Ring-Strain-Enabled Catalytic Asymmetric Umpolung C–O Bond-Forming Reactions of 1,2-Oxazetidines for the Synthesis of Functionalized Chiral Ethers
作者:Binyu Wu、Jinggang Yang、Min Gao、Lin Hu
DOI:10.1021/acs.orglett.0c01916
日期:2020.7.17
An unprecedented catalyticasymmetric umpolung C–O bond-forming reaction of N-nosyl 1,2-oxazetidines with β-keto esters has been achieved in the presence of a chiral phase-transfer catalyst, allowing access to a range of highly functionalized chiral ethers bearing quaternary and no adjacent stereogenic centers with high yields, excellent enantioselectivities, and diastereoselectivities (up to 97% ee
Geometrically restricted 2-indolinone derivatives as modulators of protein kinase activity
申请人:Sugen, Inc.
公开号:US06525072B1
公开(公告)日:2003-02-25
The present invention relates to novel geometrically restricted 2-indolinones and physiologically acceptable salts thereof which modulate the activity of protein kinases and therefore are expected to be useful in the prevention and treatment of protein kinase related cellular disorders such as cancer.
The role of internal twisting in the photophysics of stilbazolium dyes
作者:Martin Sczepan、Wolfgang Rettig、A. I. Tolmachev、V. V. Kurdyukov
DOI:10.1039/b102779b
日期:——
The synthesis of selectively bridged stilbazolium dyes related to DASPMI is described. The comparison of steady-state and time-resolved fluorescence studies as a function of temperature allows one to develop a kinetic model on the basis of which the high photostability and absence of photoisomerization for these dyes can be understood. There are two possible photochemical deactivation channels: non-radiative decay through single-bond twisting which does not lead to a distinguishable photoisomer and through double bond twisting leading to trans–cis photoisomerization. The latter process is more than one order of magnitude slower than single-bond
twisting for these compounds and is only observed in the compound where both single bonds are bridged. Lifetime maxima observed at low temperature indicate a further early structural relaxation not connected with bond twisting but with bond length changes.
analogues that form a hydrogen‐bond network in water to improve the two‐photon efficiency. Our design results in two‐photon chalcone (TPC) dyes with 0.80 quantum yield and large two‐photon action cross section (210 GM) in water. This strategy to form hydrogen bonds can be generalized to design two‐photon materials with anti‐solvatochromic fluorescence. To demonstrate the improved in vivo imaging, we designed
H661. Their design is based on indanone (or tetralone) systems leading to trichostatin A (TSA) analogs with limited conformational mobility. Molecular modelization at the AM1 level revealed that the conformations of indane-based analogs and TSA bound to HDAC like protein are similar. The synthesis of these new analogs was achieved by alkylation of an appropriate indanone (or tetralone) to introduce the