4458-64-4Relevant articles and documents
Enantioselective Synthesis of Cyclopropanone Equivalents and Application to the Formation of Chiral β-Lactams
Jang, Yujin,Johnson, J. Drake,Jung, Myunggi,Lindsay, Vincent N. G.,Poteat, Christopher M.,Williams, Rachel G.
supporting information, p. 18655 - 18661 (2020/08/21)
Cyclopropanone derivatives have long been considered unsustainable synthetic intermediates because of their extreme strain and kinetic instability. Reported here is the enantioselective synthesis of 1-sulfonylcyclopropanols, as stable yet powerful equivalents of the corresponding cyclopropanone derivatives, by α-hydroxylation of sulfonylcyclopropanes using a bis(silyl) peroxide as the electrophilic oxygen source. This work constitutes the first general approach to enantioenriched cyclopropanone derivatives. Both the electronic and steric nature of the sulfonyl moiety, which serves as a base-labile protecting group and confers crystallinity to these cyclopropanone precursors, were found to have a crucial impact on the rate of equilibration to the corresponding cyclopropanone. The utility of these cyclopropanone surrogates is demonstrated in a mild and stereospecific formal [3+1] cycloaddition with simple hydroxylamines, leading to the efficient formation of chiral β-lactam derivatives.
RuO4-mediated oxidation of N-benzylated tertiary amines. Four- And three-membered azacycloalkanes as substrates
Florea, Cristina A.,H?rtopeanu, Anca,Stavarache, Cristina,Petride, Horia
, p. 294 - 307 (2018/11/26)
Similarly to N-benzylpiperidine and -pyrrolidine, N-benzylazetidine underwent RuO4-catalyzed oxidation by attack at both types of N-methylene C-H bonds: Endocyclic and exocyclic (benzylic). If the reaction is performed in the presence of cyanide, α-aminon
Reductive alkylation of thioamides with Grignard reagents in the presence of Ti(O i Pr)4: Insight and extension
Hermant, Fabien,Urbaska, Ewelina,Seizilles De Mazancourt, Sarah,Maubert, Thomas,Nicolas, Emmanuel,Six, Yvan
supporting information, p. 5643 - 5653 (2015/02/19)
The reductive alkylation of thioamides by Grignard reagents in the presence of Ti(OiPr)4 is the subject of a study involving 20 different substrates. The influence of various parameters has been evaluated, showing notably that the yields of this moderately efficient process can be improved in several cases by applying a slow addition of the Grignard reagent. The results presented in this contribution also provide new insight into the reactivity of the proposed key intermediates, namely, a metalated iminium species and, ultimately, an α-metalated amine. Interestingly, by control of the temperature and the amount of Grignard reagent engaged, the reaction can be directed toward the selective formation of the former titanium intermediate complex. This represents an extension of the original method, allowing the synthesis of various previously inaccessible substituted amines by subsequent addition of a nucleophilic reagent. This role can be played not only by organomagnesium compounds but also by alkyllithium reagents, alkyltitanium(IV) complexes, and lithium aluminum hydride. The properties of the α-metalated amine final intermediate have also been explored, demonstrating that this complex is a poor nucleophile but can act as a radical precursor, which is especially evidenced when the resulting radical species are stabilized. Overall, this chemistry thus proves unexpectedly rich and can plausibly lay the basis for the development of new applications in the future.
