- Heterodiene cycloadditoins of C2 symmetric 4,5-disubstituted ketene acetals: the nett asymmetric conjugate addition of recyclable acetic ester enolate equivalents to an activated enone
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Heterodiene cycloadditions of 3-formylchromone 2 to a series of ketene acetals 1 derived from C2 symmetric 1,2-diarylethane-1,2-diols are diastereoselective.From (S,S)-1,2-di(o-tolyl)ethane-1,2-diol 6c the major cycloadduct 3c was isolated by crystallization and transformed by acid-catalysed methanolysis into (S)-methyl 4-oxo-3,4-dihydro-2H-1-benzopyran-2-ylacetate 5, together with the original 1,2-diol 6c which could be recycled.The structures of two cyclic carbonates 22a and 22c were determined by X-ray diffraction and used as models in seeking a mechanistic rationale for the stereoselective cycloadditions of the analogous ketene acetals 1a and 1c.
- Wallace, Timothy W.,Wardell, Ian,Li, Ke-Dong,Leeming, Peter,Redhouse, Alan D.,Challand, S. Richard
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p. 2293 - 2308
(2007/10/02)
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- Nett Asymmetric Conjugate Addition of a Recyclable Acetic Ester Enolate Equivalent
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Heterodiene cycloadditions of 3-formyl chromone to ketene acetals derived from C2-symmetric 1,2-diarylethane-1,2-diols are diastereoselective; methanolysis of the cycloadducts derived from (S,S)-hydrobenzoin releases optically enriched methyl 3,4-dihydro-4-oxo-2H-1-benzopyran-2-ylacetate and the optically pure 1,2-diol.
- Wallace, Timothy W.,Wardell, Ian,Li, Ke-Dong,Challand, S. Richard
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p. 1707 - 1708
(2007/10/02)
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