Ketoreductase (KRED)-catalyzed dynamic reductive kineticresolution (DYRKR) of α-substituted-β-keto arylphosphonates was developed as a generic and stereoselective approach to synthesize chiral α-substituted-β-hydroxy arylphosphonates, with moderate-to-excellent isolated yield (up to 96%), good-to-excellent diastereoselectivity (up to >99 : <1 dr), and excellent enantioselectivity (up to >99% ee) being
The highly chemo- and enantioselective hydrogenation of (E)-2-substituted-4-oxo-2-alkenoic acids was established for the first time using the Rh/JosiPhos complex, affording a series of chiral α-substituted-γ-keto acids with excellent results (up to 99% yield and >99% ee) and high efficiency (up to 3000 TON). In addition, the importance of this methodology was further demonstrated by a concise and gram-scale
Dynamic kinetic resolution of various α-amido-β-keto phosphonates via asymmetrichydrogenation proceeded efficiently to give the corresponding β-hydroxy-α-amido phosphonates in high diastereo- and enantioselectivities (up to 99:1 syn/anti, 99.8% ee). The addition of catalytic amounts of CeCl3·7H2O is necessary to achieve both good selectivity and catalytic efficiency under mild reaction conditions
Iridium‐catalyzed asymmetric hydrogenation of β‐ketophosphonates with chiral ferrocenyl P,N,N‐ligands
作者:Yin‐Feng Ma、Chuan‐Jin Hou、De‐Quan Wei、Xinwei He、Ting‐Ting Chu、Xiu‐shuai Chen、Xiang‐Ping Hu
DOI:10.1002/aoc.6283
日期:2021.8
The asymmetrichydrogenation of β-ketophosphonates with chiral Ir/P,N,N-ligands catalyst has been developed. A series of β-ketophosphonates were hydrogenated, and the corresponding β-hydroxyphosphonates were obtained in high yields with good or excellent enantioselectivities under mild condition.
Synthesis of ring-contracted, 25-nor-6,5-spiroketal-modified avermectin derivatives
作者:Peter T. Meinke、Stephen P. O'Connor、Helmut Mrozik、Michael H. Fisher
DOI:10.1016/s0040-4039(00)91896-3
日期:1992.2
A versatile, high yielding strategy for the synthesis of ring-contracted, 25-nor-6,5-spiroketal-modified avermectin analogs (7A - 7N) bearing diverse substituents at C24 is described. In addition, an efficient Pb(OAc)4-mediated oxidative cleavage to produce the key intermediate, aldehyde 3, is presented.