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Synlett 2003(3): 0369-0371
DOI: 10.1055/s-2003-37107
LETTER
© Georg Thieme Verlag Stuttgart · New York

Enantiopure Guanidine Bases for Enantioselective Enone Epoxidations: 2, Cyclic Guanidines

Julie C. McManusa, Thorsten Genskia, John S. Careyb, Richard J. K. Taylor*a
a Department of Chemistry, University of York, Heslington, York YO10 5DD, UK
Fax: +44(1904)434523; e-Mail: rjkt1@york.ac.uk;
b GlaxoSmithKline Pharmaceuticals, Leigh, Tonbridge, Kent TN11 9AN, UK
Further Information

Publication History

Received 20 December 2002
Publication Date:
07 February 2003 (online)

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Abstract

A range of structurally and functionally varied enantiopure cyclic and bicyclic guanidines has been prepared and evaluated in the enantioselective epoxidation of 3-tert-butoxycarbonylamino-4,4-dimethoxycyclohexa-2,5-dien-1-one 1 using tert-butylhydroperoxide. Encouraging enantiomeric excesses were observed (up to 60%). Low enantiomeric excesses were also observed with 2-methylnaphthoquinone and trans-chalcone.

Key words

enantioselective - epoxidation - enones - guanidines - stereoselectivity

    References

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8

All new compounds were fully characterised by 1H NMR, 13C NMR and IR, plus HRMS or elemental analysis.

11

Rapid hydrolysis to DMPU occurred; a one-pot variant was also unsuccessful.

13

Chiral HPLC was carried out using a Chiralcel OJ column (25 cm × 4.6 mm) with hexane-isopropanol (98:2) as eluent at a flow rate of 1 mL/min and detection at 276 nm.