An improved synthesis of vinyl- and β-iodovinyl sulfones by a molecular iodine-mediated one-pot iodosulfonationdehydroiodination reaction

Synthetic Communications

Volumn 43, Issue 12, 2013, Pages 1692-1707

  Sawangphon, Tassaporn ^a   Katrun, Praewpan ^a   Chaisiwamongkhol, Korbua ^a   Pohmakotr, Manat ^a   Reutrakul, Vichai ^a   Jaipetch, Thaworn ^b   Soorukram, Darunee ^a   Kuhakarn, Chutima ^a  

^a Mahidol University   (Thailand)

^b MAHIDOL UNIVERSITY   (Thailand)

Author keywords

Alkenes; Alkynes; Iodine; Sulfur; Vinyl sulfones

Indexed keywords

ALIPHATIC COMPOUND; ALKYNE; BETA IODOVINYL SULFONE; STYRENE DERIVATIVE; UNCLASSIFIED DRUG; VINYL DERIVATIVE;

ARTICLE; CHEMICAL REACTION; DEHYDROIODINATION; ELECTRON TRANSPORT; IODINATION; IODOSULFONATION; ONE POT SYNTHESIS; SULFONATION;

EID: 84876263843     PISSN: 00397911     EISSN: 15322432     Source Type: Journal    
DOI: 10.1080/00397911.2012.663448     Document Type: Article

References (85)

1. For recent works, see (a) Honma, M.; Takeda, H.; Takano, M.; Nakada, M. Development of catalytic asymmetric intramolecular cyclopropanation of a -diazo-b-keto sulfones and applications to natural product synthesis. Synlett 2009, 1695-1712;
2. (b) Back, T. G. Design and synthesis of some biologically interesting natural and unnatural products based on organosulfur and selenium chemistry. Can. J. Chem. 2009, 87, 1657-1674;
3. (c) Martinelli, F.; Palmieri, A.; Petrini, M. Arylsulfonyl group: Activating properties and recent synthetic applications. Phosphorus, Sulfur Silicon Relat. Elem. 2011, 186, 1032-1045;
4. (d) Meadows, D. C.; Gervay-Hague, J. Vinyl sulfones: Synthetic preparations and medicinal chemistry applications. Med. Res. Rev. 2006, 26, 793-814; (Pubitemid 44735554)
5. (e) Liu, S.; Zhou, B.; Yang, H.; He, Y.; Jiang, Z-X.; Kumar, S.; Wu, L.; Zhang, Z.-Y. Aryl vinyl sulfonates and sulfones as active site-directed and mechanism-based probes for protein tyrosine phosphatases. J. Am. Chem. Soc. 2008, 130, 8251-8260. (Pubitemid 351898544)
6. For cysteine protease inhibitors, see (a) Liu, S.; Hanzlik, R. P. Structure-activity relationships for inhibition of papain by peptide Michael acceptors. J. Med. Chem. 1992, 35, 1067-1075;
7. (b) Palmer, J. T.; Rasnick, D.; Klaus, J. L.; Brömme, D. Vinyl sulfones as mechanism-based cysteine protease inhibitors. J. Med. Chem. 1995, 38, 3193-3196;
8. (c) Roush, W. R.; Gwaltney II, S. L.; Cheng, J.; Scheidt, K. A.; McKerrow, J. H.; Hansell, E. Vinyl sulfonate esters and vinyl sulfonamides: Potent, irreversible inhibitors of cysteine proteases. J. Am. Chem. Soc. 1998, 120, 10994-10995; (Pubitemid 28507454)
9. (d) Shenai, B. R.; Lee, B. J.; Alvarez-Hernandez, A.; Chong, P. Y.; Emal, C. D.; Neitz, R. J.; Roush, W. R.; Rosenthal, P. J. Structure-activity relationships for inhibition of cysteine protease activity and development of Plasmodium falciparum by peptidyl vinyl sulfones. Antimicrob. Agents Ch. 2003, 47, 154-160; (Pubitemid 36070357)
10. (e) Wang, G.; Mahesh, U.; Chen, G. Y. J.; Yao, S. Q. Solid-phase synthesis of peptide vinyl sulfones as potential inhibitors and activity-based probes of cysteine proteases. Org. Lett. 2003, 5, 737-740; (Pubitemid 37141091)
11. (f) Ettari, R.; Nizi, E.; Francesco, M. E. D.; Dude, M.-A.; Pradel, G.; Viĉík, R.; Schirmeister, T.; Micale, N.; Grasso, S.; Zappalà, M. Development of peptidomimetics with a vinyl sulfone warhead as irreversible falcipain-2 inhibitors. J. Med. Chem. 2008, 51, 988-996. (Pubitemid 351304707)
12. For HIV-1 inhibitors, see (g) Meadows, D. C.; Sanchez, T.; Neamati, N.; North, T. W.; Gervay-Hague, J. Ring substituent effects on biological activity of vinyl sulfones as inhibitors of HIV-1. Bioorg. Med. Chem. 2007, 15, 1127-1137. (Pubitemid 44880699)
13. For sortase inhibitors, see (h) Frankel, B. A.; Bentley, M.; Kruger, R. G.; McCafferty, D. G. Vinyl sulfones: Inhibitors of SrtA, a transpeptidase required for cell wall protein anchoring and virulence in Staphylococcus aureus. J. Am. Chem. Soc. 2004, 126, 3404-3405. (Pubitemid 38366714)
14. For tyrosine phosphatase inhibitors, see (i) Liu, S.; Zhou, B.; Yang, H.; He, Y.; Jiang, Z.-X.; Kumar, S.; Wu, L.; Zhang, Z.-Y. Aryl vinyl sulfonates and sulfones as active site-directed and mechanism-based probes for protein tyrosine phosphatases. J. Am. Chem. Soc. 2008, 130, 8251-8260. (Pubitemid 351898544)
15. Vinyl sulfones as Michael acceptors, see (a) Farthing, C. N.; Marsden, S. P. Chiral vinyl dioxazaborocines in synthesis: Asymmetric cuprate additions to b-boronyl acrylates and vinyl sulfones. Tetrahedron Lett. 2000, 41, 4235-4238; (Pubitemid 30367373)
16. (b) Esteves, A. P.; Silva, M. E.; Rodrigues, L. M.; Oliveira-Campos, A. M. F.; Hrdina, R. Aza-Michael reactions with vinyl sulfones and amberlyst-15 as catalyst. Tetrahedron Lett. 2007, 48, 9040-9043; (Pubitemid 350122682)
17. (c) Sulzer-Mossé , S.; Alexakis, A.; Mareda, J.; Bollot, G.; Bernardinelli, G.; Filinchuk, Y. Enantioselective organocatalytic conjugate addition of aldehydes to vinyl sulfones and vinyl phosphonates as challenging Michael acceptors. Chem. Eur. J. 2009, 15, 3204-3220.
18. Vinyl sulfones as dienophiles, see (d) Carr, R. V. C.; Paquette, L. A. An ethylene and terminal olefin equivalent in [4+2]p cycloadditions: General synthetic application of phenyl vinyl sulfone to the construction of functionalized six-membered rings. J. Am. Chem. Soc. 1980, 102, 853-855;
19. (e) Krasovsky, A. L.; Nenajdenko, V. G.; Balenkova, E. S. Diels-Alder reactions of b-trifluoroacetylvinylsulfones. Tetrahedron 2001, 57, 201-209;
20. (f) Padwa, A.; Lipka, H.; Watterson, S. H.; Murphree, S. S. Phenylsulfonyl ene-allenes as efficient precursors to bicyclic systems via intramolecular [2+2]-cycloaddition reactions. J. Org. Chem. 2003, 68, 6238-6250; (Pubitemid 36961009)
21. (g) Llamas, T.; Arrayá s, R. G.; Carretero, J. C. Catalytic enantioselective 1,3-dipolar cycloaddition of azomethine ylides with vinyl sulfones. Org. Lett. 2006, 8, 1795-1798; (Pubitemid 43692161)
22. (h) López-Pé rez, A.; Robles-Machín, R.; Adrio, J.; Carretero, J. C. Oligopyrrole synthesis by 1,3-dipolar cycloaddition of azomethine ylides with bissulfonyl ethylenes. Angew. Chem. Int. Ed. 2007, 46, 9261-9264; (Pubitemid 350292154)
23. (i) Gao, Y.; Lam, Y. [3+2] Cycloaddition reactions in the synthesis of triazolo[ 4,5-b]pyridin-5-ones and pyrrolo[3,4-b]pyridin-2-ones. J. Comb. Chem. 2008, 10, 327-332.
24. b-Elimination and sulfur oxidation: (a) Brace, N. O. An economical and convenient synthesis of phenyl vinyl sulfone from benzenethiol and 1,2-dichloroethane. J. Org. Chem. 1993, 58, 4506-4508;
25. (b) Kroll, F. E. K.; Morphy, R.; Rees, D.; Gani, D. Resinimmobilised benzyl and aryl vinyl sulfones: New versatile traceless linkers for solid-phase organic synthesis. Tetrahedron Lett. 1997, 38, 8573-8576; (Pubitemid 27497114)
26. (c) Orita, A.; Katakami, M.; Yasui, Y.; Kurihara, A.; Otera, J. Integrated chemical process for green chemistry: One-pot synthesis of 3-substituted 5-(b-sulfonylvinyl)indoles by in situ generation of toxic vinyl sulfone. Green Chem. 2001, 3, 13-16; (Pubitemid 33232454)
27. (d) Magnier, E.; Tordeux, M.; Goumont, R.; Magder, K.; Wakselman, C. Perfluoroalkylation of 2-mercaptoethanol as a key step for a new synthesis of perfluoroalkyl vinyl sulfides, sulfoxides, and sulfones. J. Fluorine Chem. 2003, 124, 55-59.
28. (e) da Silva Corre a, C. M. M.; Waters, W. A. Reactions of the free toluene-p-sulphonyl radical, part 1: Diagnostic reactions of free radicals. J. Chem. Soc. C 1968, 1874-1879;
29. (f) Liu, L. K.; Chi, Y.; Jen, K.-Y. Copper-catalyzed additions of sulfonyl iodides to simple and cyclic alkenes. J. Org. Chem. 1980, 45, 406-410;
30. (g) Harwood, L. M.; Julia, M.; Thuillier, G. L. Organic synthesis with sulphones, XVII: The anti-Markownikoff halosulphonylation of olefins via an ionic pathway, and a new method of preparing benzenesulphonyl iodide. Tetrahedron 1980, 36, 2483-2487;
31. (h) Inomata, K.; Kobayashi, T.; Sasaoka, S.; Kinoshita, H.; Kotake, H. Convenient methods for the preparation of vinylic and allylic sulfones from alkenes. Chem. Lett. 1986, 289-292;
32. (i) Nájera, C.; Baldó, B.; Yus, M. Regio- and stereo-selective synthesis of b-sulphonyl-a,b-unsaturated carbonyl compounds via an iodosulphonylation-dehydroiodination reaction. J. Chem. Soc., Perkin Trans. 1 1988, 1029-1032;
33. (j) Nájera, C.; Sansano, J. M.; Yus, M. One-pot iodosulfonylation dehydroiodination of alkene: (E)-b-Tosylstyrene. J. Chem. Educ. 1995, 72, 664-665;
34. (k) Nair, V.; Augustine, A.; George, T. G.; Nair, L. G. An efficient one-pot synthesis of vinyl sulphones via CAN-mediated reaction of aryl sulphinates and alkenes. Tetrahedron Lett. 2001, 42, 6763-6765; (Pubitemid 32786766)
35. (l) Nair, V.; Augustine, A.; Suja, T. D. CAN-mediated reaction of aryl sulfinates with alkenes and alkynes: Synthesis of vinyl sulfones, b-iodovinyl sulfones, and acetylenic sulfones. Synthesis 2002, 2259-2265; (Pubitemid 35305191)
36. (m) Zhu, S.; Qin, C.; Xu, G.; Chu, Q. A convenient synthesis of a new push-pull alkenes: b-Alkoxyl vinyl trifluoromethyl sulfones. Tetrahedron Lett. 1998, 39, 5265-5268; (Pubitemid 28293805)
37. (n) Back, T. G.; Collins, S. Selenosulfonation: Boron trifluoride catalyzed or thermal addition of selenosulfonates to olefins: A novel regio- and stereocontrolled synthesis of vinyl sulfones. J. Org. Chem. 1981, 46, 3249-3256;
38. (o) Sas, W. The arenesulphonomercuriation of alkenes-A route to vinyl sulphones. J. Chem. Soc., Chem. Commun. 1984, 862-863;
39. (p) Qian, H.; Huang, X. Polystyrene-supported selenosulfonates: Efficient reagents for regio- and stereocontrolled synthesis of vinyl sulfones. Synlett 2001, 1913-1916; (Pubitemid 33135277)
40. (q) Edwards, G. L.; Muldoon, C. A.; Sinclair, D. J. Cyclic enol ether synthesis via arenesulfonyl iodide additions to alkynols. Tetrahedron 1996, 52, 7779-7788; (Pubitemid 26169863)
41. (r) Liu, X.; Duan, X.; Pan, Z.; Han, Y.; Liang, Y. Stereoselective synthesis of (Z)-b-chlorovinyl sulfones by addition of sulfonyl chlorides to acetylenes. Synlett 2005, 1752-1754. (Pubitemid 40992104)
42. (s) Popoff, I. C.; Dever, J. L.; Leader, G. R. a, b-Unsaturated sulfones via phosphonate carbanions. J. Org. Chem. 1969, 34, 1128-1130;
43. (t) Wang, G.; Yao, S. Q. Combinatorial synthesis of a small-molecule library based on the vinyl sulfone scaffold. Org. Lett. 2003, 5, 4437-4440. Hydrometallation reaction (Pubitemid 37490647)
44. (u) Huang, X.; Duan, D.-H. The synthesis of ethenyl bifunctional reagents containing a sulfone moiety and zirconium by the abnormal addition of Cp2Zr(H)Cl to internal acetylenic sulfones. Chem. Commun. 1999, 1741-1742; (Pubitemid 29414471)
45. (v) Huang, X.; Duan, D.; Zheng, W. Studies on hydrozirconation of 1-alkynyl sulfoxides or sulfones and the application for the synthesis of stereodefined vinyl sulfoxides or sulfones. J. Org. Chem. 2003, 68, 1958-1963; (Pubitemid 36504854)
46. (w) Duan, D.-H.; Huang, X. A facile regioand stereocontrolled synthesis of (E)-disubstituted vinyl sulfones via transformation of alkenylzirconocenes with sulfonyl chlorides. Synlett 1999, 317-318; (Pubitemid 29125469)
47. (x) Huang, X.; Liang, C.-G.; Xu, Q.; He, Q.-W. Alkyne-based, highly stereo- and regioselective synthesis of stereodefined functionalized vinyl tellurides. J. Org. Chem. 2001, 66, 74-80. Selenosulfonation of alkynes (Pubitemid 32057842)
48. (y) Back, T. G.; Collins, S.; Krishna, M. V.; Law, K.-W. Substitution reactions of organocuprates with β-(phenylseleno)vinyl sulfones derived from the selenosulfonation of acetylenes: A convenient and stereospecific preparation of vinyl sulfones and olefins from acetylenes. J. Org. Chem. 1987, 52, 4258-4264;
49. (z) Back, T. G.; Bethell, R. J.; Parvez, M.; Wehrli, D. Additions of organocopper reagents and heteroatom nucleophiles to 1-phenylseleno-2-(p- toluenesulfonyl)ethyne: Preparation of vinyl and allenic sulfones and formation of Michael, anti-Michael, and rearrangement products. J. Org. Chem. 1998, 63, 7908-7919; (Pubitemid 128723039)
50. (aa) Watanabe, S.; Yamamoto, K.; Itagaki, Y.; Iwamura, T.; Iwama, T.; Kataoka, T.; Tanabe, G.; Muraoka, O. Synthesis and reactivity of b-sulfonylvinylselenonium salts: A simple stereoselective synthesis of b-functionalized (Z)-vinyl sulfones. J. Chem. Soc., Perkin Trans. 1 2001, 239-247. Palladium-catalyzed reactions
51. (ab) Berteina, S.; Wendeborn, S.; Brill, W. K.-D.; Mesmaeker, A. D. Pd-mediated C-C bond formation with olefins and acetylenes on solid support: A scope and limitations study. Synlett 1998, 676-678; (Pubitemid 128694266)
52. (ac) Cacchi, S.; Fabrizi, G.; Goggiamani, A.; Parisi, L. M.; Bernini, R. Unsymmetrical diaryl sulfones and aryl vinyl sulfones through palladium-catalyzed coupling of aryl and vinyl halides or triflates with sulfinic acid salts. J. Org. Chem. 2004, 69, 5608-5614; (Pubitemid 39079613)
53. (ad) Kabalka, G. W.; Guchhait, S. K. Convenient synthesis of a, b-unsaturated sulfones via a Mizoroki-Heck reaction of arylboronic acids with phenyl vinyl sulfones. Tetrahedron Lett. 2004, 45, 4021-4022; (Pubitemid 38581804)
54. (ae) Reeves, D. C.; Rodriguez, S.; Lee, H.; Haddad, N.; Krishnamurthy, D.; Senanayake, C. H. Palladiumcatalyzed coupling of vinyl tosylates with arylsulfinate salts. Tetrahedron Lett. 2009, 50, 2870-2873. Copper-catalyzed reactions
55. (af) Bao, W.; Wang, C. CuI=L-proline potassium salt-catalysed synthesis of vinyl sulfones via coupling reaction of vinyl bromides with sulfinic acid salts in ionic liquid. J. Chem. Res. 2006, 6, 396-397; (Pubitemid 44085001)
56. (ag) Bian, M.; Xu, F.; Ma, C. Anion-functionalized ionic liquids enhance the CuI-catalyzed cross-coupling reaction of sulfinic acid salts with aryl halides and vinyl bromides. Synthesis 2007, 2951-2956. Cross-metathesis reactions (Pubitemid 47598947)
57. (ah) Grela, K.; Bieniek, M. Highly selective cross-metathesis with phenyl vinyl sulphone using the ''second-generation'' Grubbs' catalyst. Tetrahedron Lett. 2001, 42, 6425-6428; (Pubitemid 32772707)
58. (ai) Michrowska, A.; Bieniek, M.; Kim, M.; Klajn, R.; Grela, K. Cross-metathesis reaction of vinyl sulfones and sulfoxides. Tetrahedron 2003, 59, 4525-4531. Reaction of 1,2-dibromoalkanes with sulfinic acid sodium salts (Pubitemid 36703279)
59. (aj) Guan, Z.-H.; Zuo, W.; Zhao, L.-B.; Ren, Z.-H.; Liang, Y.-M. An economical and convenient synthesis of vinyl sulfones. Synthesis 2007, 1465-1470. (Pubitemid 46847953)
60. (a) Xu, Q.-L.; Dai, L.-X.; You, S.-L. Tandem Ir-catalyzed allylic substitution reaction of allyl sulfinates and isomerization. Org. Lett. 2010, 12, 800-803;
61. (b) Taniguchi, N. Stereoselective synthesis of (E)-alkenyl sulfones from alkenes or alkynes via copper-catalyzed oxidation of sodium sulfinates. Synlett 2011, 1308-1312;
62. (c) Das, B.; Lingaiah, M.; Damodar, K.; Bhunia, N. An efficient synthesis of vinyl sulfones from alkenes and aryl sulfinates. Synthesis 2011, 2941-2944;
63. (d) Song, R.-J.; Liu, Y.; Liu, Y.-Y.; Li, J.-H. Palladium-catalyzed conjugate addition to electron-deficient alkynes with benzenesulfinic acid derived from 1,2-bis(phenylsulfonyl)ethane: Selective synthesis of (E)-vinyl sulfones. J. Org. Chem. 2011, 76, 1001-1004.
64. Katrun, P.; Chiampanichayakul, S.; Korworapan, K.; Pohmakotr, M.; Reutrakul, V.; Jaipetch, T.; Kuhakarn, C. PhI(OAc)2=KI-mediated reaction of aryl sulfinates with alkenes, alkynes, and a, b-unsaturated carbonyl compounds: Synthesis of vinyl sulfones and b-iodovinyl sulfones. Eur. J. Org. Chem. 2010, 5633-5641.
65. For reviews, see (a) Togo, H.; Iida, S. Synthetic use of molecular iodine for organic synthesis. Synlett 2006, 2159-2175; (Pubitemid 44393514)
66. (b) Banerjee, A. K.; Vera, W.; Mora, H.; Laya, M. S.; Bedoya, L.; Cabrera, E. V. Iodine in organic synthesis. J. Sci. Ind. Res. 2006, 65, 299-308;
67. (c) Das, S.; Borah, R.; Devi, R. R.; Thakur, A. J. Molecular iodine in protection and deprotection chemistry. Synlett 2008, 2741-2762;
68. (d) Jereb, M.; Vražič, D.; Zupan, M. Iodine-catalyzed transformation of molecules containing oxygen functional groups. Tetrahedron 2011, 67, 1355-1387;
69. (e) Banerjee, A. K.; Laya, M. S.; Cabrera, E. V. Iodocyclization: Past and present examples. Curr. Org. Chem. 2011, 15, 1058-1080.
70. (a) Padwa, A.; Ishida, M. Silver tetrafluoroborate induced reaction of trimethylsilyl enol ethers with 2,3-diiodo-1-(phenylsulfonyl)-1-propene as a method for preparing substituted furans. Tetrahedron Lett. 1991, 32, 5673-5676;
71. (b) Rao, C. J.; Knochel, P. A direct preparation of vinylogous acyl anion equivalents. J. Org. Chem. 1991, 56, 4593-4596
72. (c) Knochel, P.; Rao, C. J. Preparation and reactivity of functionalized alkenyl-zinc, -copper, and -chromium organometallics. Tetrahedron 1993, 49, 29-48;
73. (d) Short, K. M.; Ziegler, C. B. Jr. 5- and 6-membered ring compounds from (E)-b-iodo(vinyl)sulfones. Tetrahedron Lett. 1995, 36, 355-356;
74. (e) Zoller, T.; Uguen, D. An efficient procedure for preparing chydroxy a, b-unsaturated sulfones. Eur. J. Org. Chem. 1999, 1545-1550;
75. (f) Gu, X.-X.; Xie, M.-H.; Zhao, X.-Y.; Sun, Y.; Zhang, W.; Xie, F.-D.; Wang, S.-W. An efficient synthesis of polysubstituted 1,3-enynes from (E)-b-iodovinyl sulfones and terminal alkynes. Chin. J. Chem. 2008, 26, 1625-1629.
76. (a) Fu, C.; Xu, C.; Huang, Z.-Z.; Huang, X. a, b-Unsaturated sulfones by the Wittig reaction of stable ylide with aldehydes under microwave irradiation. Org. Prep. Proced. Internat. 1997, 29, 587-589; (Pubitemid 127387008)
77. (b) Kamigata, N.; Sawada, H.; Kobayashi, M. Reactions of arenesulfonyl chlorides with olefins catalyzed by a ruthenium(I1) complex. J. Org. Chem. 1983, 48, 3793-3796.
78. Deng, G.; Zou, J. The first nucleophilic substitution reaction of organoindium reagents with sulfonyl chlorides: A facile method for preparation of vinyl sulfones. Arkivoc 2010, 2, 186-194.
79. Nair, V.; Augustine, A.; Panicker, S.; Suja, T. D.; Mathai, S. Cerium(IV) ammonium nitrate (CAN)-mediated sulfonylation of styrenes: Some interesting observations. Res. Chem. Intermed. 2003, 29, 213-226.
80. Holler, M.; Sin, H. S.; James, A.; Burger, A.; Trintsch, D.; Biellmeann, J.-F. (E)-1-Alkyl-4-[2-(alkylsulfonyl)-1-ethenyl]pyridinium salts: Reaction of thiol groups giving rise to chromophoric (E)-1-alkyl-4-[2-(alkylsulfanyl)-1- ethenyl]pyridinium salts. Chem. Eur. J. 2000, 6, 2053-2062.
81. Jang, W. B.; Jeon, H. J.; Oh, D. Y. Direct sulfonylation of lithiated alkyl phosphonates with benzenesulfonyl fluoride: Facile method for preparation of a -sulfonyl alkyl phosphonates and vinyl sulfones. Synth. Commun. 1998, 28, 1253-1256. (Pubitemid 28191960)
82. Kazuyoshi, T.; Kanoko, T.; Maki, M.; Haruo, O. Single-step preparation of allylic sulfides having 1-phenyltetrazole-5-thio group from allylic alcohols using S,S0-bis(1-phenyl-1H-tetrazol-5-yl) dithiocarbonate and reactions involving the allylic sulfides. Tetrahedron Lett. 1988, 29, 4105-4108.
83. Inomata, K.; Hirata, T.; Sasada, Y.; Asada, T.; Senda, H.; Kinoshita, H. Crystallographic approach to the origin of ''syn effect.'' Chem. Lett. 1990, 12, 2153-2156.
84. (a) Mori, Y.; Yaegashi, K.; Furukawa, H. Synthesis of trans-fused tetrahydropyrans via intramolecular cyclization of a -bromo-c'-hydroxy ketones. Tetrahedron Lett. 1999, 40, 7239-7242; (Pubitemid 29456969)
85. (b) Ashwell, M.; Clegg, W.; Jackson, R. F. W. Phenylsulphonyloxiranes as functionalised acyl anion equivalents in organic synthesis. J. Chem. Soc., Perkin Trans. 1 1991, 897-908.