220486-43-1Relevant articles and documents
Catalytic Enantioselective Nazarov Cyclization
Jolit, Anais,Dickinson, Cody F.,Kitamura, Kei,Walleser, Patrick M.,Yap, Glenn P. A.,Tius, Marcus A.
, p. 6067 - 6076 (2017/11/14)
A detailed account of an asymmetric Nazarov cyclization that leads to α-hydroxycyclopentenones bearing either vicinal, all-carbon quaternary centers, or vicinal quaternary and tertiary centers is given. The all-aliphatic examples represent the greatest challenge, as the dienone starting materials are not activated toward cyclization by an aryl group. The rational design and optimization of the substrates in parallel with optimization of the chiral Br?nsted acid catalyst is also described, as well as a series of diastereoselective transformations of a fully substituted cyclopentenone product.
Diastereomeric resolution of rac -1,1′-bi-2-naphthol boronic acid with a chiral boron ligand and its application to simultaneous synthesis of (R)- and (S)-3,3′-disubstituted 1,1′-bi-2-naphthol derivatives
Lee, Chun-Young,Cheon, Cheol-Hong
, p. 7086 - 7092 (2013/08/23)
A new concept of diastereomeric resolution has been developed where a boronic acid functionality was employed as (1) a diastereomeric resolving group with a chiral boron ligand and (2) a masked functional group for further transformation thereafter. This new diastereomeric resolution method was successfully applied to the preparation of both (R)- and (S)-3,3′- disubstituted 1,1′-bi-2-naphthol (BINOL) derivatives in a step-ecomonical manner. Racemic BINOL boronic acid reacted with a commercially available pinene-derived iminodiacetic acid as a chiral boron ligand to generate the two diastereomers in quantitative yields over a gram-scale quantity. After the removal of the chiral boron ligand from the diastereomers under mild conditions, the subsequent Suzuki coupling reaction of the resulting chiral BINOL boronic acids with aryl halides provided a series of both (R)- and (S)-BINOL derivatives in good yields. Further, both resulting diastereomers could be directly applied to the Suzuki coupling reaction without the removal of the chiral ligand.
Copper(I)-catalyzed asymmetric desymmetrization: Synthesis of five-membered-ring compounds containing all-carbon quaternary stereocenters
Aikawa, Kohsuke,Okamoto, Tatsuya,Mikami, Koichi
supporting information; experimental part, p. 10329 - 10332 (2012/07/30)
A highly stereoselective catalytic alkylation sequence for the synthesis of highly functionalized and versatile five-membered-ring compounds bearing all-carbon quaternary stereocenters was developed. Enantioselective desymmetrization of achiral cyclopentene-1,3-diones was thus executed by chiral Cu-phosphoramidite catalysts. A variety of complicated cyclopentane derivatives can be synthesized with excellent stereoselectivities using a low catalyst loading in a one-pot operation.