Beilstein J. Org. Chem. 2012, 8, 1825–1830.
10.Lee, W.-S.; Ueno, A. Macromol. Rapid Commun. 2001, 22, 448–450.
Conclusion
In summary, we developed a new approach to the design and
synthesis of the novel, photoswitchable guanidine 2. After
detailed investigation of its photochromic properties and
demonstrating its reversible, light-induced switchability, we
started to investigate the reasons for its inactivity in the ROP of
lactide. Our efforts are now directed toward the improvement of
the design of the catalyst by exchanging one aromatic residue
with an alkyl substituent to improve the basicity of guanidine,
as well as by introducing sterically crowded substituents or ring
constraints in order to direct the position of the relevant lone
pair of guanidine as well as the NH-function.
11.Würthner, F.; Rebek, J., Jr. Angew. Chem., Int. Ed. Engl. 1995, 34,
12.Würthner, F.; Rebek, J. J. Chem. Soc., Perkin Trans. 2 1995,
13.Cacciapaglia, R.; Di Stefano, S.; Mandolini, L. J. Am. Chem. Soc.
14.Sun, X.; Gao, J. P.; Wang, Z. Y. J. Am. Chem. Soc. 2008, 130,
15.Dechy-Cabaret, O.; Martin-Vaca, B.; Bourissou, D. Chem. Rev. 2004,
16.Pratt, R. C.; Lohmeijer, B. G. G.; Long, D. A.; Waymouth, R. M.;
Hedrick, J. L. J. Am. Chem. Soc. 2006, 128, 4556–4557.
17.Chuma, A.; Horn, H. W.; Swope, W. C.; Pratt, R. C.; Zhang, L.;
Lohmeijer, B. G. G.; Wade, C. G.; Waymouth, R. M.; Hedrick, J. L.;
Rice, J. E. J. Am. Chem. Soc. 2008, 130, 6749–6754.
Supporting Information
The crystal structure has been deposited at the Cambridge
Crystallographic Data Centre and allocated the deposition
number CCDC 891016.
18.Zhang, L.; Pratt, R. C.; Nederberg, F.; Horn, H. W.; Rice, J. E.;
Waymouth, R. M.; Wade, C. G.; Hedrick, J. L. Macromolecules 2010,
Supporting Information File 1
Experimental details and spectra.
19.Priewisch, B.; Rück-Braun, K. J. Org. Chem. 2005, 70, 2350–2352.
License and Terms
Acknowledgements
This is an Open Access article under the terms of the
Creative Commons Attribution License
We thank Stefan Mebs (HU Berlin) for carrying out the single-
crystal X-ray analysis. Generous support by the German
Research Foundation (DFG via SPP 1178) and the European
Science Foundation (ESF via P2M) is gratefully acknowledged.
We thank BASF AG, Bayer Industry Service, and Sasol
Germany for donations of chemicals.
permits unrestricted use, distribution, and reproduction in
any medium, provided the original work is properly cited.
The license is subject to the Beilstein Journal of Organic
Chemistry terms and conditions:
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