65651-53-8Relevant articles and documents
First highly efficient asymmetric synthesis of the Hyrtios erectus diketotriterpenoid
Enders, Dieter,Schuesseler, Thomas
, p. 2280 - 2288 (2007/10/03)
The first highly efficient asymmetric synthesis of the diketotriterpenoid 1, isolated from the Indonesian marine sponge Hyrtios erectus, in good overall yield and employing simple starting materials such as butanone, is described. Both stereogenic centres at the C-6 and C-19 positions of the C2-symmetrical molecule were generated via α-alkylation employing the SAMP/RAMP hydrazone method with high asymmetric inductions (de, ee ≥ 96%). The absolute configuration of the natural material was determined as R,R.
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).