A versatile titanocene-catalyzed radical allyl transfer reaction on epoxides is reported. Epoxide opening occurs regioselectively at the more hindered side, and variously substituted allyl sulfone may be coupled to this position in an efficient manner, enabling a rapid access to quaternary carbon centers with useful functionalities for further elaboration. Furthermore, the procedure can be expanded to stereoselective variants. This new radical allyl transfer expands the scope of allylation in organic synthesis.
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http://dx.doi.org/10.1021/acs.orglett.3c03181 | DOI Listing |
Macromol Biosci
December 2024
INM - Leibniz Institute for New Materials, 66123, Saarbrücken, Germany.
Photocrosslinkable formulations based on the radical thiol-ene reaction are considered better alternatives than methacrylated counterparts for light-based fabrication processes. This study quantifies differences between thiol-ene and methacrylated crosslinked hydrogels in terms of precursors stability, the control of the crosslinking process, and the resolution of printed features particularized for hyaluronic acid (HA) inks at concentrations relevant for bioprinting. First, the synthesis of HA functionalized with norbornene, allyl ether, or methacrylate groups with the same molecular weight and comparable degrees of functionalization is presented.
View Article and Find Full Text PDFJ Am Chem Soc
December 2024
EaStCHEM, School of Chemistry, University of St Andrews, North Haugh, St. Andrews, KY16 9ST, U.K.
The [1,2]-rearrangement of allylic ammonium ylides is traditionally observed as a competitive minor pathway alongside the thermally allowed [2,3]-sigmatropic rearrangement. Concerted [1,2]-rearrangements are formally forbidden, with these processes believed to proceed through homolytic C-N bond fission of the ylide, followed by radical-radical recombination. The challenges associated with developing a catalytic enantioselective [1,2]-rearrangement of allylic ammonium ylides therefore lie in biasing the reaction pathway to favor the [1,2]-reaction product, alongside controlling a stereoselective radical-radical recombination event.
View Article and Find Full Text PDFACS Omega
December 2024
N. D. Zelinsky Institute of Organic Chemistry of the Russian Academy of Sciences, 47 Leninsky prosp., Moscow 119991, Russian Federation.
The electrochemically induced reaction between alkenes, bearing an allylic hydrogen atom, and -hydroxyphthalimide was investigated. Cross-dehydrogenative C-O coupling with phthalimide--oxyl radical, derived from -hydroxyphthalimide, occurs instead of oxidation of the allylic site, with the formation of a carbonyl group or functionalization of the double C=C bond. The discovered transformation proceeds in an undivided electrochemical cell equipped with a carbon felt anode and a platinum cathode.
View Article and Find Full Text PDFOrg Lett
December 2024
School of Chemistry, Dalian University of Technology, 116024 Dalian, China.
This study presents the indium-mediated three-component radical Reformatsky-type allylation of --butanesulfinyl iminoester with 1,3-butadiene. This novel approach offers a rapid synthesis pathway to valuable homoallylic noncanonical amino acids, demonstrated with over 30 examples showing nice regio- and diastereoselectivity. Mechanism studies revealed that allylindium complexes served as key intermediates, formed through a single-electron reduction of allylic radicals by Indium species.
View Article and Find Full Text PDFInt J Biol Macromol
December 2024
PG and Research Department of Chemistry, Sri Ramakrishna Mission Vidyalaya College of Arts and Science, Coimbatore 641 020, Tamil Nadu, India. Electronic address:
Smart polymer hydrogels with superior dye adsorption (brilliant green) characteristics were synthesized via free-radical polymerization by grafting acrylic acid segments onto allylated chitosan and inducing crosslinking with a trimethylolpropane triacrylate crosslinker. The synthesized adsorbents were characterized for their chemical structure (FT-IR and H NMR), thermal stability (TG/DTG), and morphological features (SEM). The adsorption capacity for brilliant green (934 mg/g) and water uptake (712 g/g) were determined using spectrophotometric and gravimetric methods, respectively.
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