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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Preparation
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9a </A>
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pressure and the residue purified by flash silica chromatography
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20 +18.7
(c 1.25, CHCl3 ) which was
fully characterised.
9b </A>
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approx. 3 M anhyd. methanolic HCl (20 cm3 ) and
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and 13 C NMR spectra.
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