作者:Peter J. Rayner、Giacomo Gelardi、Peter O'Brien、Richard A. J. Horan、David C. Blakemore
DOI:10.1039/c4ob00567h
日期:——
speculated that four other α-amino sulfoxides were synthesised but could not be isolated due to their propensity to α-eliminate the sulfoxide. Ultimately, a stable, cyclic N-Boc α-amino sulfoxide was prepared and this successful synthesis relied on the α-amino sulfoxide being part of a bicyclic [3.1.0] fusedring system that could not undergo α-elimination of the sulfoxide.
Ligand-Enabled Enantioselective Csp3
-H Activation of Tetrahydroquinolines and Saturated Aza-Heterocycles by Rh<sup>I</sup>
作者:Steffen Greßies、Felix J. R. Klauck、Ju Hyun Kim、Constantin G. Daniliuc、Frank Glorius
DOI:10.1002/anie.201805680
日期:2018.7.26
The first rhodium(I)‐catalyzedenantioselective intermolecular C–Hactivation of various saturated aza‐heterocycles including tetrahydroquinolines, piperidines, piperazines, azetidines, pyrrolidines, and azepanes is presented. The combination of a rhodium(I) precatalyst and a chiral monodentate phosphonite ligand is shown to be a powerful catalytic system to access a variety of important enantio‐enriched
α- and α′-Lithiation–Electrophile Trapping of <i>N</i>-Thiopivaloyl and <i>N</i>-<i>tert</i>-Butoxythiocarbonyl α-Substituted Azetidines: Rationalization of the Regiodivergence Using NMR and Computation
作者:Kelvin E. Jackson、Claire L. Mortimer、Barbara Odell、Jeffrey M. McKenna、Timothy D. W. Claridge、Robert S. Paton、David M. Hodgson
DOI:10.1021/acs.joc.5b01804
日期:2015.10.16
H-1 NMR and computational analyses provide insight into the regiodivergent (alpha- and alpha'-) lithiation-electrophile trapping of N-thiopivaloyl- and N-(tert-butoxythio-carbonyl)-alpha-alkylazetidines. The magnitudes of the rotation barriers in these azetidines indicate that rotamer interconversions do not occur at the temperature and on the time scale of the lithiations. The NMR and computational studies support the origin of regioselectivity as being thiocarbonyl-directed lithiation from the lowest energy amide-like rotameric forms (cis for N-thiopivaloyl and trans for N-tert-butoxythiocarbonyl).