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Synlett
Volumn , Issue 1, 2009, Pages 28-31
Thieme Chemistry Journal Awardees - Where are they now? Regio- and stereoselective radical additions of thiols to ynamides
Author keywords

Hydrogenation; Hydrothiolation; Radical; Ynamide
Indexed keywords

EID: 62349134364     PISSN: 09365214     EISSN: 14372096     Source Type: Journal    
DOI: 10.1055/s-0028-1087379     Document Type: Article
Times cited : (47)
References (45)
  • 9
  • 22
    • 0007758383 scopus 로고
    • For boron-substituted alkynes, see: a
    • For boron-substituted alkynes, see: (a) Matteson, D. S.; Peacock, K. J. Org. Chem. 1963, 28, 369.
    • (1963) J. Org. Chem , vol.28 , pp. 369
    • Matteson, D.S.1    Peacock, K.2
  • 27
    • 0346656516 scopus 로고    scopus 로고
    • For the first example of a radical reaction involving ynamides, see
    • For the first example of a radical reaction involving ynamides, see: Marion, F.; Courillon, C.; Malacria, M. Org. Lett. 2003, 5, 5095.
    • (2003) Org. Lett , vol.5 , pp. 5095
    • Marion, F.1    Courillon, C.2    Malacria, M.3
  • 28
    • 58149310515 scopus 로고    scopus 로고
    • Our group has reported the hydrothiolation of ynamides with dithiophosphinic acid via cationic intermediates: Kanemura, S, Kondoh, A, Yasui, H, Yorimitsu, H, Oshima, K. Bull. Chem. Soc. Jpn. 2008, 81, 506
    • Our group has reported the hydrothiolation of ynamides with dithiophosphinic acid via cationic intermediates: Kanemura, S.; Kondoh, A.; Yasui, H.; Yorimitsu, H.; Oshima, K. Bull. Chem. Soc. Jpn. 2008, 81, 506.
  • 29
    • 84987243527 scopus 로고    scopus 로고
    • For examples of the synthesis of (Z)-1-amino-2-thio-1-alkene derivatives, see: (a) Apparao, S, Schmidt, R. R. Synthesis 1987, 896
    • For examples of the synthesis of (Z)-1-amino-2-thio-1-alkene derivatives, see: (a) Apparao, S.; Schmidt, R. R. Synthesis 1987, 896.
  • 31
    • 0033538289 scopus 로고    scopus 로고
    • For hydrothiolations under transition-metal catalysis, see: a
    • For hydrothiolations under transition-metal catalysis, see: (a) Ogawa, A.; Ikeda, T.; Kimura, K.; Hirao, T. J. Am. Chem. Soc. 1999, 121, 5108.
    • (1999) J. Am. Chem. Soc , vol.121 , pp. 5108
    • Ogawa, A.1    Ikeda, T.2    Kimura, K.3    Hirao, T.4
  • 37
    • 62349121064 scopus 로고    scopus 로고
    • Typical Experimental Procedure for Radical Hydrothiolation of Ynamides: Under air, Et3B (1.0 M hexane solution, 0.050 mL, 0.050 mmol) was added to a solution of N-benzyl-N-(1-octynyl)-p-toluenesulfonamide (1a, 0.18 g, 0.50 mmol) and benzenethiol (2a, 0.062 mL, 0.60 mmol) in CH2Cl2 (2.0 mL) at -30°C. The solution was stirred for 30 min at the same temperature and concentrated in vacuo. 1H NMR analysis of the crude mixture showed a 94% yield of the adduct (Z/E >99:1, Silica gel column chromatography (hexane-EtOAc, 10:1 → 5:1) afforded N-benzyl-N, Z)-2- phenylthio-1-octenyl]-p-toluenesulfonamide (3aa) as a white solid in 89% yield (0.21 g, 0.45 mmol, 3aa: IR (Nujol, 2925, 1456, 1351, 1339, 1161, 1089, 1024, 741, 661 cm-1. 1H NMR (CDCl 3, δ, 0.83 (t, J, 7.5 Hz, 3 H, 1.02-1.15 (m, 4 H, 1.16-1.35 m
    • 2: C, 70.11; H, 6.93. Found: C, 70.00; H, 6.94.
  • 38
    • 37049087867 scopus 로고    scopus 로고
    • It was reported that arylthiyl radicals behave as electron-deficient radicals: Ito, O.; Fleming, M. D. C. M. J. Chem. Soc., Perkin Trans. 2 1989, 689.
    • It was reported that arylthiyl radicals behave as electron-deficient radicals: Ito, O.; Fleming, M. D. C. M. J. Chem. Soc., Perkin Trans. 2 1989, 689.
  • 39
    • 62349129003 scopus 로고    scopus 로고
    • The diastereoselectivity can be explained by steric effect. In reference 4b, Montevecci and Spagnolo insisted that primary alkyl groups are bulkier than a phenylthio group. We thus assume that vinyl radical 5 would exist almost as a Z-form to prevent the steric repulsion between the bulky amide moiety and the alkyl group. The Z-form abstracts hydrogen from benzenethiol selectively. On the other hand, Montevecci et al. also insisted that a methyl group is smaller than a phenylthio group. Indeed, the reaction of N-methyl-N-(1-propenyl)-p-toluenesulfonamide with benzenethiol resulted in favorable formation of the corresponding Z-adduct (E/Z = 2:3).
    • The diastereoselectivity can be explained by steric effect. In reference 4b, Montevecci and Spagnolo insisted that primary alkyl groups are bulkier than a phenylthio group. We thus assume that vinyl radical 5 would exist almost as a Z-form to prevent the steric repulsion between the bulky amide moiety and the alkyl group. The Z-form abstracts hydrogen from benzenethiol selectively. On the other hand, Montevecci et al. also insisted that a methyl group is smaller than a phenylthio group. Indeed, the reaction of N-methyl-N-(1-propenyl)-p-toluenesulfonamide with benzenethiol resulted in favorable formation of the corresponding Z-adduct (E/Z = 2:3).
  • 40
    • 62349107145 scopus 로고    scopus 로고
    • The addition reaction of phenyl-substituted ynamide PhC≡CNTs(Bn) led to a mixture of stereo- and regioisomers
    • The addition reaction of phenyl-substituted ynamide PhC≡CNTs(Bn) led to a mixture of stereo- and regioisomers.
  • 42
    • 62349084990 scopus 로고    scopus 로고
    • Typical Experimental Procedure for Hydrogenations of the Double Bonds of Enamides: Under an argon atmosphere, Et3SiH (0.048 mL, 0.30 mmol) was added to a solution of 3aa (0.096 g, 0.20 mmol) in TFA (1.0 mL, 13.5 mmol) at 0°C. The solution was stirred for 11 h at the same temperature. Then the reaction was quenched with a sat. NaHCO3 solution and extracted with EtOAc (2 x 10 mL, The organic extracts were dried over Na2SO4 and concentrated in vacuo. Silica gel column chromatography (hexane-EtOAc, 20:1) afforded N-benzyl-N-[2, phenylthio)-octyl]-p-toluenesulfonamide (6aa) as a colorless oil in 87% yield (0.084 g, 0.17 mmol, 6aa: IR (neat, 2926, 2855, 1599, 1456, 1439, 1342, 1162, 1092, 737, 654 cm-1. 1H NMR (CDCl3, δ, 0.88 (t, J, 7.5 Hz, 3 H, 1.02-1.31 (m, 8 H, 1.34-1.46 (m, 1 H, 1.65-1.75 (m, 1 H, 2.42 (s, 3 H, 2.95-3.05 m, 2 H, 3.26
    • 2: C, 69.81; H, 7.32. Found: C, 70.03; H, 7.38.
  • 44
    • 36448987908 scopus 로고    scopus 로고
    • Chiral vic-aminothio compounds serve as ligands in enantioselective reactions. See: (a) Vargas, F.; Sehnem, J. A.; Galetto, F. Z.; Braga, A. L. Tetrahedron 2008, 64, 392; and references cited therein.
    • Chiral vic-aminothio compounds serve as ligands in enantioselective reactions. See: (a) Vargas, F.; Sehnem, J. A.; Galetto, F. Z.; Braga, A. L. Tetrahedron 2008, 64, 392; and references cited therein.

* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.