Optically active stannolanes and trigonal bipyramidal pentacoordinated tin complexes were readily prepared by radical cyclization of N-propargylated chiral aza-Morita-Baylis-Hillman adducts induced by Bu(3)SnH. A translocated radical through the cyclization attacked the Bu(3)Sn group in an S(H)2 manner.
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http://dx.doi.org/10.1039/c2cc31753b | DOI Listing |
J Am Chem Soc
December 2024
Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306, United States.
We present a six-step cascade that converts 1,3-distyrylbenzenes (-stilbenes) into nonsymmetric pyrenes in 40-60% yields. This sequence merges photochemical steps, ,-alkene isomerization, a 6π photochemical electrocyclization (Mallory photocyclization); the new bay region cyclization, with two radical iodine-mediated aromatization steps; and an optional aryl migration. This work illustrates how the inherent challenges of engineering excited state reactivity can be addressed by logical design.
View Article and Find Full Text PDFJ Am Chem Soc
December 2024
N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 47 Leninsky prosp., Moscow 119991, Russian Federation.
The selective reaction of cyclic aminoperoxides with FeCl proceeds through a sequence of O-O and C-C bond cleavages, followed by intramolecular cyclization, yielding functionalized tetrahydrofurans in 44-82% yields. Replacing the peroxyacetal group in the peroxide structure with a peroxyaminal fragment fundamentally alters the reaction pathway. Instead of producing linear functionalized ketones, this modification leads to the formation of hard-to-access substituted tetrahydrofurans.
View Article and Find Full Text PDFJ Org Chem
December 2024
College of Biological, Chemical Sciences and Engineering, Jiaxing University, Jiaxing 314001, Zhejiang, China.
In this work, a switchable synthesis of β-ketosulfone and α-chloroketone through a radical difunctionalization of alkenes is reported. The transformation works well under iron peroxo species/photoredox dual catalysis and an open-flask atmosphere, and the reaction is highlighted with good yields and a broad reaction scope. Mechanism studies show that the reaction is initiated by a formal [4 + 2] cyclization of the sulfonyl radical in a regioselective manner.
View Article and Find Full Text PDFOrg Lett
December 2024
National Engineering Research Center for Carbohydrate Synthesis, Jiangxi Normal University, Nanchang 330022, China.
We have developed a glycosyl radical-based synthesis of -alkyl glycosides through a deoxygenative Giese addition-reduction-cyclization cascade, in which readily available 1-hydroxy carbohydrates serve as precursors for glycosyl radicals and aryl alkenes function as radical acceptors. This reaction not only provides an effective method for accessing a previously underexplored class of functionalized cyclopropanes but also enhances the application of Giese addition in the synthesis of -alkyl glycosides by derivatizing the radical intermediate generated through polar cyclization to yield a cyclopropane.
View Article and Find Full Text PDFJ Org Chem
December 2024
Department of Chemistry, Indian Institute of Technology Delhi, New Delhi 110016, India.
We report a visible-light-assisted tandem oxidative 5--dig cyclization of 1,6-enynes for the synthesis of aminated C-3 aryloylated benzofuran, furopyridine, benzothiophene, and indole derivatives. The nitrogen-centered radical generated in situ from -aminopyridinium salt initiates the consecutive formation of C-N, C-C, and C-O bonds. The methodology exhibits good functional group tolerance and regioselectivity, furnishing products in good to excellent yields at room temperature.
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