131651-38-2Relevant articles and documents
Lewis Base-Catalyzed Enantioselective Conjugate Reduction of β,β-Disubstituted α,β-Unsaturated Ketones with Trichlorosilane: E/ Z-Isomerization, Regioselectivity, and Synthetic Applications
Sugiura, Masaharu,Ashikari, Yasuhiko,Takahashi, Yuka,Yamaguchi, Koki,Kotani, Shunsuke,Nakajima, Makoto
, p. 11458 - 11473 (2019/10/11)
The chiral bisphosphine dioxide-catalyzed asymmetric conjugate reduction of acyclic β,β-disubstituted α,β-unsaturated ketones with trichlorosilane affords saturated ketones having a stereogenic carbon center at the carbonyl β-position with high enantioselectivities. Because the E/Z-isomerizations of enone substrates occur concomitantly, reduction products with the same absolute configurations are obtained from either (E)- or (Z)-enones. Conjugate reduction is accelerated in the presence of an electron-rich aryl group at the β-position of the enone owing to its carbocation-stabilizing ability. Computational studies were also conducted in order to elucidate the origin of the observed enantioselectivity. The regio- and enantioselective reductions of dienones were realized and applied to the syntheses of ar-turmerone, turmeronol A, mutisianthol, and jungianol, which are optically active sesquiterpenes.
Lipase-mediated resolution of substituted 2-aryl-propanols: Application to the enantioselective synthesis of phenolic sesquiterpenes
Serra, Stefano
, p. 619 - 628 (2011/07/08)
A comprehensive study of the lipase-mediated resolution of substituted 2-aryl-propanols is reported. The latter alcohols were submitted to the irreversible acetylation catalyzed either by PPL, CRL, or lipase PS. The enantioselectivity of these transformations was dependent on the type of lipase used. The type of substituents and particularly their position on the aromatic ring strongly affected the selectivity of the reaction. The experiments described prove that PPL is the more versatile lipase catalyzing the acetylation with an enantiomeric ratio (E) value that ranges from 1 up to 144, depending on the substrate used. Conversely, the same transformations were catalyzed by CRL and lipase PS with an enantiomeric ratio value, which is always less than 5. The remarkable behavior of PPL was exploited in the large scale resolution of some substituted 2-aryl-propanols whose enantiomeric forms are relevant building blocks in the enantioselective synthesis of phenolic sesquiterpenes. By these means, the synthesis of (S)-turmeronol B and the formal syntheses of (R)-curcumene, (R)-curcuphenol, (R)-xanthorrhizol, and (R)-curcuhydroquinone were accomplished.
Use of 1,1'-binaphthalene-8,8'-diol as a chiral auxiliary for asymmetric Michael addition. Application to the syntheses of turmeronol A and B
Tanaka, Kiyoshi,Nuruzzaman, Mohammad,Yoshida, Masato,Asakawa, Naoyuki,Yang, Xiao-Shen,Tsubaki, Kazunori,Fuji, Kaoru
, p. 1053 - 1055 (2007/10/03)
Highly diastereoselective Michael addition of lithium diorganocuprates to the half-ester of 1,1'-binaphthalene-8,8'-diol gave β-substituted esters with high enantiomeric excess after methanolysis. The optically active phenolic sesquiterpenes turmeronol A (1) and B (2) have been synthesized using this reaction as a key step.
