An experimentally simple additive-free Rh(III)-catalysed direct alkynylation of alkenes has been developed. This protocol employs commercially available TIPS-EBX as the alkyne source, giving access to conjugated terminal enynes following a simple silyl-deprotection. This method has also been applied to arenes.
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http://dx.doi.org/10.1039/c4cc01141d | DOI Listing |
J Org Chem
December 2024
Department of Chemical Science and Engineering, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan.
A three-component synthesis of multiply functionalized 5,6-dehydroisoquinuclidines is described. After the formation of an -alkylpyridinium salt, Grignard addition led to the formation of the corresponding 1,2-dihydropyridine bearing an alkyl, alkene, aryl, or alkynyl group. Subsequent Diels-Alder reaction with a dienophile provided functionalized dehydroisoquinuclidines in high yields (up to 93%) with selectivities (73:27 to >99:1).
View Article and Find Full Text PDFAngew Chem Int Ed Engl
October 2024
Key Laboratory of Molecule Synthesis and Function Discovery, Fujian Province University, College of Chemistry at Fuzhou University, Fuzhou, Fujian, 350108, China.
Zweifel reaction is a powerful strategy to construct olefins from alkenyl tetracoordinate borons in organoboron chemistry, however, it usually only involves one functional group migration and then undergoes an elimination process affording alkenes or alkynes exclusively. Herein, we disclose several intriguing interception of alkynyl tetracoordinate borons with sulfur electrophiles. Wherein, the substituted benzothiophenes are accessed by consecutive 1,2-migrations and intramolecular electrophilic substitution, meanwhile, the challenging and elusive five/four-membered boracycles are easily assembled, and an approach to alkenyl sulfides with good stereoselectivity was developed as well.
View Article and Find Full Text PDFChem Sci
September 2024
Department of Organic Chemistry, Indian Institute of Science Bangalore-560012 India https://atbiju.in/.
Strain-release driven annulations with bicyclo[1.1.0]butanes (BCBs) have become an attractive area of research for the synthesis of bioisosteric bicyclohexane derivatives, which play a vital role in drug discovery.
View Article and Find Full Text PDFJ Org Chem
September 2024
Department of Chemistry, Yeungnam University, Gyeongsan, Gyeongbuk 38541, Republic of Korea.
Triplet energy transfer (EnT)-promoted photochemical pathways, arisen by visible light and its photosensitizers, have gained significant attention as a complementary strategy for initiating organic transformations in photochemical reactions that are unlikely to occur through a single electron transfer (SET) process. In the present study, we investigated the triplet EnT-promoted 1,3-dipolar cycloaddition reactions of -(trimethylsilyl)methylphthalimide with electron-deficient alkynyl and alkenyl dipolarophiles. The triplet excited state of -(trimethylsilyl)methylphthalimide, promoted by the triplet EnT from thioxanthone (TXA) photosensitizer, underwent sequential intramolecular SET and carbon-to-oxygen migration of the silyl group to form azomethine ylide.
View Article and Find Full Text PDFACS Catal
August 2024
Institute of Applied Synthetic Chemistry, TU Wien, Getreidemarkt 9/163-AC, Wien A-1060, Austria.
A stereo- and regioselective Mn(I)-catalyzed hydroboration of terminal alkynes with pinacolborane (HBPin) is described. The hydroboration reaction is highly -selective in the case of aryl alkynes and -selective in the case of aliphatic alkynes. The reaction requires no additives or solvents and proceeds with a catalyst loading of 1 mol % at 50-70 °C.
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