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Volumn 47, Issue 15, 2008, Pages 2869-2871

Hydride shift generated oxonium ions: Evidence for mechanism and intramolecular trapping experiments to form trans THF derivatives

Author keywords

Hydride shift; Oxonium ion; Reduction; Stereoselectivity; Synthetic methods

Indexed keywords

CHEMICAL REACTIONS; ORGANIC COMPOUNDS; ORGANOMETALLICS; STEREOCHEMISTRY;

EID: 42249089076     PISSN: 14337851     EISSN: None     Source Type: Journal    
DOI: 10.1002/anie.200705340     Document Type: Article
Times cited : (25)

References (20)
  • 1
    • 33845238277 scopus 로고    scopus 로고
    • For a review of methods for making THF rings, see
    • For a review of methods for making THF rings, see: J. P. Wolfe, M. B. Hay, Tetrahedron 2007, 63, 261.
    • (2007) Tetrahedron , vol.63 , pp. 261
    • Wolfe, J.P.1    Hay, M.B.2
  • 3
    • 23044503924 scopus 로고    scopus 로고
    • Angew. Chem. Int. Ed. 2005, 44, 4766-4768.
    • (2005) Angew. Chem. Int. Ed , vol.44 , pp. 4766-4768
  • 5
    • 34548682314 scopus 로고    scopus 로고
    • For a general review of oxidative cyclization by metal oxo species, see
    • For a general review of oxidative cyclization by metal oxo species, see: V. Piccialli, Synthesis 2007, 2585.
    • (2007) Synthesis , pp. 2585
    • Piccialli, V.1
  • 11
    • 2242470784 scopus 로고
    • for ring expansion reactions of secondary mesylates derived from oxidative cyclization, see
    • e) for ring expansion reactions of secondary mesylates derived from oxidative cyclization, see: R. C. D. Brown, P. J. Kocienski, Synlett 1994, 415.
    • (1994) Synlett , pp. 415
    • Brown, R.C.D.1    Kocienski, P.J.2
  • 12
    • 53549098439 scopus 로고    scopus 로고
    • The analogue of compound 5, which is diastereomeric at the OMs center, returned starting material under the reaction conditions. This stereoelectronic effect can be considered to be further evidence for a concerted hydride shift/OMs displacement, because the reactive conformation (C-H and C-OMs antiperiplanar) suffers from undue steric hinderance between the sidechain and the THF ring: this strain is reduced with its diastereoisomer 5.
    • The analogue of compound 5, which is diastereomeric at the OMs center, returned starting material under the reaction conditions. This stereoelectronic effect can be considered to be further evidence for a concerted hydride shift/OMs displacement, because the reactive conformation (C-H and C-OMs antiperiplanar) suffers from undue steric hinderance between the sidechain and the THF ring: this strain is reduced with its diastereoisomer 5.
  • 13
    • 53549105414 scopus 로고    scopus 로고
    • We do not assume concomitant attack of acetate anion and loss of hydride from the silicon. Removal of the silyl group that is generated by this mechanism, as shown in Scheme 3, is straightforward using tetra-n-butylammonium fluoride (TBAF, For related directed ionic hydrogenation reactions, see: a) S. Anwar, G. Bradley, A. P. Davis, J. Chem. Soc. Perkin Trans. 1 1991, 1381;
    • We do not assume concomitant attack of acetate anion and loss of hydride from the silicon. Removal of the silyl group that is generated by this mechanism, as shown in Scheme 3, is straightforward using tetra-n-butylammonium fluoride (TBAF). For related directed ionic hydrogenation reactions, see: a) S. Anwar, G. Bradley, A. P. Davis, J. Chem. Soc. Perkin Trans. 1 1991, 1381;
  • 18
    • 0033616106 scopus 로고    scopus 로고
    • 3SiH) onto oxonium ions such as A gives predominantly the cis diastereoisomer, presumably for steric reasons; see also Scheme 6. For the influence that substituents within the THF ring can have on oxonium ion trapping, see: a) C. H. Larsen, B. H. Ridgway, J. T. Shaw, K. A. Woerpel, J. Am. Chem. Soc. 1999, 121, 12208;
    • 3SiH) onto oxonium ions such as A gives predominantly the cis diastereoisomer, presumably for steric reasons; see also Scheme 6. For the influence that substituents within the THF ring can have on oxonium ion trapping, see: a) C. H. Larsen, B. H. Ridgway, J. T. Shaw, K. A. Woerpel, J. Am. Chem. Soc. 1999, 121, 12208;
  • 20
    • 34347245264 scopus 로고    scopus 로고
    • Angew. Chem. Int. Ed. 2007, 46, 4693-4697.
    • (2007) Angew. Chem. Int. Ed , vol.46 , pp. 4693-4697


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