On the economic application of DuPHOS rhodium(I) catalysts: a comparison of COD versus NBD precatalysts
摘要:
The effectiveness of cyclooctadiene and norbornadiene precatalysts of the type [Rh(DuPHOS)(diolefin)]BF4 in catalytic asymmetric hydrogenation of various prochiral olefins has been examined. In some of the systems studied, the NBD complex gave rise to the catalytically active species more rapidly than the corresponding COD complex, as expected. However, as catalyst loadings were reduced to levels more conducive to economic manufacture, the difference between the use of COD and NBD precatalysts became increasingly insignificant. This was conveniently highlighted by the formation of low enantiomeric excess products upon using an equimolar mixture of (S,S) and (R,R) precatalysts, bearing COD and NBD respectively. With other substrates, the system displayed no induction time for either precatalyst and identical reaction profiles were observed. (C) 2001 Elsevier Science Ltd. All rights reserved.
<i>Carica papaya</i>Lipase Catalysed Resolution of β-Amino Esters for the Highly Enantioselective Synthesis of (<i>S</i>)-Dapoxetine
作者:Pengyong You、Jian Qiu、Erzheng Su、Dongzhi Wei
DOI:10.1002/ejoc.201201055
日期:2013.1
CPL-catalysed resolution. The mechanism of the CPL-catalysed enantioselective alcoholoysis of the amino acids is discussed to delineate the substrate requirements for CPL-catalysed resolution. Finally, the reaction was scaled up, and the products were separated and obtained in good yields (≥ 80 %). The (S)-3-amino-3-phenylpropanoic acid obtained was used as a key chiral intermediate in the synthesis
Described herein are compounds that are useful as protein kinase inhibitors having the formula:
wherein Z
1
and Z
2
are each independently nitrogen or CH and Ring A, T
m
R
1
, QR
2
, U
n
R
3
, and Sp are as described in the specification. The compounds are especially useful as inhibitors of ERK2 and for treating diseases in mammals that are alleviated by a protein kinase inhibitor, particularly diseases such as cancer, inflammatory disorders, restenosis, diabetes, and cardiovascular disease.
The invention relates to compounds of formula I
wherein R
1
, R
2
, R
4
, R
a
, R
b
, R
c
, R
e
, A*, W
1
, W
2
and W
3
are as defined in claim
16
, for the treatment of CXCR3 related diseases.
Chiral 1,2,4-triazoles: stereoselective acylation and chlorination
作者:Alan R. Katritzky、Dmytro Fedoseyenko、Myong S. Kim、Peter J. Steel
DOI:10.1016/j.tetasy.2009.12.007
日期:2010.1
Acyl groups are transferred from diverse N- and O-acyl derivatives of chiral 3.5-bis-(1-hydroxyethyl)-[ 1,2,4]-triazole to amino acid esters enantioselectively, with 7% to 68% ee. depending on the temperature conditions and nature of the reagents Thionyl chloride replaced the hydroxyl groups of (S)-1-[4-amino5-((S)- 1-hydroxy-ethyl)-[1,2,4]-triazol-3-yl]-ethanol 3 stereospecifically with inversion, as confirmed by X-ray analysis, which also revealed unusual crystal structures with asymmetric units comprising three molecules of 4-amino-3,5-bis(R-1-chloroethyl)-1,2,4-triazole 5 and four of 3,5-bis((R)-1-chloroethyl)-1H-1,2,4-triazole 6. (c) 2010 Elsevier Ltd All rights reserved
Rational de novo design of NADH mimic for stereoselective reduction based on molecular orbital calculation
The methodology of rational design of NADH mimics in stereoselective reduction of carbonyl and imino groups based on molecular orbital calculation was described. The designed NADH mimics la and Ib were subjected to the reduction of benzoylformate and acetyliminophenylacetate. As expected from the calculations of the transition-states, the reduction with la proceeded with high stereoselectivity in both substrates, while Ib showed much lower chirality transfer. (C) 1997 Elsevier Science Ltd. All rights reserved.