Stereodivergent Approach to β-Hydroxy α-Amino Acids from C2-Symmetrical Alk-2-yne-1,4-diols
摘要:
[GRAPHICS]A new stereodivergent route to erythro- and threo-beta-substituted serines from a common G-symmetrical alk-2-yne-1,4-diol is described. Stereocontrol in such an acyclic system is achieved by taking advantage of symmetry. Stereoselective alkyne reduction to either (Z)- or (E)-olefin allows selection of the stereochemistry of cc-carbon in the final amino acid by using a Pd(0)-catalyzed process. This strategy has been applied to the synthesis of (2S,3S)-3-hydroxyleucine.
A novel, stereodivergent route to paraconic acids from C 2-symmetric trans- and cis-alk-2-ene-1,4-diols through Ireland-Claisen and/or Johnson orthoester rearrangements is disclosed. This strategy has been applied to the synthesis of (-)-methylenolactocin and (-)-phaseolinic acid from a single chiral diol.
[GRAPHICS]A new stereodivergent route to erythro- and threo-beta-substituted serines from a common G-symmetrical alk-2-yne-1,4-diol is described. Stereocontrol in such an acyclic system is achieved by taking advantage of symmetry. Stereoselective alkyne reduction to either (Z)- or (E)-olefin allows selection of the stereochemistry of cc-carbon in the final amino acid by using a Pd(0)-catalyzed process. This strategy has been applied to the synthesis of (2S,3S)-3-hydroxyleucine.
[3,3]-Sigmatropic Rearrangements in the Enantioselective Synthesis of (-)-Methylenolactocin
A Pd(II)-catalyzed [3,3]-sigmatropicrearrangement is used to transfer chirality from an enantio-enriched alk-3-ene-1,2-diol to a C 2 -symmetrical alk-2-ene-1,4-diol which, in turn, can be converted into a precursor of (-)-methylenolactocin through an additional [3,3]-sigmatropicrearrangement (either Johnson orthoester or Ireland-Claisen rearrangement).