solution in cyclohexane, 1.8 mmol), O-alkyl carbamate 24
(345 mg, 1.3 mmol) and Bu3SnCl (0.4 cm3, 1.5 mmol) in Et2O
(9 cm3) gave the crude product. Purification by flash column
chromatography using 40 : 1 petrol–Et2O as eluent gave adduct
(R)-25 (135 mg, 18%, 54 : 46 er by chiral HPLC) as a colourless
oil, [a]D −2.6 (c 1.0 in CHCl3).
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Acknowledgements
We thank the EPSRC for funding (of MJM), the EU for Erasmus
funding (of CG) and The Royal Society of Chemistry for the
award of a J W T Jones Travelling Fellowship (to PO’B) for a
sabbatical stay at the University of Geneva. We are particularly
grateful to Dr Jotham W Coe (Pfizer, Groton USA) for providing
details of the chiral HPLC of N-benzyl cytisine and to Darren
Stead for a sample of racemic N-benzyl cytisine. We also thank
Prof Dieter Hoppe (Wilhelms-Universita¨t Mu¨nster) for exchange
of information.
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1382 | Org. Biomol. Chem., 2006, 4, 1376–1382
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