184840-89-9Relevant articles and documents
Synthesis of Highly Functionalized Hydrindanes via Sequential Organocatalytic Michael/Mukaiyama Aldol Addition and Telescoped Hydrozirconation/Cross-Coupling as Key Steps: En Route to the AB System of Clifednamides
Sinast, Moritz,Claasen, Birgit,St?ckl, Yannick,Greulich, Andreas,Zens, Anna,Baro, Angelika,Laschat, Sabine
, p. 7537 - 7551 (2021)
The AB ring systems of the clifednamide family, polycyclic tetramate macrolactames (PoTeMs), were prepared by a new, convergent approach employing an intramolecular Diels-Alder (IMDA) reaction. Key steps comprise an organocatalytic Michael addition (>90% enantiomeric excess (ee)), a Mukaiyama aldol reaction for the convergent installation of a diene moiety, and a telescoped hydrozirconation/cross-coupling grafting an enone. The following IMDA furnished a highly functionalized hydrindane (diastereomeric ratio (dr) = 91:1) with the same configuration as the clifednamide scaffold. Advantages of this route are only one required protecting group, 13% overall yield over 9 steps (reduced from previously 17 steps/1.3% overall), and the potential access to the key intermediates in the clifednamide biosynthesis.
Enantioselective, organocatalytic oxy-Michael addition to γ/δ-hydroxy-α,β-enones: Boronate-amine complexes as chiral hydroxide synthons
De, Run Li,Murugan, Andiappan,Falck
, p. 46 - 48 (2008/09/20)
An organocatalytic, enantioselective oxy-Michael addition to achiral γ- and δ-hydroxy-α,β-enones was developed. The key transformation is an unprecedented, asymmetric conjugate addition triggered by complexation between an in situ generated boronic acid hemiester and a chiral amine catalyst. Functionally, the intermediate amine-boronate complex acts as a chiral hydroxide surrogate or synthon. The resultant chiral β-hydroxy-ketones are obtained in good to excellent yields and high ee following mild oxidative removal of the cyclic boronate. Natural products (R,12Z,15Z)-2-hydroxy-4-oxohenicosa-12,15-dienyl acetate and (+)-(S)-streptenol A were synthesized to demonstrate the utility of this reaction. Copyright
