Carbocyclization by Radical Closure onto O-Trityl Oximes: Dramatic Effect of Diphenyl Diselenide
摘要:
O-Trityl oximes of 5- and 6-iodoaldehydes undergo radical cyclization to produce oximes when treated in refluxing tetrahydrofuran (THF) with Bu3SnH, 1,1'-azobis(cyclohexanecarbonitrile), i-Pr2NEt, and diphenyl diselenide (PhSeSePh).
Enantio‐ and Regioselective Palladium(II)‐Catalyzed Dioxygenation of (Aza‐)Alkenols
作者:Sabrina Giofrè、Letizia Molteni、Donatella Nava、Leonardo Lo Presti、Egle Maria Beccalli
DOI:10.1002/anie.202109312
日期:2021.9.27
An oxidative Pd-catalyzed intra-intermolecular dioxygenation of (aza-)alkenols has been reported, with total regioselectivity. To study the stereoselectivity, different chiral ligands as well as different hypervalent-iodine compounds have been compared. In particular, by using a C-6 modified pyridinyl-oxazoline (Pyox) ligand and hypervalent iodine bearing an aromatic ring, an excellent enantio- and
BCl3 as the sole boron source, the boryl group and thiol group are added to the C-C double bonds simultaneously. After hydrolysis, the corresponding ((tetrahydrothiophen-2-yl)methyl)boronic acid, ((tetrahydro-2H-thiopyran-2-yl)methyl)boronic acid, ((2,3-dihydrobenzo[b]thiophen-2-yl)methyl)boronic acid and (thiomorpholin-2-ylmethyl)boronic acid are obtained with good yield. The boronic acids obtained
Enantioselective “clip-cycle” synthesis of di-, tri- and spiro-substituted tetrahydropyrans
作者:Khadra Alomari、N. Sai Pavan Chakravarthy、Bastien Duchadeau、Kristaps Ermanis、Paul A. Clarke
DOI:10.1039/d2ob00023g
日期:——
ω-Unsaturated alcohols were “clipped” via alkene metathesis to a thioester activating group, which was followed by a chiral phosphoric acid catalyzed intramolecular oxa-Michael cyclization to yield tetrahydropyrans and spiro-tetrahydropyrans with excellent enantioselectivity. The mechanism and origin of the enantioselectivity was probed by DFT calculations and kinetic isotope studies, where there was
Tuning the Reactivity of Alkoxyl Radicals from Cyclization to 1,2-Silyl Transfer: Stereoselective Synthesis of β-Substituted Cycloalcohols
作者:Xingyi He、Yunlong Zhao、Zeguo Zhang、Xiao Shen
DOI:10.1021/acs.orglett.2c00428
日期:2022.3.18
Herein, we report a radical strategy for diastereoselective construction of β-substituted cyclopentanols and cyclobutanols. The success of the reaction is attributed to the favorable radical 1,2-silyl transfer over the cyclization of alkoxy radicals to the olefins. The reaction shows broad substrate scope and wide functional-group tolerance. The synthetic potential of the methodology was demonstrated