introduction Lawesson’s reagent has been widely used for the transformation of carbonyl functional groups into thiocarbonyls as well as for the synthesis of sulfur-containing heterocyclic compounds since the beginning of the last quarter of the 20th century. 1,2 Its selenium counterpart, 2,4-bis(phenyl)-1,3-diselenadiphosphetane-2,4-dis- elenide [PhP(Se)(m-Se)] 2 , Woollins’ reagent (WR) is receiving in- creasing attention due to its efficiency in selenation. For example, WR has been used to prepare a wide range of selenium-containing compounds, such as large P/Se molecular aggregates or metal complexes by nucleophilic ring-opening reactions with alkali- metal thiolates, 3 selenoamides and selenoaldehydes by simple oxygen/selenium exchange or reaction with ArCN followed by hy- drolysis as well as a variety of P–Se heterocycles by simple one-step selenation. 4 Recently, we have reported the use of WR for the syntheses of symmetrical and unsymmetrical (E)-olefins from ke- tones or aldehydes and to deoxygenate sulfoxides to give sulfides under relatively mild conditions. 5,6 Interaction of Lawesson’s reagent with aliphatic diols gives bisdithiophosphonic acids, which can be converted into the corresponding ammonium salts or used as tetradentate bisdithio- phosphonate ligands with a wide range of metal ions. 7 Lawesson’s reagent also reacts with dihydric alcohols at higher temperature leading to the formation of cyclic trithiopyrophosphonate and 1,3- dioxaphosphorinane. 8 However, similar reactions have not been tried yet for WR and complexation of phosphinodiselenoate and phosphorodiselenoate ligands has only been reported sparsely since 1964 9 whilst studies on the metal complexes of selenium compounds have been concentrated on the field of metal cluster chemistry. 10,11 Here, we report a series of new species bearing the P(Se)–Se or P]Se motif obtained by reaction of WR with alkyl-diols at both room temperature and in refluxing toluene. The new am- monium salts and methyl esters of the bisdiselenophosphonic acids, and the cyclic selenium-containing compounds gained at higher temperature provides a valuable addition to the phospho- diselenoate family. 2. Results and discussion WR was prepared as described previously in high yield (>80%) 4d and further purified by Soxhlet extraction. Cleavage of the four- membered P 2 Se 2 ring in WR by 1 equiv of diol in dichloromethane at room temperature afforded the bisdiselenophosphonic acids [quantitatively as yellow oils], which were converted into the * Corresponding author. Tel.: þ44 1334 463384. E-mail address: jdw3@st-and.ac.uk (J. Derek Woollins). Contents lists available at ScienceDirect Tetrahedron journal homepage: www.elsevier.com/locate/tet Tetrahedron 64 (2008) 5442–5448 Contents lists available at ScienceDirect Tetrahedron journal homepage: www.elsevier.com/locate/tet 0040-4020/$ – see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.tet.2008.04.017