96-32-2Relevant articles and documents
Enantioselective Allenoate-Claisen Rearrangement Using Chiral Phosphate Catalysts
Ellwart, Mario,Gensch, Tobias,Han, Seo-Jung,Lin, Hsin-Hui,Miró, Javier,Sigman, Matthew S.,Toste, F. Dean
supporting information, p. 6390 - 6399 (2020/04/27)
Herein we report the first highly enantioselective allenoate-Claisen rearrangement using doubly axially chiral phosphate sodium salts as catalysts. This synthetic method provides access to β-amino acid derivatives with vicinal stereocenters in up to 95percent ee. We also investigated the mechanism of enantioinduction by transition state (TS) computations with DFT as well as statistical modeling of the relationship between selectivity and the molecular features of both the catalyst and substrate. The mutual interactions of charge-separated regions in both the zwitterionic intermediate generated by reaction of an amine to the allenoate and the Na+-salt of the chiral phosphate leads to an orientation of the TS in the catalytic pocket that maximizes favorable noncovalent interactions. Crucial arene-arene interactions at the periphery of the catalyst lead to a differentiation of the TS diastereomers. These interactions were interrogated using DFT calculations and validated through statistical modeling of parameters describing noncovalent interactions.
Photoinduced Intermolecular [4+2] Cycloaddition Reaction for Construction of Benzobicyclo[2.2.2]octane Skeletons
Liu, Qiang,Wang, Junlei,Li, Dazhi,Yang, Chao,Xia, Wujiong
, p. 1389 - 1402 (2017/02/10)
A novel and efficient method for the synthesis of highly substituted benzobicyclo[2.2.2]octane skeletons has been explored. Under UV-light irradiation, o-divinylbenzenes underwent a pericyclic reaction to form the cyclic o-quinodimethane intermediates which were subsequently reacted with olefins through [4+2] addition to construct the benzobicyclo[2.2.2]octane skeletons in mild conditions. Gram scale reactions demonstrated the synthetic potential application of this protocol.
Peptide ligation assisted by an auxiliary attached to amidyl nitrogen
Li, Juan,Cui, Hong-Kui,Liu, Lei
scheme or table, p. 1793 - 1796 (2010/06/13)
New thiol-containing auxiliaries were developed for peptide ligation. They were placed at the amidyl N-atom in the second amino acid residue of a peptide fragment. With the new auxiliaries, peptide ligation could be conducted at non-Cys and non-Gly sites. Compared to other recently developed auxiliaries, an important feature of the present design was that the new auxiliaries were generally applicable and readily removable.
