Steric Control of Geminal Lewis Pair Behavior: Frustration Induced Dyotropic Rearrangement
Received: 18 March 2014
Accepted after revision: 22 April 2014
06 June 2014 (online)
A series of methylene-linked boron/nitrogen geminal Lewis pairs were synthesized and the impacts of sterical effect on their chemical behavior were systematically investigated. Increasing the steric demand around the boron atom is manifested first by an incremental change in the structure of the resulting dative adducts. Accordingly, in the case of phenyl substituents (Alk2NCH2BPh2), formation of head-to-tail dimers/oligomers was observed, while such an intermolecular association was avoided when o-tolyl moiety was introduced [Alk2NCH2B(o-Tol)2], affording only an intramolecular dative complex. Further increase of sterical hindrance to a point (i.e. using mesityl substituents), however, caused a radical change in the structure; a dyotropic rearrangement occurred. Thus, steric interference induced a rearrangement in the geminal pair to relieve or minimize the frustration strain.
References and Notes
- 1 Welch GC, San Juan RR, Masuda JD, Stephan DW. Science 2006; 314: 1124
- 2a Stephan DW, Erker G. Angew. Chem. Int. Ed. 2010; 49: 46
- 2b Topics in Current Chemistry: Frustrated Lewis Pairs I. Stephan DW, Erker G. Springer; New York: 2013. Vol. 332
- 2c Topics in Current Chemistry: Frustrated Lewis Pairs II. Stephan DW, Erker G. Springer Press; New York: 2013. Vol. 334
- 3a Theuergarten E, Schlüns D, Grunenberg J, Daniliuc CG, Jones PG, Tamm M. Chem. Commun. 2010; 46: 8561
- 3b Chernichenko K, Nieger M, Leskelä M, Repo T. Dalton Trans. 2012; 41: 9029
- 3c Holtrichter-Rößmann T, Rösener C, Hellmann J, Uhl W, Würthwein E.-U, Fröhlich R, Wibbeling B. Organometallics 2012; 31: 3272
- 3d Zheng W, Pi C, Wu H. Organometallics 2012; 31: 4072
- 3e Freitag S, Henning J, Schubert H, Wesemann L. Angew. Chem. Int. Ed. 2013; 52: 5640
- 3f Stute A, Kehr G, Fröhlich R, Erker G. Chem. Commun. 2011; 47: 4288
- 3g Rosorius C, Kehr G, Fröhlich R, Grimme S, Erker G. Organometallics 2011; 30: 4211
- 3h Xu X, Kehr G, Daniliuc CG, Erker G. J. Am. Chem. Soc. 2013; 135: 6465
- 3i Bertini F, Hoffmann F, Appelt C, Uhl W, Ehlers AW, Slootweg JC, Lammertsma K. Organometallics 2013; 32: 6764
- 3j Bertini F, Lyaskovskyy V, Timmer BJ. J, de Kanter FJ. J, Lutz M, Ehlers AW, Slootweg JC, Lammertsma K. J. Am. Chem. Soc. 2012; 134: 201
- 4 Zhao L, Lu G, Huang F, Wang Z.-X. Dalton Trans. 2012; 41: 4674
- 5 Cox PJ, Doidge-Harrison SM. S. V, Howie RA, Nowell IW, Taylor OJ, Wardell JL. J. Chem. Soc., Perkin Trans. 1 1989; 2017
- 6 In the present study, the DFT calculations were carried out using the ωB97X-D functional. The energy values reported in the paper correspond to solution-phase Gibbs free energies that are based on ωB97X-D/6-311++G(3df,3pd) electronic energies and all additional terms (thermal contributions and solvent effects) obtained at the ωB97X-D/6-311G(d,p) level. For further details, see Supporting Information.
- 7 For a review on dyotropic reactions, see: Fernández I, Cossío FP, Sierra MA. Chem. Rev. 2009; 109: 6687
- 8a Davis RL, Leverett CA, Romo D, Tantillo DJ. J. Org. Chem. 2011; 76: 7167
- 8b Leverett CA, Purohit VC, Johnson AG, Davis RL, Tantillo DJ, Romo D. J. Am. Chem. Soc. 2012; 134: 13348
- 8c Fernández I, Bickelhaupt FM, Cossío FP. Chem. Eur. J. 2012; 18: 12395
- 8d Gutierrez O, Tantillo DJ. J. Org. Chem. 2012; 77: 8845
- 9 Short H…H bond distances measured in the equilibrium structure of III are clear indications of the internal strain (see Supporting Information).
- 10 The computed free energy balance cannot be regarded as a very accurate prediction due to the inaccuracy of the present computational approach. The error bar on the relative Gibbs free energies reported in the present work is expected to be about 3–4 kcal/mol.
For recent reviews, see:
For a selection of recent theoretical mechanistic studies of dyotropic rearrangements, see: