1138326-05-2Relevant articles and documents
Development of Chiral Spiro P-N-S Ligands for Iridium-Catalyzed Asymmetric Hydrogenation of β-Alkyl-β-Ketoesters
Bao, Deng-Hui,Wu, Hui-Ling,Liu, Chao-Lun,Xie, Jian-Hua,Zhou, Qi-Lin
supporting information, p. 8791 - 8794 (2015/11/27)
The chiral tridentate spiro P-N-S ligands (SpiroSAP) were developed, and their iridium complexes were prepared. Introduction of a 1,3-dithiane moiety into the ligand resulted in a highly efficient chiral iridium catalyst for asymmetric hydrogenation of β-alkyl-β-ketoesters, producing chiral β-alkyl-β-hydroxyesters with excellent enantioselectivities (95-99.9 % ee) and turnover numbers of up to 355 000. Bulkyness is the key: New chiral tridentate spiro P-N-S ligands (SpiroSAP) bearing a conformationally constrained 1,3-dithiane moiety were developed. Their iridium catalysts showed excellent enantioselectivities and activity (TON up to 355 000) for asymmetric hydrogenation of β-alkyl-β-ketoesters.
Highly efficient asymmetric transfer hydrogenation of ketones in emulsions
Wang, Weiwei,Li, Zhiming,Mu, Wenbo,Su, Ling,Wang, Quanrui
experimental part, p. 480 - 483 (2010/12/19)
Ru-TsDPEN (TsDPEN = N-(p-tolylsulfonyl)-1,2-diphenylethylenediamine) catalyzed asymmetric transfer hydrogenation of ketones in emulsions is reported for the first time. The new protocol provides markedly enhanced activity and enantioselectivities (up to 99% ee) as compared with results when performed either in an aqueous medium or in common organic solvents.
First generation process for the preparation of the DPP-IV inhibitor sitagliptin
Hansen, Karl B.,Balsells, Jaume,Dreher, Spencer,Hsiao, Yi,Kubryk, Michele,Palucki, Michael,Rivera, Nelo,Steinhuebel, Dietrich,Armstrong III, Joseph D.,Askin, David,Grabowski, Edward J. J.
, p. 634 - 639 (2012/12/25)
A new synthesis of sitagliptin (MK-0431), a DPP-IV inhibitor and potential new treatment for type II diabetes, suitable for the preparation of multi-kilogram quantities is presented. The triazolopyrazine fragment of sitagliptin was prepared in 26% yield over four chemical steps using a synthetic strategy similar to the medicinal chemistry synthesis. Key process developments were made in the first step of this sequence, the addition of hydrazine to chloropyrazine, to ensure its safe operation on a large scale. The beta-amino acid fragment of sitagliptin was prepared by asymmetric reduction of the corresponding beta-ketoester followed by a two-step elaboration to an N-benzyloxy beta-lactam. Hydrolysis of the lactam followed by direct coupling to the triazolopiperazine afforded sitagliptin after cleavage of the N-benzyloxy group and salt formation. The overall yield was 52% over eight steps.
