Phosphonyl, Phosphonothioyl, Phosphonodithioyl, and Phosphonotrithioyl Radicals: Generation and Study of Their Addition onto Alkenes† Chrystel Lopin,‡ Ge´raldine Gouhier, Arnaud Gautier, and Serge R. Piettre* Laboratoire des Fonctions Azote´ es et Oxyge´ ne´ es Complexes, UMR CNRS 6014, IRCOF-Universite´ de Rouen, Rue Tesnie` res, F-76821 Mont Saint Aignan, France
[email protected] Received June 11, 2003
The treatment of benzyl dialkyl phosphites and dithiophosphites with benzeneselanyl chloride generates an Arbuzov-type transformation leading to the dialkyl selenophosphates 19a and 19b and to selenophosphorodithioates 21a and 21b. Interaction of these substrates with Lawesson’s reagent yields the corresponding selenophosphorothioates 20a and 20b and the selenophosphorotrithioates 22a and 22b. When treated with a radical initiator in the presence of a hydrogen donor and an alkene, all eight phosphorus(V) precursors undergo homolytic cleavage of the P-Se bond to generate the phosphonyl, phosphonothioyl, phosphonodithioyl, or phosphonotrithioyl radicals. Most of these are shown to add onto electron-rich and electron-poor alkenes to deliver the expected adducts in fair to excellent yields. Cyclic precursor 19b displays peculiar behavior and, under the reaction conditions, produces only the corresponding cyclic phosphite. Application of this radical chain process is carried out on furanosyl 3-exo-methylene derivative 37 to diastereoselectively furnish five new 3-phosphonomethyl-, 3-phosphonothiomethyl-, and 3-phosphonodithiomethyl-3deoxofuranoses 38a-c and 38f,g. The possibility of conducting tandem processes is also discussed through experiments involving (1R)-(+)-R-pinene (39) and diallylamine 41. Introduction Phosphonates 2 have attracted much attention during the past decades because of their similarities with the phosphate functional group 1 (Figure 1).1 The central role played by the latter in numerous biological processes and its position as a crucial constituent of many major biomolecules have resulted in the development of various synthetic methodologies designed at producing 2 as mimics of the parent phosphate. The replacement of one or more oxygen atom(s) in phosphonates by sulfur generates phosphonothioates, phosphonodithioates, or phosphonotrithioates (3, 4, or 5, respectively). The large range of organophosphorus compounds containing sulfur have found widespread use as pesticides, in petroleum technology, and in metal ore extraction techniques.2 The reported preparations of species 3-5 enter in two categories: the first ones rely on phosphoruscarbon bond formation, while the others exploit modifications at phosphorus in phosphorus-carbon-bonded compounds.3 The approach relying on the addition of phosphorus-centered radicals onto alkenes was first introduced in the early 1950s on substrates devoid of sulfur and, more recently, was extended to substrates †
Taken from the Ph.D. Thesis of C.L. Present adress: Institut de Chimie Organique et Analytique, UMR CNRS 6005, Universite´ d’Orle´ans-UFR de Sciences, Rue de ChartresBP 6759, F-45067 Orle´ans Cedex 2, France. (1) Hartley, F. R., Ed. The Chemistry of Organophosphorus Compounds, Vol. 4, Ter- and Quinque-valent Phosphorus Acids and Their Derivatives; John Wiley & Sons: Chichester, 1996. ‡
FIGURE 1. Structures of phosphates 1, phosphonates 2, phosphonothioates 3, phosphonodithioates 4, and phosphonotrithioates 5.
encompassing single or double phosphorus-sulfur bond(s). Thus, several reports have since then demonstrated the efficiency of the method, when applied to O,Odialkylphophites 6 or O,O-dialkylthiophosphites 7; O,Odialkylphosphonates and phosphonothioates are generally obtained in good to excellent yields (Scheme 1).4 (2) See, for instance: (a) Shell, D. C.; Hayward, E. C. U.S. Patent 4,024,049 (19770517), 1977. (b) Ukeles, S. D.; Ben-Yoseph, E.; Finkelstein, N. P. Eur. Patent 89-302,625 (19890316), 1989. (c) Kazama, H.; Matsuoka, S. Jpn. Patent 04,330,083 (92,330,383), 1992. (d) Kazama, H.; Matsuoka, S. Jpn. Patent 05,39,296 (93 39,296), 1993. (e) Nakanishi, H.; Kuribayashi, T. Jpn. Patent 05 09,490 (93 09,490), 1993. (f) Tang, C. C.; Ma, F. P.; Zhang, K.; He, Z. J.; Jin, Y. C. Heteroatom Chem. 1995, 6, 413-417. (g) Rodriguez, O. P.; Thompson, C. M. Phosphorus, Sulfur Silicon Relat. Elem. 1996, 117, 101-110. (h) Kalir, A.; Kalir, H. H. In The Chemistry of Organophosphorus Compounds; Hartley, F. R., Ed.; Wiley: Chichester, New York, 1996; pp 767-780. (3) Edmundson, R. S. In The Chemistry of Organophosphorus Compounds; Hartley, F. R., Ed.; John Wiley & Sons: Chichester, 1996; Vol. 4, Chapter 5, pp 400-412. 10.1021/jo0348064 CCC: $25.00 © 2003 American Chemical Society
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J. Org. Chem. 2003, 68, 9916-9923
Published on Web 12/03/2003
Phosphonyl Radical Addition onto Alkenes
FIGURE 2. Phosphites 6, thiophosphites 7, dithiophosphites 8, and trithiophosphites 9, as well as radicals 10-13 generated therefrom.
SCHEME 1. Addition of Phosphites 6 and Thiophosphites 7 onto Alkenes 14
FIGURE 3. Structures of radical precursors 19-22, of radical 23, and of intermediates 24-26.
Our own studies on the radical chain addition of species 6 and 7 onto 1,1-difluoroalkenes showed the positive effect of the sulfur atom in 11 on the course of the reaction, when compared to the fully oxygenated analogue (i.e., 10) (Figure 2).5 More recently, we described the addition of S,S-dialkylphosphonodithioyl radicals 12 onto alkenes.6 In this paper, we report a more complete and comparative study on the generation of radicals 10, 11, 12, and 13 as well as on their behavior toward terminal alkenes. The lower stability of the P-S bond (45-50 kcal/mol versus 90-100 kcal/mol for the P-O bond) precluded us from using S,S-dialkyl dithiophosphites and trithiophosphites (8 and 9, respectively) as precursors of radicals 12 and 13. Thus, for instance, dithiophosphites 8 are notoriously difficult to prepare and handle and have been reported to disproportionate and to be prone to decomposition upon hydrolysis.7 In addition, the more stable, cyclic 1,3,2-dithiaphosphinane 2-oxide (8b, R, R ) -CH2CH2CH2-) has been shown to easily form oligomers or polymers.8,9 Analogously, attempts to prepare trithiophosphites have been reported to be unsuccessful, due (4) (a) Stiles, A. R.; Vaughan, W. E.; Rust, F. F. J. Am. Chem. Soc. 1958, 80, 714-716. (b) Pudovik, A. N.; Konovalova, I. V. Zh. Obshch. Khim. 1959, 29, 3338-3342; Chem. Abstr. 1960, 54, 15224b. (c) Kenny, R. L.; Fisher, G. S. J. Org. Chem. 1974, 39, 682-686. (d) Battiste, D. R.; Haseldine, D. L. Synth. Commun. 1984, 14, 993-1000. (e) Finke, M.; Kleiner, H.-J. Liebigs Ann. Chem. 1974, 741-750. (f) Dingwall, J. G.; Tuck, B. J. Chem. Soc., Perkin Trans. 1 1986, 2081-2090. (5) Piettre, S. R. Tetrahedron Lett. 1996, 37, 2233-2236. (6) Lopin, C.; Gautier, A.; Gouhier, G.; Piettre, S. R. Tetrahedron Lett. 2000, 41, 10195-10200. (7) (a) Hudson, R. F.; Keay, L. J. Chem. Soc. 1956, 3269-3271. (b) Kardanov, N. A.; Provotorova, N. P.; Petrovskii, P. V.; Godoviloc, N. N.; Kabachnik, M. I. Izv. Akad. Nauk. SSSR 1983, 2114-2121. (c) Al’fonsov, V. A.; Trusenev, A. G.; Batyeva, E. S.; Pudovic, M. A. Ivz. Akad. Nauk. SSSR 1991, 2103-2111. (8) (a) Nifant’ev, E. E.; Zavalishina, A. I.; Sorokina, S. F.; Chernyak, S. M. Dolk. Akad. Nauk. SSSR 1972, 203, 593-595. (b) Sorokina, S. F.; Zavalishina, A. I.; Nifant’ev, E. E. Zh. Obshch. Khim. 1973, 43, 750-752. (c) Nifant’ev, E. E.; Zavalishina, A. I.; Sorokina, S. F.; Blagoveshchenskii, V. S.; Yakovleva, O. P.; Esenina, E. V. Zh. Obshch. Khim. 1974, 44, 1694-1697. (9) In our hands, compound 8b was formed in very poor yields (
