851968-99-5Relevant academic research and scientific papers
Enantioselective α-benzylation of aldehydes via photoredox organocatalysis
Shih, Hui-Wen,Vander Wal, Mark N.,Grange, Rebecca L.,MacMillan, David W. C.
supporting information; experimental part, p. 13600 - 13603 (2010/11/18)
The first enantioselective aldehyde α-benzylation using electron-deficient aryl and heteroaryl substrates has been accomplished. The productive merger of a chiral imidazolidinone organocatalyst and a commercially available iridium photoredox catalyst in the presence of household fluorescent light directly affords the desired homobenzylic stereogenicity in good to excellent yield and enantioselectivity. The utility of this methodology has been demonstrated via rapid access to an enantioenriched drug target for angiogenesis suppression.
Chiral linker 5: scope and limitations of arylsubstituted m-hydrobenzoins as solid supported open chain chiral auxiliaries for diastereoselective syntheses
Broeker, Joachim,Knollmueller, Max,Gaertner, Peter
experimental part, p. 273 - 287 (2009/09/05)
The applicability of five aryl substituted m-hydrobenzoin ethers already tested in the L-Selectride mediated stereoselective reduction of phenylglyoxylates as open chain chiral auxiliaries was further investigated via the α-alkylation of propionates, the addition of n-BuZnCl to phenylglyoxylates and the Diels-Alder reaction of acrylates with cyclopentadiene as model reactions. As up to 90% de could be achieved in the solution phase, two optimized auxiliary structures were immobilized on commercially available Wang-resin and applied as a reusable solid supported chiral auxiliaries in the same type of reactions.
Design and synthesis of a new polymer-supported Evans-type oxazolidinone: An efficient chiral auxiliary in the solid-ph ase asymmetric alkylation reactions
Kotake, Tomoya,Hayashi, Yoshio,Rajesh,Mukai, Yoshie,Takiguchi, Yuka,Kimura, Tooru,Kiso, Yoshiaki
, p. 3819 - 3833 (2007/10/03)
Wang resin-supported Evans' chiral auxiliary (23) was designed based on a novel polymer-anchoring strategy, which utilizes the 5-position of the oxazolidinone ring, and its new synthetic route applicable to multi-gram preparation in just a day was developed. Solid-phase Evans' asymmetric alkylation on 23-derived N-acylimide resin and following lithium hydroperoxide-mediated chemoselective hydrolysis afforded the corresponding α-branched carboxylic acids in desired high stereoselectivities (up to 97% ee) and moderate to good overall yield (up to 70%, for 3 steps), which were comparable to those of the conventional solution-phase methods. Furthermore, recovery and recycling of the polymer-supported chiral auxiliary were successfully achieved without decreasing the stereoselectivity of the product. Therefore, this is the first successful example that the solid-phase Evans' asymmetric enolate-alkylation was efficiently performed on the solid-support, and it is concluded that the connection to the solid-support via the 5-position of the oxazolidinone ring is an ideal strategy in the solid-phase Evans' chiral auxiliary.
Highly rigid diphosphane ligands with a large dihedral angle based on a chiral spirobifluorene backbone
Cheng, Xu,Zhang, Qi,Xie, Jian-Hua,Wang, Li-Xin,Zhou, Qi-Lin
, p. 1118 - 1121 (2007/10/03)
High and wide: The high rigidity and large dihedral angle of chiral, spirobifluorene-based diphosphane ligands lead to excellent reactivity and enantioselectivity in the ruthenium-catalyzed asymmetric hydrogenation of α,β-unsaturated carboxylic acids (see scheme).
