Communication
Organic & Biomolecular Chemistry
base/Pd catalysis. The products are obtained in high yield and
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enantioselectivity using
a range of structurally different
nucleophiles and electrophiles and could be modified and ela-
borated without loss in optical purity. The preparation of
bicycle 50 is noteworthy as it demonstrates straightforward
access to enantioenriched bicyclic pyrroles and validates the
potential suitability of this method to the synthesis of relevant
alkaloid natural products. Finally, the enantioselective
functionalization of tolmetin-Pfp ester 52 extends our method
to more complex pyrrole nucleophiles.
Conflicts of interest
9 (a) D. G. Stark, P. Williamson, E. R. Gayner, S. F. Musolino,
R. W. F. Kerr, J. E. Taylor, A. M. Z. Slawin,
T. J. C. O’Riordan, S. A. Macgregor and A. D. Smith, Org.
Biomol. Chem., 2016, 14, 8957–8965; (b) S. Zhang,
J. E. Taylor, A. M. Z. Slawin and A. D. Smith, Org. Lett.,
2018, 20, 5482–5485.
There are no conflicts to declare.
Acknowledgements
10 (a) P. Liu, X. Yang, V. B. Birman and K. N. Houk, Org. Lett.,
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For a comprehensive discussion of isothioureas as enantio-
selective Lewis base catalysts, see: (e) J. Merad, J.-M. Pons,
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We gratefully acknowledge Indiana University and the NIH
(R01GM121573) for generous financial support. We thank
Dr Maren Pink and Dr Chun-Hsing Chen (IU) for X-ray crystal-
lography. This project was partially supported by the IU Vice
Provost for Research through the Research Equipment Fund.
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Org. Biomol. Chem.
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