78698-19-8Relevant academic research and scientific papers
Stereocontrolled aziridination of imines via a sulfonium ylide route and a mechanistic study
Yang, Xiao-Fang,Zhang, Ming-Jie,Hou, Xue-Long,Dai, Li-Xin
, p. 8097 - 8103 (2002)
The reaction of N-diphenylphosphinoyl imines 1 with [3- (trimethylsilyl)allyl]dimethylsulfonium bromide (5) in the presence of NaH at room temperature predominantly gave trans-vinylaziridines 4. On the other hand, cis-vinylaziridines 4 were the main products when the preformed ylide prepared from the reaction of [3-(trimethylsilyl)allyl]diphenylsulfonium perchlorate (6) was reacted with the same imines 1 at low temperature. trans-Aziridines were also obtained when imines 1 and sulfinimines 9 were reacted with N,N-dimethylacetamide-2-dimethylsulfonium bromide (7) in the presence of a base, respectively. A mechanistic study showed that the stereochemistry of these reactions was controlled by the reactivity of the imines and ylides. A higher reactivity of imines and ylides favors the formation of cis-aziridines, whereas a lower reactivity leads to trans-products.
Development of Chiral Ureates as Chiral Strong Br?nsted Base Catalysts
Ishikawa, Sho,Kondoh, Azusa,Terada, Masahiro
supporting information, p. 3724 - 3728 (2020/03/11)
Recently, chiral Br?nsted bases having high basicity have emerged as a powerful tool in developing new catalytic enantioselective reactions. However, such chiral strong Br?nsted base catalysts are still very scarce. Herein, we report the development of a chiral anionic Br?nsted base having a N,N′-dialkyl ureate moiety as a basic site. Its prominent catalytic activity was demonstrated in the enantioselective addition reactions of α-thioacetamides as less acidic pronucleophiles with various electrophiles. Thus, the newly developed chiral catalyst with high accessibility and structural tunability would expand the scope of viable enantioselective transformations under Br?nsted base catalysis.
Cu(I)/chiral bisoxazoline-catalyzed enantioselective sommelet-hauser rearrangement of sulfonium ylides
Wang, Jianbo,Li, Shu-Sen
supporting information, p. 12343 - 12358 (2020/11/10)
Catalytic asymmetric thia-Sommelet-Hauser rearrangement of sulfonium ylides remains a great challenge due to its multistep reaction mechanism involving metal carbene formation, proton transfer, and [2,3]-sigmatropic rearrangement. In particular, the key problem of such reactions is the differentiation of the enantiotopic lone pair electrons of sulfur, which generates the sulfonium ylide intermediate bearing chirality on the sulfur atom. With a modified chiral bisoxazoline ligand, we developed a Cu(I)- catalyzed asymmetric thia-Sommelet-Hauser rearrangement with good to excellent enantioselectivities. Mechanistic studies provide insights into the details of the reaction mechanism.
Direct access to α-sulfenylated amides/esters: Via sequential oxidative sulfenylation and C-C bond cleavage of 3-oxobutyric amides/esters
Jiang, Yi,Deng, Jie-Dan,Wang, Hui-Hong,Zou, Jiao-Xia,Wang, Yong-Qiang,Chen, Jin-Hong,Zhu, Long-Qing,Zhang, Hong-Hua,Peng, Xue,Wang, Zhen
supporting information, p. 802 - 805 (2018/02/06)
An efficient, environmentally benign and unprecedented synthesis of various α-sulfenylated amides/esters has been developed under oxygen atmosphere. The reaction shows good functional group tolerance and excellent chemo/regioselectivity. All the desired products were obtained in moderate to excellent yields, even on the gram scale. Practically, the related α-thiol Weinreb amide can be readily transferred to a series of prospective compounds, and selenium atom can be introduced to the α-sites of the amides in high yields.
Direct catalytic formation of primary and tertiary amides from non-activated carboxylic acids, employing carbamates as amine source
Tinnis, Fredrik,Lundberg, Helena,Adolfsson, Hans
supporting information, p. 2531 - 2536 (2012/11/06)
The operationally simple titanium(IV)- or zirconium(IV)-catalyzed direct amidation of non-activated carboxylic acids with ammonium carbamates generates primary, and tertiary N,N-dimethyl-substituted amides in good to excellent yields. Copyright
Substituent-dictated partitioning of intermediates on the sulfide singlet oxygen reaction surface. A new mechanism for oxidative C-S bond cleavage in α-hydroperoxy sulfides
Toutchkine,Aebisher,Clennan
, p. 4966 - 4973 (2007/10/03)
The reactions of singlet oxygen with 17 sulfides bearing either anion or radical stabilizing substituents are reported. The abilities of substituents to modify product compositions in both the oxidative cleavage and sulfide oxidation pathways are analyzed in terms of partitioning of the hydroperoxy sulfonium ylide intermediate. Evidence is presented that suggests that the hydroperoxy sulfonium ylide exists in both diradical and zwitterionic forms. In addition, both inter- and intramolecular pathways for decomposition of α-hydroperoxy sulfides are suggested to rationalize the substituent-dependent formation of oxidative C-S bond cleavage products.
Homolytic bond dissociation enthalpies of the acidic H - A bonds caused by proximate substituents in sets of methyl ketones, carboxylic esters, and carboxamides related to changes in ground state energies
Bordwell,Zhang, Shizhong,Zhang, Xian-Man,Liu, Wei-Zhong
, p. 7092 - 7096 (2007/10/02)
Equilibrium acidities in DMSO were measured for the N-H bonds in 15 carboxamides, and the homolytic bond dissociation enthalpies (BDEs) for these bonds were estimated. For the N-H bonds in five aliphatic carboxamides, the average pKHA is 25.5 a
Reaction of 1-Lithio-1-arylthio(or alkylthio)methyltrimethylsilane with Acid Derivatives. A Novel Synthesis of Functionalized Vinyl Sulfides
Agawa, Toshio,Ishikawa, Minori,Komatsu, Mitsuo,Ohshiro, Yoshiki
, p. 1205 - 1208 (2007/10/02)
Reactions of 1-lithio-1-phenylthiomethyl- (1a) and 1-lithio-1-methylthiomethyltrimethylsilane (1b) with amides, an ester, acid anhydrides, a urea, and a carbonate are described which provide useful routes to functionalized vinyl sulfides.The reaction of 1 with amides gave β-functionalized vinyl sulfides, 1-dialkylamino-2-phenylthio (or methylthio)ethylenes, in 40-95percent yields and the reaction could be extended to the sulfonyl derivatives of 1 to afford 1-dialkylamino-2-phenylsulfonyl(or methylsulfonyl)ethylenes.Although ethyl benzoate and some acid anhydrides were not good substrates for this reaction, tetramethylurea and diethyl carbonate gave α-functionalized vinyl sulfides, 1-amidovinyl- and 1-(ethoxycarbonyl)vinyl sulfides, in moderate yields when treated with 1a followed by addition of benzaldehyde.
