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New Auxiliaries for Copper‐Catalyzed Asymmetric Michael Reactions: Generation of Quaternary Stereocenters at Room Temperature
Author(s) -
Christoffers Jens,
Mann Alexander
Publication year - 2001
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/1521-3765(20010302)7:5<1014::aid-chem1014>3.0.co;2-x
Subject(s) - stereocenter , michael reaction , copper , catalysis , chemistry , valine , yield (engineering) , ketone , enantiomeric excess , organic chemistry , methyl vinyl ketone , oxygen , medicinal chemistry , enantioselective synthesis , materials science , amino acid , metallurgy , biochemistry
Dialkyl amides of l‐ valine, l‐ isoleucine, and L ‐ tert ‐leucine ( 2 ) are excellent chiral auxiliaries for the construction of quaternary stereocenters at ambient temperature. Enaminoesters 3 , prepared from these auxiliaries 2 and Michael donors 1 , undergo a copper‐catalyzed asymmetric Michael reaction with methyl vinyl ketone (MVK, 4 ) to afford products 5 in 70–90 % yield and 90–99 % ee (enantiomeric excess). The exclusion of moisture or oxygen is not necessary. The auxiliaries 2 are readily available by standard procedures. After workup they can be recovered almost quantitatively.