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Volumn 15, Issue 39, 2009, Pages 10255-10262

Autocatalytic Enantiomerisation at the Crystal Surface in Deracemisation of Scalemic Conglomerates

Author keywords

Amplification; Asymmetric synthesis; Chiral resolution; Chirality; Crystal growth

Indexed keywords

ACHIRAL CATALYST; ASYMMETRIC SYNTHESIS; AUTOCATALYTIC; C-C BONDS; CHIRAL COMPOUNDS; CHIRAL PRODUCT; CHIRAL RESOLUTION; CHIRAL RESOLUTIONS; CRYSTAL SURFACES; ENANTIOMERIC EXCESS; ENANTIOPURE; HETEROGENEOUS SYSTEMS; ISOTHERMAL HEATING; KINETIC MODELS; LIFE-TIMES; PYRROLIDINES; ROOM TEMPERATURE; SATURATED SOLUTIONS; SMALL-SCALE EXPERIMENT; TEM;

EID: 70349686747     PISSN: 09476539     EISSN: 15213765     Source Type: Journal    
DOI: 10.1002/chem.200900979     Document Type: Article
Times cited : (43)

References (58)
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    • -1) for the racemic Mannich product, being in accord with the Meyerhoffer rule
    • -1) for the racemic Mannich product, being in accord with the Meyerhoffer rule: W. Meyerhoffer, Ber. Dtsch. Chem. Ges. 1904, 37, 2604.
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    • The cause of the gradual erosion of ee after reaching a maximum value could be the presence of competing reactions when the enan-tiomerisation is-in the absence of pyrrolidine-not effective enough.
    • The cause of the gradual erosion of ee after reaching a maximum value could be the presence of competing reactions when the enan-tiomerisation is-in the absence of pyrrolidine-not effective enough.
  • 19
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    • In a recent concept paper, Blackmond surmised that "homochirality could indeed result from a stagnant or slowly stirred state if a means of scaling the energy barrier" between the homochiral and the het-erochiral states is available. We doubt however, that this is viable, as thermal (dissipated)energy can easily be conceived to help surmount the activation barrier in kinetically controlled processes, but cannot maintain the required non-equilibrium state
    • In a recent concept paper, Blackmond surmised that "homochirality could indeed result from a stagnant or slowly stirred state if a means of scaling the energy barrier" between the homochiral and the het-erochiral states is available. We doubt however, that this is viable, as thermal (dissipated)energy can easily be conceived to help surmount the activation barrier in kinetically controlled processes, but cannot maintain the required non-equilibrium state: D. G. Blackmond, Chem. Eur. J. 2007, 13, 10306.
    • (2007) Chem. Eur. J. , vol.13 , pp. 10306
    • Blackmond, D.G.1
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    • Indeed, Vlieg and co-workers found that the chiral resolution with-out enantiomerisation and in the presence of a stereospecific additive is rather slow and takes more than 10 days for a 1.0 g batch.
    • Indeed, Vlieg and co-workers found that the chiral resolution with-out enantiomerisation and in the presence of a stereospecific additive is rather slow and takes more than 10 days for a 1.0 g batch.
  • 45
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    • A very similar idea has been proposed by us recently as a possible explanation for symmetry breaking in closed homogenous reversible reactive systems in which closed reaction networks could be operat-ed under open system conditions by coupling to irreversible side re-actions fuelling symmetry broken quasi-steady states, see
    • A very similar idea has been proposed by us recently as a possible explanation for symmetry breaking in closed homogenous reversible reactive systems in which closed reaction networks could be operat-ed under open system conditions by coupling to irreversible side re-actions fuelling symmetry broken quasi-steady states, see: M. Mauksch, S. B. Tsogoeva, ChemPhysChem 2008, 9, 2359.
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    • Mauksch, M.1    Tsogoeva, S.B.2
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    • This is similar to a statement in reference [22], referring though to the rate of enantiomerisation deep in the solution.
    • This is similar to a statement in reference [22], referring though to the rate of enantiomerisation deep in the solution.
  • 51
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    • We have also carried out a deracemisation experiment in a larger scale (1.2 g batch of product 1) in the presence of pyrrolidine and without abrasive grinding conditions. Complete deracemisation was achieved after one day, that is, longer than in the small-scale experi-ment, in accord with the observation that the deracemisation rate constant is proportional to the molality of the solid product as re-ported in reference [3d]. The yield obtained was very low (only 10%), with the majority (about two-third) of the side product being the reactant imine 2. This could underline that we either haven't found yet the most optimal conditions or the most promising reac-tion.
    • We have also carried out a deracemisation experiment in a larger scale (1.2 g batch of product 1) in the presence of pyrrolidine and without abrasive grinding conditions. Complete deracemisation was achieved after one day, that is, longer than in the small-scale experi-ment, in accord with the observation that the deracemisation rate constant is proportional to the molality of the solid product as re-ported in reference [3d]. The yield obtained was very low (only 10%), with the majority (about two-third) of the side product being the reactant imine 2. This could underline that we either haven't found yet the most optimal conditions or the most promising reac-tion.
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    • Only about 5-10% of all chiral compounds form conglomerates, which, hence, limits unfortunately the direct applicability of our method for broad practical use, see
    • Only about 5-10% of all chiral compounds form conglomerates, which, hence, limits unfortunately the direct applicability of our method for broad practical use, see: W. H. Porter, Pure Appl. Chem. 1991, 63, 1119.
    • (1991) Pure Appl. Chem. , vol.63 , pp. 1119
    • Porter, W.H.1
  • 53
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    • In recent years, though, methods have come forward in pharmaceutical technology and which allow the transformation of racemic compounds to racemic conglomerates when the thermody-namic requirements are met or by employing appropriate derivatisa-tion strategies, see
    • In recent years, though, methods have come forward in pharmaceutical technology and which allow the transformation of racemic compounds to racemic conglomerates when the thermody-namic requirements are met or by employing appropriate derivatisa-tion strategies, see: P. A. Levkin, E. Schweda, H.-J. KoIb, V. Schurig, R. G. Kostyanovski, Tetrahedron: Asymmetry 2004, 15, 1445.
    • (2004) Tetrahedron: Asymmetry , vol.15 , pp. 1445
    • Levkin, P.A.1    Schweda, E.2    Koib, H.-J.3    Schurig, V.4    Kostyanovski, R.G.5
  • 58
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    • The idea, that "asymmetric autocatalysis" could be involved in enantioselective formation of an oxo-rhenium(V) complex in pres-ence of "catalytic" amounts of the conglomerate product, was also recently put forward: see
    • The idea, that "asymmetric autocatalysis" could be involved in enantioselective formation of an oxo-rhenium(V) complex in pres-ence of "catalytic" amounts of the conglomerate product, was also recently put forward: see W. K. Rybak, Tetrahedron: Asymmetry 2008, 19, 2234.
    • (2008) Tetrahedron: Asymmetry , vol.19 , pp. 2234
    • Rybak, W.K.1


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.