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DOI: 10.1055/s-2008-1078030
Diastereoselective Thia-Claisen Rearrangement of Pyrrolidinone-Derived Ketene N,S-Acetals
Publication History
Publication Date:
05 August 2008 (online)
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Abstract
Thia-Claisen rearrangements of S-allylic ketene N,S-acetals were carried out using substrates with an external allylic stereogenic centre. High levels of diastereoselectivity were observed only when a bromine substituent was introduced onto the double bond.
Key words
sulfur - bromine - diastereoselectivity - pericyclic reactions - rearrangements
- 1
Castro AM. Chem. Rev. 2004, 104: 2939 - For reviews of asymmetric [3,3]-sigmatropic rearrangements, see:
-
2a
Enders D.Knopp M.Schiffers R. Tetrahedron: Asymmetry 1996, 7: 1847 -
2b
Ito H.Taguchi T. Chem. Soc. Rev. 1999, 29: 43 -
2c
Nubbemeyer U. Synthesis 2003, 961 -
3a
Suzuki T.Sato E.Kamada S.Tada H.Unno K.Kametani T. J. Chem. Soc., Perkin Trans. 1 1986, 387 -
3b
Takano S.Kurotaki A.Takahashi M.Ogasawara K. J. Chem. Soc., Perkin Trans. 1 1987, 91 -
3c
Nemoto H.Satoh A.Ando M.Fukumoto K. J. Chem. Soc., Perkin Trans. 1 1991, 1309 - 4
Hatakeyama S.Saijo K.Takano S. Tetrahedron Lett. 1985, 26: 865 - 5
Tadano K.Minami M.Ogawa S. J. Org. Chem. 1990, 55: 2108 - 6
Cha JK.Lewis SC. Tetrahedron Lett. 1984, 25: 5263 - 7
Désert S.Metzner P. Tetrahedron 1992, 48: 10327 - 8
Mulzer J.Shanyoor M. Tetrahedron Lett. 1993, 34: 6545 - High levels of asymmetric induction have also been observed in zwitterionic Claisen-type rearrangements involving either sulfide-ketene adducts or deprotonated N-acylammonium salts. See:
-
9a
Nubbemeyer U.Öhrlein R.Gonda J.Ernst B.Bellu D. Angew. Chem., Int. Ed. Engl. 1991, 30: 1465 -
9b
Nubbemeyer U. J. Org. Chem. 1996, 61: 3677 -
10a
Takano S.Hirama M.Ogasawara K. Chem. Lett. 1982, 11: 529 -
10b
Tamaru Y.Furukawa Y.Mizutani M.Kitao O.Yoshida Z. J. Org. Chem. 1983, 48: 3631 -
10c
Mortimer AJP.Pang PS.Aliev AE.Tocher DA.Porter MJ. Org. Biomol. Chem. 2008, 6: DOI: 10.1039/b806031b - 11
Marshall JA.Trometer JD.Cleary DG. Tetrahedron 1999, 45: 391 - 12
Borcherding DR.Narayanan S.Hasobe M.McKee JG.Keller BT.Borchardt RT. J. Med. Chem. 1988, 31: 1729 - 13
Hoffmann RW. Chem. Rev. 1989, 89: 1841 - 14
McKenna CE.Khawli LA. J. Org. Chem. 1986, 51: 5467 - 17
Zhong YL.Shing TKM. J. Org. Chem. 1997, 62: 2622 - 19
Rossi R.Bellina F.Raugei E. Synlett 2000, 1749 - 20
Scott WJ.Stille JK. J. Am. Chem. Soc. 1986, 108: 3033 -
21a
Chérest M.Felkin H.Prudent N. Tetrahedron Lett. 1968, 2199 -
21b
Anh NT.Eisenstein O. Tetrahedron Lett. 1976, 155 -
21c
Anh NT. Top. Curr. Chem. 1980, 88: 145 - 22
Kahn SD.Hehre WJ. J. Org. Chem. 1988, 53: 301
References and Notes
A mixture of thioamide 15 (116 mg, 0.61 mmol), bromide 14b (200 mg, 0.67 mmol), MeCN (1 mL) and 4 Å molecular sieves (250 mg) was stirred under an argon atmosphere for 4 d. Further MeCN (2 mL) was added and the mixture warmed to 35 ˚C. Et3N (94 µL, 0.67 mmol) was added and the resulting solution was stirred at 35 ˚C for 7 h. The mixture was cooled to r.t., diluted with CH2Cl2 (30 mL) and washed with 2% citric acid (2 × 50 mL). The combined aqueous washings were extracted with CH2Cl2 (50 mL), and the combined organic layers were dried (MgSO4) and concentrated in vacuo to give the crude product (190 mg, 76%). Flash chromatography (SiO2; EtOAc-PE, 1:19) afforded 18b (130 mg, 52%) as a pale yellow oil; Rf 0.43 (EtOAc-PE, 15:85); [α]D ²0 +31.5 (c = 1.08, CHCl3). IR (CHCl3 cast): 2983, 2934, 2874 (CH), 1625 (C=C), 1499, 1452, 1316 (C=S) cm-¹. ¹H NMR (500 MHz, CDCl3): δ = 1.28 (3 H, s) and 1.34 [3 H, s, C(CH3)2], 2.30-2.40 (2 H, m, NCH2CH 2), 3.21 (1 H, br t, J = 8.5 Hz, CHC=S), 3.51 (1 H, ddd, J = 11.0, 8.5, 7.0 Hz) and 3.62 (1 H, ddd, J = 11.0, 8.8, 5.2 Hz, NCH 2CH2), 3.76 (1 H, dd, J = 8.5, 6.8 Hz, CHHO), 3.88 [1 H, dd, J = 10.1, 1.8 Hz, H2C=C(Br)CH], 4.10 (1 H, dd, J = 8.5, 6.1 Hz, CHHO), 4.44 (1 H, ddd, J = 10.1, 6.8, 6.1 Hz, CHO), 4.79 (1 H, d, J = 14.6 Hz) and 5.16 (1 H, d, J = 14.6 Hz, PhCH 2), 5.51 (1 H, dd, J = 1.8, 0.5 Hz) and 5.90 (1 H, dd, J = 1.8, 0.4 Hz, C=CH2), 7.26-7.32 (5 H, m, ArH). ¹³C NMR (125 MHz, CDCl3): δ = 22.2 (NCH2 CH2), 26.0 and 26.5 [C(CH3)2], 51.9 (PhCH2), 52.8 (NCH2CH2), 55.2 [H2C=C(Br)CH], 56.9 (CHC=S), 68.7 (CH2O), 74.7 (CHO), 110.1 [C(CH3)2], 119.8 (C=CH2), 127.9, 128.2 and 128.7 (aromatic CH), 133.5 (C=CH2), 135.3 (aromatic C), 203 (C=S). MS (CI+, CH4): m/z = 410 (16), 412 (14) [MH+], 352 (46), 354 (50) [MH+ - Me2CO], 338 (63), 330 (100) [MH+ - HBr]. HRMS: m/z [MH+] calcd for C19H25 79BrNO2S: 410.0789; found: 410.0799.
16X-ray data: C16H21NO2S, M = 291.40; T = 150(2) K; orthorhombic, P212121, a = 8.6108(10), b = 13.2760(16), c = 13.3204(16) Å; Z = 4; D c = 1.271 g/cm³; F(000) = 624; µ(Μο-Κα) = 0.214 mm-¹; 12892 reflection, 3586 independent (R int = 0.0336) measured on a Bruker SMART APEX CCD diffractometer using Μο-Κα radiation; R1 = 0.0350, wR2 = 0.0834 (3346 reflections F ² >2σ F ²), R1 = 0.0382, wR2 = 0.0855 (all data). Atomic coordinates and further crystallographic details have been deposited at the Cambridge Crystallographic Data Centre, deposition number CCDC 687669. Copies of these data can be obtained by applying to CCDC, University Chemical Laboratory, Lensfield Road, Cambridge CB2 1EW, U.K.; fax: +44 (1223)336033; email: deposit@ccdc.cam.ac.uk.
18Data for 21: Rf
0.23 (EtOAc-PE,
30:70); [α]D
²0 -73.2
(c = 0.40, CHCl3).
IR (CHCl3 cast): 3399 (br, OH), 2923, 2875 (CH), 1635
(C=C), 1508, 1453, 1310 (C=S) cm-¹. ¹H
NMR (500 MHz, CDCl3): δ = 1.87 (1 H,
ddt, J = 12.8, 8.8, 6.1 Hz) and
2.17 (1 H, dtd, J = 12.8, 9.1,
5.9 Hz, NCH2CH
2),
2.62 (1 H, br s, OH), 3.02 (1
H, m, H2C=CHCH), 3.33 (1 H, ddd, J = 9.1, 6.3, 3.6 Hz, CHC=S),
3.44 (1 H, ddd, J = 11.2, 9.1, 6.1
Hz) and 3.49 (1 H, ddd, J = 11.2,
8.8, 5.9 Hz, NCH
2CH2), 3.71
(1 H, dd, J = 11.5, 6.5 Hz)
and 3.84 (1 H, dd, J = 11.5, 9.1
Hz, CH
2OH), 4.90 (1 H, d, J = 14.3 Hz) and 5.05 (1 H,
d, J = 14.3 Hz, PhCH
2), 5.10 (1 H, dd, J = 10.5, 1.8 Hz) and 5.20 (1
H, dd, J = 17.3,
1.8 Hz, CH=CH
2), 5.64 (1
H, ddd, J = 17.3, 10.5, 8.8
Hz, CH=CH2), 7.28-7.34
(5 H, m, ArH). ¹³C NMR (125 MHz, CDCl3): δ = 23.1
(NCH2
CH2), 49.3 (H2C=CHCH), 51.8 (PhCH2),
52.8 (NCH2CH2),
55.1 (CHC=S), 63.0 (CH2OH),
118.4 (CH=CH2), 128.1,
128.3 and 128.8 (aromatic CH), 134.9 (aromatic C), 135.6 (CH=CH2), 202.7 (C=S). MS (CI+, CH4): m/z = 290 (22) [M + C2H5]+,
262 (100) [MH+], 244 (32) [MH+ - H2O],
191 (25). HRMS: m/z [M + H+] calcd
for C15H20NOS: 262.1266; found: 262.1260.
For 22: [α]D
²0 +71.4
(c = 0.28, CHCl3).
An alternative explanation is that both products arise from transition states in which the methine C-H bond of the acetonide eclipses the double bond, but the selectivity for reaction anti to the allylic C-O bond is imperfect. Such an explanation, however, does not account for the difference between the brominated and nonbrominated substrates.