Novel photoresponsive cross-linking oligodeoxyribonucleotides having a caged α-chloroaldehyde
摘要:
We have developed photoresponsive cross-linking oligodeoxyribonucleotides (ODNs) for sequence-selective interstrand covalent bond formation toward target nucleotides. A phosphoramidite derivative of alpha-chloroaldehyde whose carbonyl group was converted to a bis(2-nitrobenzyl)acetal group was prepared for the synthesis of photoresponsive alpha-chloroaldehyde (PCA)-conjugated ODN. The bis(2-nitrobenzyl)acetal group of a PCA-thymidine conjugate was completely removed by UV irradiation at 365 nm (400 mW/cm(2)) for 1 min. Photo-cross-linking studies revealed that PCA-ODN selectively reacted with the target nucleotides having an adenine or a cytosine moiety at the frontal position of the alpha-chloroaldehyde group. (C) 2012 Elsevier Ltd. All rights reserved.
Various primary and secondaryalcohols were smoothly oxidized to the corresponding aldehydes and ketones by using a new oxidizing agent, N-t-butylbenzenesulfinimidoyl chloride (4a), in the coexistence of DBU or zinc oxide. The present oxidation proceeded under mild conditions via five-membered intramolecular proton-transfer of an alkyl arenesulfinimidate intermediate.
The Morita‐Baylis–Hillman (MBH) reaction and [3, 3]‐sigmatropic rearrangement are two paradigms in organic synthesis. We have merged the two types of reactions to achieve [3,3]‐rearrangement of arylsulfoxides with α,β‐unsaturated nitriles. The reaction was achieved by sequentially treating both coupling partners with electrophilic activator (Tf2O) and base, offering an effective approach to prepare
Oxalic Acid-promoted Preparation of Dithioacetals from Carbonyl Compounds or Acetals
作者:Hideyoshi Miyake、Yuichi Nakao、Mitsuru Sasaki
DOI:10.1246/cl.2007.104
日期:2007.1
This letter describes oxalic acid-promoted syntheses of dithioacetals from carbonyl compounds and thiols. Acetals are also converted into dithioacetals by the reaction with thiols under similar con...
Chemoselective reduction of aldehydes in the presence of ketones was achieved usingsodium tris(hexafluoroisopropoxy)borohydride which can be stored as a THF solution.
Investigation of the origin and synthetic application of the pseudodilution effect for Pd-catalyzed macrocyclisations in concentrated solutions with immobilized catalysts
作者:Elisabeth Brehm、Rolf Breinbauer
DOI:10.1039/c3ob41020j
日期:——
Immobilized Pd-complexes allowed macrocyclisations via the Tsuji-Trost-reaction in concentrated solutions. Systematic studies suggest that the origin of this pseudodilution effect is neither film diffusion nor gel diffusion, but the reduction in conformational freedom of intermediates and intramolecular prenucleophile activation. In contrast a pseudodilution effect could not be observed for Sonogashira-