Cyclic imines, generated in situ from their corresponding N-lithiated amines and a ketone hydride acceptor, undergo reactions with a range of organometallic nucleophiles to generate α-functionalized amines in a single operation. Activation of the transient imines by Lewis acids that are compatible with the presence of lithium alkoxides was found to be crucial to accommodate a broad range of nucleophiles including lithium acetylides, Grignard reagents, and aryllithiums with attenuated reactivities.
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http://dx.doi.org/10.1021/jacs.9b04325 | DOI Listing |
Chem Commun (Camb)
December 2024
Process Research & Development, Merck & Co., Inc., Rahway, New Jersey 07065, USA.
We report a general chemoselective strategy for amide bond formation with poorly nucleophilic amines in the presence of reactive primary alcohols or amines as the competing nucleophiles. The selectivity for less reactive amines over competing alcohols was achieved using TCFH and catalytic Oxyma as a highly reactive, inexpensive, and safe reagent combination. By temporarily masking more reactive amines as imines through the use of electron-deficient aldehydes, the hindered amines could be similarly coupled with high efficiency and selectivity.
View Article and Find Full Text PDFJ Am Soc Mass Spectrom
January 2025
Department of Chemistry, Bagley Hall, Box 351700, University of Washington, Seattle, Washington 98195-1700, United States.
Peptide conjugates furnished with a 2,5-diaryltetrazolecarbonyl tag at the C-terminal lysine, which we call peptide--K, were found to undergo efficient cross-linking of Asp, Glu, Asn, and Gln residues to transient nitrile-imine intermediates produced by photodissociation and collision-induced dissociation (CID) of the tetrazole ring in gas-phase ions. UV photodissociation (UVPD) at 213 nm achieved cross-linking conversion yields of 37 and 61% for DAAAK--K and EAAAK--K, respectively. The yields for NAAAK--K and QAAAK--K were 29 and 57%, respectively.
View Article and Find Full Text PDFMolecules
October 2024
Emanuel Institute of Biochemical Physics of the Russian Academy of Sciences, Kosygin St., 4, Moscow 119334, Russia.
ACS Nano
October 2024
Department of Chemistry, Johannes Gutenberg-Universität Mainz, Duesbergweg 10-14, Mainz D-55128, Germany.
Org Lett
October 2024
College of Chemistry, International Phosphorus Laboratory, Zhengzhou University, Zhengzhou 450001, P. R. China.
An efficient and practical method for the preparation of the phospholene fused β-phosphinolactam skeleton from α-C-bridged biphospholes and nitrones is described. The dissociation of biphospholes generates transient 1-phosphafulvenes, followed by oxidation with nitrones to give the 1-phosphafulvene oxides. The oxidation of 1-phosphafulvene boosts its reactivity toward imine, leading to the isolated products.
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