- General Method for the Asymmetric Synthesis of N-H Sulfoximines via C-S Bond Formation
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A versatile method for the synthesis of enantioenriched N-H sulfoximines is reported. The approach stems from the organomagnesium-mediated ring opening of novel cyclic sulfonimidate templates. The reactions proceed in high yield and with excellent stereofidelity with alkyl, aryl, and heteroaryl Grignard reagents. The chiral auxiliary is readily removed from the resultant sulfoximines via an unusual oxidative debenzylation protocol that utilizes molecular oxygen as the terminal oxidant. This provides a general strategy for the synthesis of highly enantioenriched N-H sulfoximines.
- Argent, Stephen P.,Lewis, William,Mendon?a Matos, Priscilla,Moore, Jonathan c.,Stockman, Robert A.
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supporting information
(2020/03/30)
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- Kinetic investigation on the hydrolysis of aryl(fluoro)(phenyl)-λ6-sulfanenitriles
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A kinetic investigation on the hydrolysis of aryl(fluoro)(phenyl)-λ6-sulfanenitriles was carried out in some aqueous and mixed aqueous-organic solutions. The pH-rate profiles showed that the hydrolysis consists of pH-independent, acidcatalyzed
- Dong,Fujii,Murotani,Dai,Ono,Morita,Shimasaki,Yoshimura
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p. 945 - 954
(2007/10/03)
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- Study of the mechanism for the hydrolysis of alkoxy(aryl)(phenyl)-λ6- sulfanenitriles, ArPhS(OR)(?N)
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The hydrolysis of alkoxy(aryl)(phenyl)-λ6-sulfanenitriles in several buffer solutions was found to follow a good pseudo-first-order kinetic equation, giving the corresponding sulfoximides and alcohols (for the case of the hydrolysis of neopentyloxy-λ6-sulfanenitrile, giving a rearranged product, 2-methyl-2-butanol). The dependence of the rate of hydrolysis on the structure of the alkyl group showed the opposite trend to the usual S(N)2 character, i.e. Me +] at pH more than 6.08, and trends to saturate at low pH. According to these kinetic results, a two-step reaction mechanism was proposed which involves a pre-equilibrium protonation on the nitrogen atom of the alkoxy-λ6- sulfanenitriles, followed by a rate-determining C-O bond cleavage via an S(N)2 or S(N)1 mechanism on the alkyl carbon atom depending on the structure of the alkyl group. From a double-reciprocal plot of 1/k(obs) vs. 1/[H+], the pK(a) value and the rate constant of the second reaction of neopentyloxy(diphenyl)-λ6-sulfanenitrile were estimated to be 5.02 and 7.02x10-3 s-1, respectively. The substituent effects on the phenyl group of neopentyloxy(diphenyl)-λ6-sulfanenitrile afforded a large negative p- value (-1.88) for pK(a) and positive one (+1.66) for the second reaction at 25.2 °C. The small negative p-values observed at pH 6.27 for diphenyl(propoxy)-λ6-sulfanenitrile (-0.42) and neopentyloxy(diphenyl)- λ6-sulfanenitrile (-0.26) were found to be the results of a cancellation of those for the opposite trend of the reactions of the pre-equilibrium and the second step. The activation parameters for both the pre-equilibrium and the subsequent reactions were also estimated based on the parameters for the hydrolysis of neopentyloxy(diphenyl)-λ6-sulfanenitrile at pH 6.22 and 2.99. The buffer effect is due to a nucleophilic attack of the buffer base to the alkyl carbon atom of the protonated alkoxy-λ6-sulfanenitriles. The sulfoximide moiety in the protonated λ6-sulfanenitrile is revealed to be a very good leaving group.
- Yoshimura, Toshiaki,Dong, Tiaoling,Fujii, Takayoshi,Ohkubo, Masanori,Sakuta, Mikiko,Wakai, Youko,Ono, Shin,Morita, Hiroyuki,Shimasaki, Choichiro
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p. 957 - 965
(2007/10/03)
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- Kinetic Study on the Alkaline Hydrolysis of S,S-Diaryl-N-halosulfilimines
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Kinetics for the alkaline hydrolysis of S,S-diaryl-N-bromosulfilimines were carried out in aqueous methanol.The observed pseudo-first-order rate constants were found to give a linear correlation with the concentration of sodium hydroxide, k=k1+k2.The first-order rate constants k1 showed a large negative Hammett ρ value (-2.43) for the substituent effect on the phenyl group, nearly zero activation entropy (-0.9+/-13.1 JK-1mol-1) and a relatively large m value (0.638) against the solvent ionizing power Y value suggesting that the reaction process fork1 close to SN1.The salt effect, the deuterium solvent isotope effect and the steric effect are also in accord with the SN1 mechanism.On the other hand, the second order rate constants k2 revealed a small Hammett ρ value, a negative activation entropy (-44.0+/-4.0 JK-1mol-1), a small m value (0.153) and a steric deceleration by ortho substituents showing that the reaction for k2 is SN2-like.The salt effect and the solvent isotope effect are also compatible with the SN2-like mechanism.Meanwhile, the k1 for S,S-diphenyl-N-halosulfilimines remarkably increased in the order of N-iodo N-bromo N-chloro.This reactivity might be due to the lone pair-lone pair repulsion at the reactant state.From these observations, the alkaline hydrolysis of S,S-diaryl-N-halosulfilimines was confirmed to proceed via concurrent two mechanisms, the SN1-like mechanism involving nitridosulfonium cation as an intermediate and the SN2'-like mechanism with the transition state in which the N-X bond cleavage is more progressed than the S-O bond formation with nucleophiles (-OH, -OMe).
- Yoshimura, Toshiaki,Tsukurimichi, Eiichi,Kita, Hiroshi,Fujii, Hiroshi,Shimasaki, Choichiro
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p. 1764 - 1769
(2007/10/02)
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- CONVENIENT PREPARATION AND SPECTROSCOPIC STUDIES OF SULFOXIMINES AND SULFONEDIIMINES: N-CHLOROSULFILIMINE AS KEY INTERMEDIATE
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N-Unsubstituted sulfilimines, when reacted with sodium hypochlorite in an aqueous alkaline methanol solution or with Chloramine-T in dry acetonitrile in the presence of excess sodium salt of tosylamide were converted to the corresponding N-unsubstituted s
- Furukawa, Naomichi,Akutagawa, Kunihiko,Oae, Shigeru
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- A FACILE CONVERSION OF SULFOXIMINES AND SULFONEDIIMINES TO SULFOXIDES AND SULFILIMINES WITH TERT-BUTYL NITRITE
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N-Unsubstituted sulfoximines and N-mono-tosylsulfonediimines were found to react readily with tert-butyl nitrite to give the corresponding sulfoxides and N-tosylsulfilimines in high yields with no racemization.
- Akutagawa, Kunihiko,Furukawa, Naomichi,Oae, Shigeru
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p. 369 - 374
(2007/10/02)
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- REDUCTIVE DEIMINATION OF SULFOXIMIDES AND SULFIMIDES WITH P-TOLUENESULFONYL NITRITE AND T-BUTYL THIONITRATE
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Reduction of sulfimides and sulfoximides with p-toluenesulfonyl nitrite, a new nitrosating agent, gave nearly quantitatively the corresponding deimination products, sulfides and sulfoxides, respectively.In the reaction of dialkyl and aryl alkyl sulfoximides with t-butyl thionitrate, N-t-butylthiosulfoximides were obtained besides the usual deimination products, although diaryl sulfoximides were readily deiminated to the corresponding sulfoxides in good yields in the same treatment. t-Butyl thionitrsate was also found to deiminate diphenyl sulfimide to give diphenyl sulfide in good yield.Sulfoximides reacted sluggishly with t-butyl thionitrite, however, eventually affording a small amount of sulfoxides.
- Oae, Shigeru,Iida, Kazuyuki,Takata, Toshikazu
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p. 103 - 114
(2007/10/02)
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