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Volumn 687, Issue 2, 2003, Pages 525-537

2H-quadrupolar coupling-based analysis of stereochemical and regiochemical memory in the Pd-catalysed allylic alkylation of iso-cinnamyl type substrates employing the chiral monophosphine ligands 'MOP' and 'MAP'

Author keywords

2H NMR; Asymmetric catalysis; Liquid crystals; Memory effects; Palladium

Indexed keywords

ACETIC ACID; ALLYL COMPOUND; ANION; CINNAMIC ACID DERIVATIVE; DEUTERIUM; ESTER; MALONIC ACID; NAPHTHALENE DERIVATIVE; PALLADIUM; PHOSPHINE DERIVATIVE; SODIUM DERIVATIVE;

EID: 0344012070     PISSN: 0022328X     EISSN: None     Source Type: Journal    
DOI: 10.1016/j.jorganchem.2003.09.015     Document Type: Article
Times cited : (34)

References (57)
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    • For a very recent review see
    • For a very recent review see: B.M. Trost, M.L. Crawley, Chem. Rev. 103 (2003) 2921.
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    • 2-Pd-p[C(3)=C(2)]-C(1) or η2-Pd-p-[C(1)=C(2)]-C(3) alkene complex respectively. For discussions see
    • 2-Pd-p[C(3)=C(2)]-C(1) or η2-Pd-p-[C(1)=C(2)]-C(3) alkene complex respectively. For discussions see: A. Pfaltz, Acta Chem. Scand. 50 (1996) 189
    • (1996) Acta Chem. Scand. , vol.50 , pp. 189
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    • In the case of non-allylic intermediates, and in particular with Ni, interactions of type III have been cited as important factors in control of reactivity and selectivity through ligand hemilability. Interactions of type II may have been overlooked, see:
    • In the case of non-allylic intermediates, and in particular with Ni, interactions of type III have been cited as important factors in control of reactivity and selectivity through ligand hemilability. Interactions of type II may have been overlooked, see: Nandi M. Jin J. RajanBabu T.V. J. Am. Chem. Soc. 121 1999 9899
    • (1999) J. Am. Chem. Soc. , vol.121 , pp. 9899
    • Nandi, M.1    Jin, J.2    RajanBabu, T.V.3
  • 39
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    • For a review of the coordination of axially chiral bidentate based ligands such as MOP (2), MAP (3) and relatives, see:
    • For a review of the coordination of axially chiral bidentate based ligands such as MOP (2), MAP (3) and relatives, see: McCarthy M. Guiry P.J. Tetrahedron 57 2001 3809
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    • McCarthy, M.1    Guiry, P.J.2
  • 41
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    • -1 morestable than 8b (DFT calculations were performed using the B3LYP basis set and executed through the SPARTAN interface)
    • -1 morestable than 8b (DFT calculations were performed using the B3LYP basis set and executed through the SPARTAN interface)
    • (1998) Pure Appl. Chem. , vol.70 , pp. 1035
    • Prétôt, R.1    Lloyd-Jones, G.C.2    Pfaltz, A.3
  • 45
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    • 1H-NMR became crowded by non-alkene signals on attempting a conventional paramagnetic chiral shift reagent analysis
    • 1H-NMR became crowded by non-alkene signals on attempting a conventional paramagnetic chiral shift reagent analysis.
  • 47
    • 0037438418 scopus 로고    scopus 로고
    • For a recent application of this technique to the study mechanistic issues see
    • For a recent application of this technique to the study mechanistic issues see: O'Hagan D. Goss R.J.M. Meddour A. Courtieu J. J. Am. Chem. Soc. 125 2003 379
    • (2003) J. Am. Chem. Soc. , vol.125 , pp. 379
    • O'Hagan, D.1    Goss, R.J.M.2    Meddour, A.3    Courtieu, J.4
  • 49
    • 0345584257 scopus 로고    scopus 로고
    • g we observe in 9a (72% ee) is slightly higher than the value of 68% reported by Hayashi et al. [16]. This self consistent deviation suggests that under our conditions we experience slightly more equilibration
    • g we observe in 9a (72% ee) is slightly higher than the value of 68% reported by Hayashi et al. [16]. This self consistent deviation suggests that under our conditions we experience slightly more equilibration.
  • 50
    • 0345152406 scopus 로고    scopus 로고
    • g values can be used directly calculate matched and mismatched enantioselectivities without need for regioisomeric weighting
    • g values can be used directly calculate matched and mismatched enantioselectivities without need for regioisomeric weighting.
  • 51
    • 0345152407 scopus 로고    scopus 로고
    • Unlike MAP ( 3), it seems that with MOP ( 2), a bidentate P,C-coordination may be especially favoured with small allyl units such as π-allyl or π-cycloalkenyl
    • Unlike MAP ( 3), it seems that with MOP ( 2), a bidentate P,C-coordination may be especially favoured with small allyl units such as π-allyl or π-cycloalkenyl.
  • 53
    • 0344722053 scopus 로고    scopus 로고
    • N2-type displacement of the allyl unit, thereby facilitating diastereofacial exchange, is ruled out by the stereospecificity observed in the reactions
    • N2-type displacement of the allyl unit, thereby facilitating diastereofacial exchange, is ruled out by the stereospecificity observed in the reactions.
  • 54
    • 0344290108 scopus 로고    scopus 로고
    • 3-C) losingx their favourable trans relationships
    • 3-C) losingx their favourable trans relationships.
  • 55
    • 0345584256 scopus 로고    scopus 로고
    • The memory effect and stereospecific nature of the Pd-catalysed reaction allow one to deduce which of the two intermediates is attacked preferentially since nucleophilic attack trans to the phosphine in 11′ gives rise to the observed major enantiomer of product ((R)- 9a). Crucial to this analysis is that the analogous complexes where the Ph ring is in the anti position (as opposed to the syn position in 11 and 11′) are not involved. Acyclic allyl complexes with solely anti-located substituent are rare. Support for this comes from the geometry of the isolated acetate complex ( 12/ 13) where Ph is in the syn position in the major regioisomer-see Ref. [16] and the lack of cis isomers of 8a evident in the product mixtures
    • The memory effect and stereospecific nature of the Pd-catalysed reaction allow one to deduce which of the two intermediates is attacked preferentially since nucleophilic attack trans to the phosphine in 11′ gives rise to the observed major enantiomer of product ((R)- 9a). Crucial to this analysis is that the analogous complexes where the Ph ring is in the anti position (as opposed to the syn position in 11 and 11′) are not involved. Acyclic allyl complexes with solely anti-located substituent are rare. Support for this comes from the geometry of the isolated acetate complex ( 12/ 13) where Ph is in the syn position in the major regioisomer-see Ref. [16] and the lack of cis isomers of 8a evident in the product mixtures.
  • 56
    • 0344290110 scopus 로고    scopus 로고
    • It is noted that the opposite argument that the more strained and less favoured regioisomer ( 10/ 10′) would be attacked preferentially under equilibrium conditions has to be invoked when the regiochemical outcome is considered. Of course, the two allyl termini are not equivalent and thus further factors must also be considered, including: (i) a greater steric interaction between nucleophile and allyl group is expected on attack of 11/ 11′ adjacent to the Ph ring; and (ii) the products are not degenerate and 8a is thermodynamically more favoured since the alkene unit is disubstituted and conjugated with the Ph ring
    • It is noted that the opposite argument that the more strained and less favoured regioisomer ( 10/ 10′) would be attacked preferentially under equilibrium conditions has to be invoked when the regiochemical outcome is considered. Of course, the two allyl termini are not equivalent and thus further factors must also be considered, including: (i) a greater steric interaction between nucleophile and allyl group is expected on attack of 11/ 11′ adjacent to the Ph ring; and (ii) the products are not degenerate and 8a is thermodynamically more favoured since the alkene unit is disubstituted and conjugated with the Ph ring.


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