Mirror-symmetry breaking in the Soai reaction: a kinetic understanding.

Kinetic modeling using nonlinear differential equations is proposed to analyze the spontaneous generation of enantiomeric excess in the autocatalytic addition of diisopropylzinc to prochiral pyrimidine carbaldehydes (Soai reaction). Our approach reproduces experimentally observed giant chiral amplification from an initial enantiomeric excess of <10(-6)% to >60%, high sensitivity and positive response to the presence of minute amounts of chiral initiator at concentrations <10(-14) M, and spontaneous absolute asymmetric synthesis from achiral starting conditions. From our numerical simulations using kinetic schemes derived from the Frank model, including stereospecific autocatalysis and mutual inhibition, we have shown that it is possible to reproduce the mirror-symmetry-breaking behavior of the Soai reaction under batch conditions leading to a bimodal enantiomeric product distribution. Mirror-symmetry breaking was found to be resistant to a loss of stereoselectivity up to 30%. While the mutual inhibition between enantiomers seems to originate from the presence of dimerization equilibria, the exact nature of the autocatalytic stereoselective process still remains to be revealed. From the kinetic viewpoint, simple autocatalysis involving monomers as the catalytic species is consistent with all reported experimental effects of the Soai reaction.

[1]  Christian Girard,et al.  Nonlinear Effects in Asymmetric Synthesis and Stereoselective Reactions: Ten Years of Investigation. , 1998, Angewandte Chemie.

[2]  R. Delden,et al.  Absolute Asymmetric Synthesis: The Origin, Control, and Amplification of Chirality. , 1999, Angewandte Chemie.

[3]  John M. Brown,et al.  Solution structure and reagent binding of the zinc alkoxide catalyst in the Soai asymmetric autocatalytic reaction. , 2004, Angewandte Chemie.

[4]  D. Kondepudi,et al.  Chiral-symmetry-breaking states and their sensitivity in nonequilibrium chemical systems , 1984 .

[5]  Kenso Soai,et al.  Asymmetric synthesis of pyrimidyl alkanol without adding chiral substances by the addition of diisopropylzinc to pyrimidine-5-carbaldehyde in conjunction with asymmetric autocatalysis , 2003 .

[6]  I. Prigogine,et al.  Book Review: Modern Thermodynamics: From Heat Engines to Dissipative Structures , 1998 .

[7]  D. Blackmond,et al.  Kinetic evidence for a tetrameric transition state in the asymmetric autocatalytic alkylation of pyrimidyl aldehydes. , 2003, Journal of the American Chemical Society.

[8]  Dietmar Seyferth,et al.  Comprehensive Organometallic Chemistry , 1984 .

[9]  K. Tsukiyama,et al.  Relationship between the time, yield, and enantiomeric excess of asymmetric autocatalysis of chiral 2-alkynyl-5-pyrimidyl alkanol with amplification of enantiomeric excess , 2003 .

[10]  K. Soai,et al.  Asymmetric synthesis utilizing circularly polarized light mediated by the photoequilibrium of chiral olefins in conjunction with asymmetric autocatalysis. , 2004, Angewandte Chemie.

[11]  R. Noyori,et al.  Homochiral and heterochiral dimers of the methylzinc alkoxide formed from dimethylzinc and enantiomeric 3-exo-(dimethylamino)isoborneol - Origin of the distinct differences in solution-phase behavior and crystal structures , 1996 .

[12]  D. Blackmond,et al.  Origins of asymmetric amplification in autocatalytic alkylzinc additions. , 2001, Journal of the American Chemical Society.

[13]  D. Singleton,et al.  A few molecules can control the enantiomeric outcome. Evidence supporting absolute asymmetric synthesis using the Soai asymmetric autocatalysis. , 2003, Organic letters.

[14]  D. Kondepudi,et al.  A new perspective on the mechanism of asymmetric amplification , 2005 .

[15]  R. Noyori,et al.  Self and nonself recognition of chiral catalysts: the origin of nonlinear effects in the amino-alcohol catalyzed asymmetric addition of diorganozincs to aldehydes. , 2001, Chemical record.

[16]  Steven H. Strogatz,et al.  Nonlinear Dynamics and Chaos , 2024 .

[17]  D. Blackmond,et al.  Asymmetric autocatalysis and its implications for the origin of homochirality , 2004 .

[18]  G. Balavoine,et al.  The Combination of Spontaneous Resolution and Asymmetric Catalysis: A Model for the Generation of Optical Activity from a Fully Racemic System , 2001 .

[19]  Pedro Cintas,et al.  Absolute Asymmetric Synthesis under Physical Fields: Facts and Fictions. , 1998, Chemical reviews.

[20]  K. Mislow,et al.  Absolute Asymmetric Synthesis: A Commentary , 2003 .

[21]  F. Sagués,et al.  Chiral Sign Induction by Vortices During the Formation of Mesophases in Stirred Solutions , 2001, Science.

[22]  K. Tsukiyama,et al.  Evidence of asymmetric autocatalysis in the enantioselective addition of diisopropylzinc to pyrimidine-5-carbaldehyde using chiral pyrimidyl alkanol , 2001 .

[23]  W. H. Mills.  Some aspects of stereochemistry , 1932 .

[24]  F. Frank,et al.  On spontaneous asymmetric synthesis. , 1953, Biochimica et biophysica acta.

[25]  K. Soai,et al.  One-pot asymmetric autocatalytic reaction with remarkable amplification of enantiomeric excess , 1997 .

[26]  D. Kondepudi,et al.  Chiral autocatalysis, spontaneous symmetry breaking, and stochastic behavior. , 2001, Accounts of chemical research.

[27]  H. Quiney,et al.  Reflections on spontaneous asymmetric synthesis by amplifying autocatalysis. , 2003, Organic & biomolecular chemistry.

[28]  Shu-Kun Lin,et al.  Modern Thermodynamics: From Heat Engines to Dissipative Structures , 1999, Entropy.

[29]  G. Lente.  Homogeneous Chiral Autocatalysis: A Simple, Purely Stochastic Kinetic Model , 2004 .

[30]  D. Kondepudi,et al.  Chiral Symmetry Breaking in Sodium Chlorate Crystallizaton , 1990, Science.