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Vinylogous α-Ketol Rearrangement
E. Zhang, C.-A. Fan, Y.-Q. Tu*, F.-M. Zhang, Y.-L. Song
Lanzhou University, P. R. Of China
20 November 2009 (online)
A novel organocatalytic enantioselective vinylogous α-ketol rearrangement via a semipinacol-type 1,2-carbon migration is reported by the authors. With a primary amine catalyst combined with N-Boc-l-phenylglycine (NBLP) as co-catalyst, a series of spirocyclic diketones containing an all-carbon quaternary stereocenter was obtained in good yields and high enantioselectivities (er up to 98.5:1.5). The acid additives showed a significant effect on the stereochemical outcome, and a match-mismatch effect was also observed when using NBLP and NBDP.