Discovery of an Orally Active Series of Isoxazoline Glycoprotein IIb/IIIa Antagonists
作者:Chu-Biao Xue、John Wityak、Thais M. Sielecki、Donald J. Pinto、Douglas G. Batt、Gary A. Cain、Michael Sworin、Arlene L. Rockwell、John J. Roderick、Shuaige Wang、Michael J. Orwat、William E. Frietze、Lori L. Bostrom、Jie Liu、C. Anne Higley、F. Wayne Rankin、A. Ewa Tobin、George Emmett、George K. Lalka、Jean Y. Sze、Susan V. Di Meo、Shaker A. Mousa、Martin J. Thoolen、Adrienne L. Racanelli、Elizabeth A. Hausner、Thomas M. Reilly、William F. DeGrado、Ruth R. Wexler、Richard E. Olson
DOI:10.1021/jm960799i
日期:1997.6.1
Using isoxazoline XR299 (1a) as a starting point for the design of highly potent, long-duration GPIIb/IIIaantagonists, the effect of placing lipophilic substituents at positions alpha and beta to the carboxylate moiety was evaluated. Of the compounds studied, it was found that the n-butyl carbamate 24u exhibited superior potency and duration of ex vivo antiplatelet effects in dogs. Replacement of
Lipase-Involved Strategy to the Enantiomers of 4-Benzyl-β-Lactam as a Key Intermediate in the Preparation of β-Phenylalanine Derivatives
作者:Xiang-Guo Li、Liisa T. Kanerva
DOI:10.1002/adsc.200505253
日期:2006.1
A simple chemoenzymatic method for the preparation of the enantiomers of 4-benzyl-β-lactam (4-benzylazetidin-2-one) from allylbenzene has been described. The enantiomers of this keyintermediate have been used to produce the corresponding enantiomers of β-phenylalanine and N-Boc-protected β-phenylalanine amide through the simple cleavage of the lactam ring by acid-catalyzed hydrolysis and by ammonolysis
Practical and simple catalyticenantioselectivehydrogenation reactions to synthesize N-unprotected β-amino esters have been developed: (1) asymmetrichydrogenation of N-unprotected β-enamine ester and (2) asymmetric direct reductiveamination of β-keto esters using ammonium salts. A Ru–DM-SEGPHOS complex was used as the catalyst in both cases and gave high enantioselectivity, high reactivity, and
General Route to 2,4,5-Trisubstituted Piperidines from Enantiopure β-Amino Esters. Total Synthesis of Pseudodistomin B Triacetate and Pseudodistomin F
作者:Dawei Ma、Haiying Sun
DOI:10.1021/jo000447q
日期:2000.9.1
The Michael addition reaction of enantiopure beta-amino esters with methyl acrylate followed by Dieckmann condensation and enol silylation affords the enol ethers 6, which are hydrogenated with catalysis by Raney-Ni at 80 atm and 80 degrees C to provide 2,4, 5-trisubstituted piperidines with high diastereoselectivity. In this case Ni-H attacks the C-C double bond from the direction of the 2-alkyl group
Highly Efficient Synthesis of β-Amino Acid Derivatives via Asymmetric Hydrogenation of Unprotected Enamines
作者:Yi Hsiao、Nelo R. Rivera、Thorsten Rosner、Shane W. Krska、Eugenia Njolito、Fang Wang、Yongkui Sun、Joseph D. Armstrong、Edward J. J. Grabowski、Richard D. Tillyer、Felix Spindler、Christophe Malan
DOI:10.1021/ja047901i
日期:2004.8.1
A direct asymmetrichydrogenation of unprotected enamino esters and amides is described. Catalyzed by Rh complexes with Josiphos-type chiral ligands, this method gives beta-amino esters and amides in high yield and high ee (93-97% ee). No acyl protection/deprotection is required.
描述了未保护的烯氨基酯和酰胺的直接不对称氢化。该方法由具有 Josiphos 型手性配体的 Rh 络合物催化,以高产率和高 ee (93-97% ee) 得到 β-氨基酯和酰胺。不需要酰基保护/脱保护。