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Volumn 13, Issue 6, 2011, Pages 1318-1321

Iterative stereospecific reagent-controlled homologation using a functionalized α-chloroalkyllithium: Synthesis of cyclic targets related to epibatidine

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EID: 79952605203     PISSN: 15237060     EISSN: 15237052     Source Type: Journal    
DOI: 10.1021/ol103170y     Document Type: Article
Times cited : (29)

References (42)
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    • For a definition of StReCH and elaboration of the generic attributes of this concept, see ref 2a.
    • For a definition of StReCH and elaboration of the generic attributes of this concept, see ref 2a.
  • 15
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    • For recent applications of the Matteson chain extension method, see: J. Organomet. Chem. 2000, 614-615, 314
    • For a substrate-controlled approach to synthesis based on iterative homologation of boronic esters, see ref 6a and: Matteson, D. S. Tetrahedron 1998, 54, 10555-10607 For recent applications of the Matteson chain extension method, see: Hiscox, W. C.; Matteson, D. S. J. Organomet. Chem. 2000, 614-615, 314
    • (1998) Tetrahedron , vol.54 , pp. 10555-10607
    • Matteson, D.S.1    Hiscox, W.C.2    Matteson, D.S.3
  • 17
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    • For seminal work concerning the generation of scalemic carbenoids via sulfoxide-ligand exchange, see: Hoffmann, R. W.; Nell, P. G.; Leo, R.; Harms, K. Chem.-Eur. J. 2000, 6, 3359-3365
    • (2000) Chem.-Eur. J. , vol.6 , pp. 3359-3365
    • Hoffmann, R.W.1    Nell, P.G.2    Leo, R.3    Harms, K.4
  • 21
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    • There are over 50 published syntheses of epibatidine. For recent efforts and a review, see: Lee, C.-L. K.; Loh, T.-P. Org. Lett. 2005, 7, 2965-2967
    • (2005) Org. Lett. , vol.7 , pp. 2965-2967
    • Lee, C.-L.K.1    Loh, T.-P.2
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    • Review: Org. Prep. Proced. Int. 2002, 34, 1-26
    • Bexrud, J.; Lautens, M. Org. Lett. 2010, 12, 3160-3163 Review: Olivo, H. F.; Hemenway, M. S. Org. Prep. Proced. Int. 2002, 34, 1-26
    • (2010) Org. Lett. , vol.12 , pp. 3160-3163
    • Bexrud, J.1    Lautens, M.2    Olivo, H.F.3    Hemenway, M.S.4
  • 33
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    • Previously, a combination of t -BuLi in PhMe had been regarded as optimal for the generation of α-chloroalkyllithiums via SLE (refs 2b, 16b); however, wary of the pyrophoric nature of t -BuLi, an alternative to this hazardous reagent was sought. It has now been discovered that PhLi, a reagent that presents significantly less risk, is superior to t -BuLi for SLE based StReCH chemistry. For recent examples of PhLi induced SLE, see
    • Previously, a combination of t -BuLi in PhMe had been regarded as optimal for the generation of α-chloroalkyllithiums via SLE (refs 2b, 16b); however, wary of the pyrophoric nature of t -BuLi, an alternative to this hazardous reagent was sought. It has now been discovered that PhLi, a reagent that presents significantly less risk, is superior to t -BuLi for SLE based StReCH chemistry. For recent examples of PhLi induced SLE, see: Ferrer, C.; Riera, A.; Verdaguer, X. Organometallics 2009, 28, 4571-4576
    • (2009) Organometallics , vol.28 , pp. 4571-4576
    • Ferrer, C.1    Riera, A.2    Verdaguer, X.3
  • 36
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    • Carbenoid 8a can decompose via a variety of pathways that do not lead to 14; this accounts for the lower isolated yield of 14 vs 13. See:, Lithiated sulfoxide 15 is likely also generated by direct deprotonation of 12 by PhLi. See: Tetrahedron Lett. 2007, 48, 3999-4002
    • Carbenoid 8a can decompose via a variety of pathways that do not lead to 14; this accounts for the lower isolated yield of 14 vs 13. See: Köbrich, G. Angew. Chem., Int. Ed. 1967, 6, 41-52 Lithiated sulfoxide 15 is likely also generated by direct deprotonation of 12 by PhLi. See: Blakemore, P. R.; Burge, M. S.; Sephton, M. A. Tetrahedron Lett. 2007, 48, 3999-4002
    • (1967) Angew. Chem., Int. Ed. , vol.6 , pp. 41-52
    • Köbrich, G.1    Blakemore, P.R.2    Burge, M.S.3    Sephton, M.A.4
  • 37
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    • Incomplete α-deuteration of the starting material used for entries 3 and 4, together with the expected faster H transfer from the minor H- 12 components, accounts in part for the generation of 14 as a mixture of all three (HH, HD, and DD) isotopomers. β-Elimination of HCl from 8a by the action of another 8a as base provides a second mechanism for proton transfer that could lead to HD- 14 from D- 12, see ref.
    • Incomplete α-deuteration of the starting material used for entries 3 and 4, together with the expected faster H transfer from the minor H- 12 components, accounts in part for the generation of 14 as a mixture of all three (HH, HD, and DD) isotopomers. β-Elimination of HCl from 8a by the action of another 8a as base provides a second mechanism for proton transfer that could lead to HD- 14 from D- 12, see ref.
  • 38
    • 79952603071 scopus 로고    scopus 로고
    • For a given configuration at sulfur, syn and anti α - chlorosulfoxides lead to opposite carbenoid enantiomers upon SLE. Thus, in the case of entry 3 (Table 2), a product ee no higher than 90% should be expected given that the dr of the carbenoid source was 95:5.
    • For a given configuration at sulfur, syn and anti α- chlorosulfoxides lead to opposite carbenoid enantiomers upon SLE. Thus, in the case of entry 3 (Table 2), a product ee no higher than 90% should be expected given that the dr of the carbenoid source was 95:5.
  • 39
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    • 2 + 1):(2 × 19) = 90.5:9.5. For an early description of this kind of effect, see
    • 2 + 1):(2 × 19) = 90.5:9.5. For an early description of this kind of effect, see: Vigneron, J. P.; Dhaenens, M.; Horeau, A. Tetrahedron 1973, 29, 1055-1059
    • (1973) Tetrahedron , vol.29 , pp. 1055-1059
    • Vigneron, J.P.1    Dhaenens, M.2    Horeau, A.3
  • 40
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    • Related protodeboronations from benzylic positions were recently reported
    • Related protodeboronations from benzylic positions were recently reported: Nave, S.; Sonawane, R. P.; Elford, T. G.; Aggarwal, V. K. J. Am. Chem. Soc. 2010, 132, 17096-17098
    • (2010) J. Am. Chem. Soc. , vol.132 , pp. 17096-17098
    • Nave, S.1    Sonawane, R.P.2    Elford, T.G.3    Aggarwal, V.K.4
  • 42
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    • A pinacol-type reductive cyclization of 23 could lead directly to 5-oxyepibatidines. 5-Hydroxyepibatidines show selective binding affinity for nAChR subtypes; see
    • A pinacol-type reductive cyclization of 23 could lead directly to 5-oxyepibatidines. 5-Hydroxyepibatidines show selective binding affinity for nAChR subtypes; see: Wei, Z.-L.; Xiao, Y.; George, C.; Kellar, K. J.; Kozikowski, A. P. Org. Biorg. Chem. 2003, 1, 3878-3881
    • (2003) Org. Biorg. Chem. , vol.1 , pp. 3878-3881
    • Wei, Z.-L.1    Xiao, Y.2    George, C.3    Kellar, K.J.4    Kozikowski, A.P.5


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.