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BIBTEX RIS

α‘-Hydroxy Enones as Achiral Templates for Lewis Acid-Catalyzed Enantioselective Diels−Alder Reactions

2003; American Chemical Society; Volume: 125; Issue: 46 Linguagem: Inglês

10.1021/ja0368002

ISSN

1943-2984

Autores

Claudio Palomo, Mikel Oiarbide, Jesús M. Garcı́a, Alberto González, Elena Arceo,

Tópico(s)

Advanced Synthetic Organic Chemistry

Resumo

alpha'-Hydroxy enones react with dienes in the presence of (S,S)-[Cu(tBu-box)](OTf)2 or (S,S)-[Cu(tBu-box)](SbF6)2 (2 to 10 mol %) to afford the corresponding Diels-Alder adducts in high yield and selectivity. Isomeric ratios (regioselectivity, endo/exo or cis/trans) of up to >99:1 and ee values of up to >99% are obtained. Significantly, difficult dienes such as isoprene, 2,3-dimethyl butadiene and piperylene behave satisfactorily. Subsequent oxidative cleavage of the ketol in the resulting cycloadducts by treatment with cerium ammonium nitrate (CAN) yields the corresponding enantiopure carboxylic acids. Alternatively, carbonyl addition and subsequent diol cleavage with CAN produces the corresponding ketone adducts.

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