References and Notes
1 For a recent review including chemical and biological aspects of sulfenates, see: O’Donnell JS.
Schwan AL.
J. Sulfur Chem.
2004,
25:
183
2a
Sandrinelli F.
Perrio S.
Beslin P.
J. Org. Chem.
1997,
62:
8626
2b
Sandrinelli F.
Perrio S.
Beslin P.
Org. Lett.
1999,
1:
1177
2c
Sandrinelli F.
Perrio S.
Averbuch-Pouchot M.-T.
Org. Lett.
2002,
4:
3619
2d
Sandrinelli F.
Fontaine G.
Perrio S.
Beslin P.
J. Org. Chem.
2004,
69:
6916
2e
Martin C.
Sandrinelli F.
Perrio C.
Perrio S.
Lasne M.-C.
J. Org. Chem.
2006,
71:
210
Examples of alkynyl alkyl sulfoxides are scarce, in contrast to alkynyl aryl derivatives. One reason is probably a relative instability. For example, polymerization upon standing or decomposition with a vigorous evolution of gas has been mentioned:
3a
Russel GL.
Ochrymowycz LA.
J. Org. Chem.
1970,
35:
2106
3b
Truce WE.
Lusch MJ.
J. Org. Chem.
1978,
43:
2252
4 The most relevant alternative routes to sulfenates are the oxidative cleavage of 1-alkynyl sulfoxides using a Pd(0) catalyst followed by transmetallation with Et2Zn, an addition/elimination methodology with β-sulfinylacrylates and a retro-Michael reaction initiated by a base from β-sulfinylesters. See ref. 1 and: Caupène C.
Boudou C.
Perrio S.
Metzner P.
J. Org. Chem.
2005,
70:
2812
5 The analogous sulfur anion with a higher oxidation state(sulfinate) readily decomposes with SO2 evolution: Carpino LA.
Rynbrandt RH.
J. Am. Chem. Soc.
1966,
88:
5682
6
D’hooge B.
Smeets S.
Toppet S.
Dehaen W.
Chem. Commun.
1997,
1753
7a
Brandsma L.
Zwikker JW.
Bilthoven N.
Product Subclass 11: Lithium Alkynolates, Alkanethiolates and Alkyneselenolates, In Science of Synthesis
Vol. 8a:
Snieckus V.
Georg Thieme Verlag;
Stuttgart:
2006.
p.305
7b
Sukhai RS.
Meijer J.
Brandsma L.
Recl. Trav. Chim. Pays-Bas
1977,
96:
79
8
Wilkins DJ.
Bradley PA.
Product Class 9: 1,2,3-Thiadiazoles, In Science of Synthesis
Vol. 13:
Storr RC.
Gilchrist TL.
Georg Thieme Verlag;
Stuttgart:
2004.
p.253
9a
Raap R.
Micetich RG.
Can. J. Chem.
1968,
46:
1057
9b
Schaumann E.
Grabley F.-F.
Liebigs Ann. Chem.
1979,
1746
10
Al-Masoudi N.
Hassan NA.
Al-Soud YA.
Schmidt P.
Gaafar AE.-DM.
Weng M.
Marino S.
Schoch A.
Amer A.
Jochims JC.
J. Chem. Soc., Perkin Trans. 1
1998,
947
The hydrazones were fully characterized and the data collected were in agreement with those previously reported:
11a
Rabjohn N.
Barnstorff HD.
J. Am. Chem. Soc.
1953,
75:
2259
11b
Al-Smadi M.
Ratrout S.
Molecules
2004,
9:
957
11c
Cavill JL.
Elliott RL.
Evans G.
Jones IL.
Platts JA.
Ruda AM.
Tomkinson NCO.
Tetrahedron
2006,
62:
410
12a
Hurd CD.
Mori RI.
J. Am. Chem. Soc.
1955,
77:
5359
12b
Fujita M.
Kobori T.
Hiyama T.
Kondo K.
Heterocycles
1993,
36:
33
12c
Stanetty P.
Turner M.
Mihovilovic MD. In Targets in Heterocyclic Systems
Vol. 3:
Attanasi OA.
Spinelli D.
Società Chimica Italiana;
Rome:
1999.
p.265
12d
Hu Y.
Baudart S.
Porco JA.
J. Org. Chem.
1999,
64:
1049
12e
Attanasi OA.
De Crescentini L.
Filippone P.
Mantellini F.
Synlett
2001,
557
12f
Thomas EW.
Nishizawa EE.
Zimmermann DC.
Williams DJ.
J. Med. Chem.
1985,
28:
442
12g
Kobori T.
Fujita M.
Hiyama T.
Kondo K.
Synlett
1992,
95
13
4-(1,1-Dimethylethyl)-1,2,3-thiadiazole (3a):27a R1 = t-Bu; beige powder, (89%); mp 23 °C (Lit.27a 23 °C); 1H NMR (250 MHz, CDCl3): δ = 1.51 (s, 9 H), 8.15 (s, 1 H);
13C NMR (62.9 MHz, CDCl3): δ = 30.9, 34.0, 129.3, 173.6; IR (NaCl): 2964, 2870, 1490, 1462, 1244, 964, 890 cm-1; MS (EI): m/z (%) = 142 (11) [M+], 57 (100), 43 (97), 41 (98).
4-Phenyl-1,2,3-thiadiazole (3b):27b
R1 = Ph; orange solid recrystallized from n-hexane (83%); mp 76-78 °C (Lit.27b 77-78 °C); 1H NMR (250 MHz, CDCl3): δ 7.41-7.55 (m, 3 H), 8.02-8.07 (m, 2 H), 8.65 (s, 1 H); 13C NMR (62.9 MHz, CDCl3): δ = 127.8, 129.6, 129.9, 130.4, 131.2, 163.3; IR (NaCl): 3072, 1462, 1442, 1220, 766, 692 cm-1; MS (EI): m/z (%) = 162 (6) [M+], 134 (100), 90 (18).
14
4-Methyl-1,2,3-thiadiazole (3c):27c
R1 = Me; white solid which melted rapidly at r.t. (43%); 1H NMR (250 MHz, CDCl3): δ = 2.81 (s, 3 H), 8.17 (s, 1 H);
13C NMR (62.9 MHz, CDCl3): δ = 13.93, 132.6, 160.0; IR (NaCl): 3104, 1494, 1444, 1224 cm-1; MS (CI): m/z (%) = 101 (100) [M + H+], 71 (79).
15
5-Chloro-4-methyl-1,2,3-thiadiazole: Orange oil (8%); 1H NMR (250 MHz, CDCl3): δ = 2.7 (s, 3 H); MS (CI): m/z (%) = 135 (100) [M + H+] 35Cl, 137 (35) [M + H+] 37Cl, 71 (50).
16
Wu P.-L.
Peng S.-Y.
Magrath J.
Synthesis
1996,
249
17
N
-(1,2,2-Trimethylpropylidene)benzenesulfonamide (4). To a mixture of pinacolone (9.1 mL, 73 mmol) and benzenesulfonamide (5.8 g, 36.5 mmol) in toluene (360 mL), Ti(OEt)4 (25 g, 110 mmol) was added dropwise while stirring. The reaction mixture was slowly heated to reflux (oil bath temperature at 115 °C). After refluxing for 20 h, the yellow mixture was cooled to r.t. and an aq NaOH solution (0.5 M, 350 mL) was added slowly. The white gel of titanium oxides formed was filtered through celite to give a biphasic filtrate. The organic phase was separated and the aq layer extracted with Et2O (2 × 150 mL). The combined organic extracts were washed with sat. aq NaCl solution (100 mL) and dried over MgSO4. Filtration and concen-tration under reduced pressure led to imine 4 (6.5 g, 27 mmol, 75%) as a yellowish solid. The product was used without further purification.
18 Imine 4 was also prepared in good yield (70-80%) by a free radical rearrangement of O-sulfinyl oximes (Hudson reaction) prepared by the reaction of pinacolone oxime with benzenesulfinyl chloride in the presence of triethylamine. Purification of the crude material is essential: Brown C.
Hudson RF.
Record KAF.
J. Chem. Soc., Perkin Trans. 2
1977,
822
19
Camps F.
Coll J.
Messeguer A.
Pujol F.
J. Org. Chem.
1982,
47:
5402
20
trans
-3-(1,1-Dimethylethyl)-3-methyl-2-(phenyl-sulfonyl)oxaziridine (1). KF (8.5 g, 146.8 mmol) was dried by heating at 120 °C for 2 h under reduced pressure (1 Torr) and a solution of commercial MCPBA (70%, 18 g, 73.4 mmol) in CH2Cl2 (300 mL) previously dried over MgSO4 was added. A solution of crude imine 4 (11.7 g, 48.9 mmol) was added and the resulting white suspension was stirred at 0 °C for 3 h and then for a further 12 h at r.t. After filtration to remove the insoluble materials and concen-tration, the residue was filtered through SiO2 with CH2Cl2 as eluent to afford oxaziridine 1 (8.77 g, 34.4 mmol, 71%).
Various oxidizing agents were tested using successful experimental conditions reported in the synthesis of other N-sulfonyloxaziridines. However, most of them gave very disappointing results with, for example, no reaction taking place using Oxone® and formation of hydrolysis products using H2O2:
21a
Davis FA.
Chattopadhyay S.
Towson JC.
Lal S.
Reddy T.
J. Org. Chem.
1988,
53:
2087
21b
Page PCB.
Heer JP.
Bethell D.
Lund A.
Collington EW.
Andrews DM.
J. Org. Chem.
1997,
62:
6093
22
Crystal-structure determination of 1: Single crystals of oxaziridine 1, suitable for X-ray crystallographic analysis, were obtained by slow evaporation of n-hexane. X-ray diffraction experiments for the monocrystal of 1 were performed at 293.2 K with graphite-monochromatized Mo Kα radiation on an Enraf-Nonius CAD-4 diffractometer. Formula C12H17NO3S, formula weight 255, crystal system triclinic, space group P-1 (n° 2), a = 9.013 (1) Å, b = 9.169 (4) Å, c = 9.528 (3) Å, α = 108.39 (3)°, β = 108.38 (2)°, γ = 70.09 (2)°, V = 683.2 (4) Å3, Z = 2, density calcd = 1.24 g/cm3, µ = 2.3 cm-1, R = 0.034, wR = 0.0515. Selected bond lengths (Å) and angles (°): O1-C1 1.422 (1), O1-N1 1.484 (1), N1-C1 1.450 (2), S1-N1 1.704 (1), S1-O3 1.421 (1), S1-C7 1.750 (1), C7-C12 1.371 (2), C7-C8 1.374 (2), C1-C2 1.500(2), C1-C3 1.527 (2), C3-C6 1.536 (2), N1-O1-C1 59.90 (7), N1-O1-C1 57.84 (7), O1-C1-N1 62.19 (7), S1-N1-C1 120.27 (9), O2-S1-O3 120.03 (7), O2-S1-N1 102.29 (6), O3-S1-N1 114.31 (6), S1-N1-C1 120.27 (9). Data reduction: TEXSAN (Molecular Structure Corporation). Program(s) used to solve structure: SIR92. Program(s) used to refine structure: TEXSAN. Software used to prepare material for publication: TEXSAN. Crystallographic data for compound 1 have been deposited at the Cambridge Crystallographic Data Centre, CCDC No 615446. Copies of this information may be obtained free of charge from The Director, CCDC, 12 Union Road, Cambridge, CB2 1EZ, UK; +44 (1223)336408; E-mail: deposit@ccdc.cam.ac.uk or http://www.ccdc.cam.ac.uk.
23a
Hogg DR.
Robertson A.
J. Chem. Soc., Perkin Trans. 1
1979,
1125
23b
Kobayashi M.
Toriyabe K.
Sulfur Lett.
1985,
3:
117
24 This sulfoxide was successfully prepared by thioether oxidation: Villar JM.
Delgado A.
Llebaria A.
Moretó JM.
Molins E.
Miravitlles C.
Tetrahedron
1996,
52:
10525
25
General Procedure for the Synthesis of 1-Alkynyl Sulfoxides 2: A solution of thiadiazole 3 (1.00 mmol) in anhyd THF (5 mL) was cooled to -78 °C and MeLi (0.69 mL of a 1.6 M solution in Et2O, 1.1 mmol) was added dropwise. After stirring at -78 °C for 1 h, a solution of oxaziridine 1 (267 mg, 1.05 mmol) in anhyd THF (2 mL) was slowly added dropwise (exothermic reaction). The reaction mixture was stirred at this temperature for 30 min and treated with the alkyl halide (1-5 equiv). The reaction mixture was then warmed to -20 °C over 1.5 h and then the cold bath was removed. After stirring for a further 1.5 h at r.t., the reaction mixture was treated with sat. aq NaCl solution and the product was extracted with Et2O (3 × 20 mL). The combined organic extracts were washed with sat. aq NaCl solution (3 × 10 mL) and dried over MgSO4. After filtration and concentration under reduced pressure, the residue was purified by column chromatography (PE-EtOAc mixtures) to give the anticipated sulfoxides 2.
1-Benzylsulfinyl-3,3-dimethylbut-1-yne (2a
1
): Obtained from thiadiazole 3a (R1 = t-Bu, 142 mg, 1 mmol) using benzyl bromide (R2 = Bn, 130 µL, 1.1 mmol) as the electrophile gave 2a
1
as a colorless oil (170 mg, 0.77 mmol, 77%); R
f
= 0.19 (PE-EtOAc, 4:1);
1H NMR (250 MHz, CDCl3): δ = 1.22 (s, 9 H), 4.25 (s, 2 H), 7.35-7.37 (m, 5 H);
13C NMR (62.9 MHz, CDCl3): δ = 28.8, 30.3, 63.1, 75.8, 113.9, 129.0, 129.1, 129.6, 130.9; IR (NaCl) 3032, 2972, 2928, 2868, 2160 (C≡C), 1454, 1252, 1060 cm-1; MS (EI): m/z (%) = 220 (1) [M+], 91 (100), 65 (14); Anal. Calcd for C13H16OS: C, 70.87; H, 7.32; S, 14.55. Found: C, 70.75; H, 7.47; S, 14.76.
1-Ethylsulfinyl-3,3-dimethylbut-1-yne (2a
2
). Obtained from thiadiazole 3a (R1 = t-Bu, 142 mg, 1 mmol) using ethyl iodide (R2 = Et, 0.4 mL, 5 mmol) as the electrophile gave 2a
2
as a colorless oil (92 mg, 0,58 mmol, 58%); (R
f
= 0.3 (PE-EtOAc, 4:1); 1H NMR (250 MHz, CDCl3): δ = 1.29 (s, 9 H), 1.42 (t, J = 7.4 Hz, 3 H), 2.98 and 3.06 (AB part of ABX3, J
AB = 13 Hz, J
AX = J
BX = 7.4 Hz, 2 H); 13C NMR (62.9 MHz, CDCl3): δ = 6.8, 28.8, 30.4, 50.5, 75.7, 112.6; IR (NaCl): 2972, 2932, 2870, 2160 (C≡C), 1456, 1252, 1070 cm-1; MS (EI): m/z (%) = 158 (47) [M+], 142 (33), 130 (68), 115 (100); HRMS m/z calcd for C8H14OS: 158.0765; found: 158.0769.
3,3-Dimethyl-1-methylsulfinylbut-1-yne (2a
3
). Obtained from thiadiazole 3a (R1 = t-Bu, 142 mg, 1 mmol) using methyl iodide (R2 = Me, 186 µL, 3 mmol) as the electrophile gave 2a
3
as a pale pink oil (123 mg, 0,85 mmol, 85%); R
f
= 0.32 (PE-EtOAc, 1:1); 1H NMR (250 MHz, CDCl3): δ = 1.29 (s, 9 H), 2.92 (s, 3 H); 13C NMR (62.9 MHz, CDCl3): δ = 28.8, 30.4, 44.1, 77.7, 112.1; IR (NaCl): 2972, 2930, 2870, 2158 (C≡C), 1456, 1252, 1070 cm-1; MS (EI): m/z (%) = 144 (100) [M+], 129 (22), 113 (25), 81 (42); HRMS m/z calcd for C7H12OS: 144.0608; found: 144.0611.
(3,3-Dimethylbut-1-ynylsulfinyl)acetic acid ethyl ester (2a
4
). Obtained from thiadiazole 3a (R1 = t-Bu, 142 mg, 1 mmol) using 2-bromoacetic acid ethyl ester (R2 = CH2CO2Et, 0.12 mL, 1.1 mmol) as the electrophile gave 2a
4
as a colorless oil (162 mg, 0.75 mmol, 75%); R
f
= 0.21 (PE-EtOAc, 4:1);
1H NMR (250 MHz, CDCl3): δ = 1.29 (s, 9 H), 1.32 (t, J = 7.1 Hz, 3 H), 3.92 and 4.08 (ΑΒ, J = 13.6 Hz, 2 H), 4.26 (q, J = 7.1 Hz, 2 H); 13C NMR (62.9 MHz, CDCl3): δ = 14.5, 29.0, 30.3, 61.4, 62.6, 75.7, 114.0, 164.6; IR (NaCl): 2974, 2932, 2870, 2160 (C≡C), 1740 (C=O), 1456, 1366, 1252, 1070 cm-1; MS (EI): m/z (%) = 216 (35) [M+], 201 (62), 173 (80), 113 (36), 67 (38), 59 (48), 43 (100); Anal. Calcd for C10H16O3S: C, 55.53; H, 7.46; S, 14.82. Found: C, 55.63; H, 7.46; S, 14,52.
1-Benzylsulfinyl-2-phenylacetylene (2b
1
). Obtained from thiadiazole 3b (R1 = Ph, 162 mg, 1 mmol) using benzyl bromide (R2 = Bn, 0.130 mL, 1.1 mmol) as the electrophile gave 2b
1
as an orange oil which needed to be purified quickly on SiO2 and stored in a fridge (120 mg, 0.50 mmol, 50%); R
f
= 0.30 (PE-EtOAc, 4:1);
1H NMR (250 MHz, CDCl3): δ = 4.39 (pseudo s, 2 H), 7.35-7.46 (m, 10 H);
13C NMR (62.9 MHz, CDCl3): δ = 63.1, 85.4, 103.7, 120.1, 128.7, 129.0, 129.1, 129.2, 129.4, 131.0, 132.6; IR (NaCl): 3060, 3030, 2974, 2922, 2164 (C≡C), 1490, 1452, 1246, 1060 cm-1; MS (CI): m/z (%) = 241 (100) [M + H+], 181 (65), 107 (95), 91 (55); HRMS (CI): m/z calcd for C15H13OS: 241.0687; found: 241.0690; Anal. Calcd for C15H12OS: C, 74.97; H, 5.03; S, 13.34. Found: C, 73.15; H, 4.99; S, 13.25.
1-Ethylsulfinyl-2-phenylacetylene (2b
2
). Obtained from thiadiazole 3b (R1 = Ph, 162 mg, 1 mmol) using ethyl iodide (R2 = Et, 0.4 mL, 5 mmol) as the electrophile gave 2b
2
as an orange oil. The product is highly unstable as previously reported in the literature (31 mg, 0.17 mmol, 17%); R
f
= 0.10 (PE-EtOAc, 4:1);
1H NMR (250 MHz, CDCl3): δ = 1.51 (t, J = 7.4 Hz, 3 H), 3.07-3.25 (m, 2 H), 7.34-7.92 (m, 5 H).
26a
Sklute G.
Marek I.
J. Am. Chem. Soc.
2006,
128:
4642
26b
Zhao SH.
Samuel O.
Kagan HB.
Tetrahedron
1987,
43:
5135
27a
Seybold G.
Heibl C.
Chem. Ber.
1977,
110-1225
27b
Butler RN.
O’Donoghue DA.
J. Chem. Soc., Perkin Trans 1
1982,
1223
27c
Rämsby SI.
Ögren SO.
Ross SB.
Stjernström NE.
Acta Pharm. Suecica
1973,
10:
285