Condensationsproducte der Tetronsäure

Wolff, Ludwig

doi:10.1002/jlac.19023220304

Cited by 42 publications

(16 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A classic method for the synthesis of primary anilines is the Semmler-Wolff reaction, 49–51 which involves high-temperature dehydration of cyclohexenone oximes promoted by strong acid (Scheme 26A). The harsh conditions (e.g., refluxing Ac 2 O/AcOH with anhydrous HCl) limit its synthetic utility, and the reactions are complicated by competing formation of Beckmann rearrangement products and acylation of the aniline products.…”

Section: Dehydrogenative Coupling Of Cyclohexanones/cyclohexenonesmentioning

confidence: 99%

Palladium-Catalyzed Aerobic Dehydrogenation of Cyclic Hydrocarbons for the Synthesis of Substituted Aromatics and Other Unsaturated Products

2016

View full text Add to dashboard Cite

Catalytic dehydrogenation of saturated or partially saturated six-membered carbocycles into aromatic rings represents an appealing strategy for the synthesis of substituted arenes. Particularly effective methods have been developed for the dehydrogenation of cyclohexanones and cyclohexenes into substituted phenol, aniline, and benzene derivatives, respectively. In this Perspective, we present the contributions of our research group to the discovery and development of palladium-based catalysts for aerobic oxidative dehydrogenation methods, including general methods for conversion of cyclohexanones and cyclohexenones into substituted phenols and a complementary method for partial dehydrogenation cyclohexanones to cyclohexenones. The mechanistic basis for chemoselective conversion of cyclohexanones to phenols or enones is presented. These results are presented within the context of recent methods developed by others for the synthesis of aryl ethers, anilines and other substituted arenes. Overall, Pd-catalyzed dehydrogenation methods provide a compelling strategy for selective synthesis of aromatic and related unsaturated molecules.

show abstract

Section: Dehydrogenative Coupling Of Cyclohexanones/cyclohexenonesmentioning

confidence: 99%

Palladium-Catalyzed Aerobic Dehydrogenation of Cyclic Hydrocarbons for the Synthesis of Substituted Aromatics and Other Unsaturated Products

2016

View full text Add to dashboard Cite

show abstract

“…The dehydrative aromatization of cyclohexenone oximes to primary anilines, known as the Semmler–Wolff reaction, is another attractive method for the synthesis of substituted primary anilines with high ortho / meta / para selectivities because of the easy availability of cyclohexenone oximes with various substituted patterns on cyclohexenyl rings through dehydrative condensation of cyclohexenones and hydroxylamine . Despite its great potential for the synthesis of substituted primary anilines, the Semmler–Wolff reaction has rarely been utilized in organic synthesis due to its harsh reaction conditions (e.g., refluxing in AcOH/Ac 2 O with HCl gas), which leads to the narrow substrate scope and generally low yields and selectivities (Scheme d) . A heterogeneous Pd/C catalyst has been reported to promote the Semmler–Wolff reaction under high reaction temperatures (e.g., 188 °C) with the substrate scope limited to cyclohexenone oximes (Scheme d) .…”

Section: Introductionmentioning

confidence: 99%

Selective Synthesis of Primary Anilines from Cyclohexanone Oximes by the Concerted Catalysis of a Mg–Al Layered Double Hydroxide Supported Pd Catalyst

et al. 2017

View full text Add to dashboard Cite

Although the selective conversion of cyclohexanone oximes to primary anilines would be a good complement to the classical synthetic methods for primary anilines, which utilize arenes as the starting materials, there have been no general and efficient methods for the conversion of cyclohexanone oximes to primary anilines until now. In this study, we have successfully realized the efficient conversion of cyclohexanone oximes to primary anilines by utilizing a Mg-Al layered double hydroxide supported Pd catalyst (Pd(OH)/LDH) under ligand-, additive-, and hydrogen-acceptor-free conditions. The substrate scope was very broad with respect to both cyclohexanone oximes and cyclohexenone oximes, which gave the corresponding primary anilines in high yields with high selectivities (17 examples, 75% to >99% yields). The reaction could be scaled up (gram-scale) with a reduced amount of the catalyst (0.2 mol %). Furthermore, the one-pot synthesis of primary anilines directly from cyclohexanones and hydroxylamine was also successful (five examples, 66-99% yields). The catalysis was intrinsically heterogeneous, and the catalyst could be reused for the conversion of cyclohexanone oxime to aniline at least five times with keeping its high catalytic performance. Kinetic studies and several control experiments showed that the high activity and selectivity of the present catalyst system were attributed to the concerted catalysis of the basic LDH support and the active Pd species on LDH. The present transformation of cyclohexanone oximes to primary anilines proceeds through a dehydration/dehydrogenation sequence, and herein the plausible reaction mechanism is proposed on the basis of several pieces of experimental evidence.

show abstract

“…Oximes can be readily prepared, and these compounds are generally nontoxic and nonexplosive, stable to air and moisture, easy to store, and simple to handle. Due to the relatively low energy of the N–O bond, the oximes can participate in various transformations involving N–O bond cleavage, such as a Beckmann rearrangement, a Neber rearrangement, and a Semmler–Wolff reaction . Much recent attention has been paid to transition-metal catalysis, since many transition metals can efficiently trigger oxime N–O bond cleavage to generate iminyl radicals or imino-metal intermediates by means of oxidative addition or single electron transfer (SET) pathways. , …”

Section: Introductionmentioning

confidence: 99%

Copper-Catalyzed Intermolecular Cyclization between Oximes and Alkenes: A Facile Access to Spiropyrrolines

et al. 2017

View full text Add to dashboard Cite

A Cu-catalyzed protocol has been developed for the rapid construction of a wide spectrum of structurally interesting spiropyrroline skeletons. This method utilizes readily accessible ketoximes and alkenes as the starting materials and exhibits broad substrate scope and good functional group compatibility. Furthermore, the reaction can be applied for the late-stage modification of bioactive pregnenolone derivatives. The mechanistic investigation suggests that the reactions proceed through a radical process.

show abstract

Condensationsproducte der Tetronsäure

Cited by 42 publications

References 17 publications

Palladium-Catalyzed Aerobic Dehydrogenation of Cyclic Hydrocarbons for the Synthesis of Substituted Aromatics and Other Unsaturated Products

Palladium-Catalyzed Aerobic Dehydrogenation of Cyclic Hydrocarbons for the Synthesis of Substituted Aromatics and Other Unsaturated Products

Selective Synthesis of Primary Anilines from Cyclohexanone Oximes by the Concerted Catalysis of a Mg–Al Layered Double Hydroxide Supported Pd Catalyst

Copper-Catalyzed Intermolecular Cyclization between Oximes and Alkenes: A Facile Access to Spiropyrrolines

Contact Info

Product

Resources

About