60096-50-6Relevant articles and documents
Diastereo- and enantioselective synthesis of 2,3- and 1,2-disubstituted 4-oxophosphonates via asymmetric Michael addition
Enders, Dieter,Wahl, Heiner,Papadopoulos, Kyriakos
, p. 12961 - 12978 (1997)
Asymmetric Michael addition of lithiated SAMP hydrazones (S)-2 to a variety of alkenylphosphonates (E)-3 followed by oxidative cleavage of the 1,4-adducts 4 afforded 2,3-disubstituted 4-oxophosphonates 5 with good to very good yields (58-80%), low to moderate diastereomeric (de = 6-74%) and excellent enantiomeric excesses (ee = >93%). Pure anti-diastereomers (ee = >93%) of 5 were obtained by separation of the stereoisomers by HPLC. In addition, the lithiated SAMP hydrazone (S)-2a was added to alkenylphosphonates (E)-3, and the lithio phosphonate anions were trapped with alkyl halides or sulfates, yielding 1,2-disubstituted 4-oxophosphonates 8 with moderate to good yields (38-69%), low to good diastereomeric (de = 10-77%) and high enantiomeric excesses (ee = >90%) after oxidative cleavage.
Asymmetric Michael Additions via SAMP-/RAMP-Hydrazones Enantioselective 1,4-Addition of Methyl Ketones to Knoevenagel Acceptors
Enders, Dieter,Demir, Ayhan S.,Rendenbach, Beatrice E. M.
, p. 1731 - 1736 (2007/10/02)
Asymmetric Michael addition of lithiated methyl ketone SAMP-hydrazones (S)-2 to 2-benzylidenemalonates and -dinitriles 3 followed by oxidative cleavage of the 1,4-adducts (SR)-4 by ozonolysis affords 2-substituted 4-oxo diesters and -dinitriles (R)-5 in good overall yields of 50-82percent and high enantiomeric excesses (ee >/= 95percent).
ASYMMETRIC MICHAEL ADDITIONS VIA SAMP-/RAMP-HYDRAZONES ANTI-DIASTEREO- AND ENANTIOSELECTIVE SYNTHESIS OF 3,4-DISUBSTITUTED 5-OXO-ALKANOATES
Enders, Dieter,Papadopoulos, Kyriakos,Rendenbach, Beatrice E.M.,Appel, Rolf,Knoch, Falk
, p. 3491 - 3494 (2007/10/02)
An efficient and highly anti-diastereo-(de=90-100percent) and enantioselective (ee=92-100percent) synthesis of 3,4-disubstituted 5-oxo-alkanoates 3 in good overall chemical yields is described.The procedure involves the asymmetric Michael addition of aldehydes or ketones to enoates via their lithiated SAMP-/RAMP-hydrazones.Both enantiomers are accessible at will.