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
Development of Chiral Ureates as Chiral Strong Brønsted Base Catalysts
作者:Azusa Kondoh、Sho Ishikawa、Masahiro Terada
DOI:10.1021/jacs.9b13922
日期:2020.2.26
Recently, chiralBrønsted bases having high basicity have emerged as a powerful tool in developing new catalytic enantioselective reactions. However, such chiral strong Brønsted base catalysts are still very scarce. Herein, we report the development of a chiral anionic Brønsted base having a N,N'-dialkyl ureate moiety as a basic site. Its prominent catalytic activity was demonstrated in the enantioselective
Allylation of prochiral C-nucleophiles catalyzed by the Pd(0)—(S)-(—)-BINAP complex
作者:A. V. Lozanova、T. M. Ugurchieva、V. V. Veselovsky
DOI:10.1007/s11172-008-0239-9
日期:2008.8
The allylation of prochiral C-nucleophiles catalyzed by the Pd(0)—(S)-(—)-BINAP complex (BINAP is 2,2′-bis(diphenylphosphino)-1,1′-binaphthyl) was studied. The enantioselectivity of the allylation was found to be low.
研究了 Pd(0)-(S)-(-)-BINAP 复合物(BINAP 是 2,2′-双(二苯基膦)-1,1′-联萘)催化的亲手性 C 核亲和剂的烯丙基化。发现烯丙基化的对映选择性较低。
The reactivity of N,N-dialkyl-N-(3-phenylsulfinyltetrahydrofuran-2-ylidene)ammonium bromide
作者:T. M. Ugurchieva、A. V. Lozanova、M. V. Zlokazov、V. V. Veselovsky
DOI:10.1007/s11172-007-0240-8
日期:2007.8
amide under the action of bromine afforded (3R*,5S*, SS*)-N-(5-bromomethyl-3-phenylsulfinyltetrahydrofuran-2-ylidene)-N,N-diisopropylammonium bromide. Its transformations under the conditions of hydrolysis, dehydrobromination, and hydridereduction were studied.
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
作者:F. G. Bordwell、Shizhong Zhang、Xian-Man Zhang、Wei-Zhong Liu
DOI:10.1021/ja00132a008
日期:1995.7
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 and the average BDE is 108 +/- 2 kcal/mol. Equilibrium acidities in DMSO of the C-H bonds for seven sets of acids in series of the type GCH(2)COCH(3), GCH(2)CO(2)Et, and GCH(2)CONR(2) and the oxidation potentials of their conjugate bases, E(ox)(A(-)), where G is H, Ph, PhS, 1,3-dithianyl, Me(3)N(+), Ph(3)P(+), or MeCO, are also reported. For every set, there is a progressive increase in PKHA and a smaller progressive cathodic shift of E(ox)(A(-)), which are associated with progressive small increases in the BDEs of the acidic C-H bonds. These increases in BDEs are believed to be associated with progressive decreases in ground state energies in the order ketone > ester > amide. These results conform to a general rule that structural changes in weak acids that decrease ground state energies will tend to increase the BDEs of acidic H-A bonds, and vice versa.