28384-49-8Relevant academic research and scientific papers
Superacid-catalyzed electrocyclization of 1-phenyl-2-propen-1-ones to 1- indanones. Kinetic and theoretical studies of electrocyclization of oxonium- carbenium dications
Suzuki, Takayoshi,Ohwada, Tomohiko,Shudo, Koichi
, p. 6774 - 6780 (1997)
Strongly acidic conditions are required to induce the Nazarov-type cyclization of aryl vinyl ketones, although chemical analogy with the Nazarov reaction would superficially imply a straightforward electrocyclization reaction of the O-protonated monocation. In this paper we describe the superacid-catalyzed prototype cyclization of 1-phenyl-2-propen-1-ones. The acidity dependence of these cyclization reactions as revealed by kinetic measurements strongly suggests the involvement of the O,O-diprotonated dication rather than the O-protonated monocation. That is the cyclization of 1-phenyl-2-propen-1-ones represents an electrocyclization of the oxonium- carbenium dication. We also describe the effect of substituents at the 2- position of 1-phenyl-2-propen-1-ones. Ab initio calculations, based on the density functional theory, support the idea that electrocyclization of the dication is energetically more favarable than that of the monocation.
Iron-Catalyzed Enantioselective Radical Carboazidation and Diazidation of α,β-Unsaturated Carbonyl Compounds
Dong, Shunxi,Feng, Xiaoming,He, Jun,Liu, Wen,Liu, Xiaohua,Pu, Maoping,Wu, Yun-Dong,Zhang, Tinghui
, p. 11856 - 11863 (2021/08/16)
Azidation of alkenes is an efficient protocol to synthesize organic azides which are important structural motifs in organic synthesis. Enantioselective radical azidation, as a useful strategy to install a C-N3 bond, remains challenging due to the inherently instability and unique structure of radicals. Here, we disclose an efficient enantioselective radical carboazidation and diazidation of α,β-unsaturated ketones and amides catalyzed by chiral N,N′-dioxide/Fe(OTf)2 complexes. An array of substituted alkenes was transformed to the corresponding α-azido carbonyl derivatives in good to excellent enantioselectivities, benefiting the preparation of chiral α-amino ketones, vicinal amino alcohols, and vicinal diamines. Control experiments and mechanistic studies proved the radical pathway in the reaction process. The DFT calculations showed that the azido transferred to the radical intermediate via an intramolecular five-membered transition state with the internal nitrogen of the Fe-N3 species.
Direct α-Acylation of Alkenes via N-Heterocyclic Carbene, Sulfinate, and Photoredox Cooperative Triple Catalysis
Liu, Kun,Studer, Armido
supporting information, p. 4903 - 4909 (2021/05/04)
N-Heterocyclic carbene (NHC) catalysis has emerged as a versatile tool in modern synthetic chemistry. Further increasing the complexity, several processes have been introduced that proceed via dual catalysis, where the NHC organocatalyst operates in concert with a second catalytic moiety, significantly enlarging the reaction scope. In biological transformations, multiple catalysis is generally used to access complex natural products. Guided by that strategy, triple catalysis has been studied recently, where three different catalytic modes are merged in a single process. In this Communication, direct α-C-H acylation of various alkenes with aroyl fluorides using NHC, sulfinate, and photoredox cooperative triple catalysis is reported. The method allows the preparation of α-substituted vinyl ketones in moderate to high yields with excellent functional group tolerance. Mechanistic studies reveal that these cascades proceed through a sequential radical addition/coupling/elimination process. In contrast to known triple catalysis processes that operate via two sets of interwoven catalysis cycles, in the introduced process, all three cycles are interwoven.
Metal-free, one-pot, sequential protocol for transforming ,-epoxy ketones to -hydroxy ketones and -methylene ketones
Hasegawa, Eietsu,Arai, Saki,Tayama, Eiji,Iwamoto, Hajime
, p. 1593 - 1600 (2015/02/19)
A new sequential, one-pot protocol for transforming 1,3-disubstituted 2,3-epoxy ketones to β;-hydroxy ketones and α-methylene ketones has been developed. Reaction of epoxy ketones with boron trifluoride etherate (BF3·OEt2) generates the cationic intermediates by regioselective epoxide ring opening and an acyl shift. Then, a treatment of these cations with 2-aryl-1,3-dimethylbenzimidazolines (DMBIH) results in formation of 1,2-disubstituted 3-hydroxy ketones. DMBIH serves as a hydride donor in the second step of this process. Finally, the β;-hydroxy ketones can be converted to 1,2-disubstituted 2-methylene ketones by treatment with methanesulfonic acid or a combination of methanesulfonyl chloride and triethylamine. Importantly, the sequential steps involved in formation of the α-methylene ketone products can be carried out in one pot.
The Chemistry of Aryllead Tricarboxylates. Synthesis of Some α-Aryl α,β-Unsaturated Carbonyl Compounds
Kopinski, Richard P.,Pinhey, John T.
, p. 311 - 316 (2007/10/02)
The treatment of 4-benzoyltetrahydrofuran-2,3-dione (2a) with 2 equiv. of phenyllead triacetate (3a) in chloroform gives 1,2-diphenylpropenone (4a) in excellent yield.This reaction has been investigated with a number of similar derivatives of tetrahydrofuran-2,3-dione and a number of aryllead triacetates.It has been found to be very sensitive to the nature of the substituent at C4, and it would appear to be limited to the synthesis of α-methylene carbonyl compounds since a 5-methyl substituent inhibits the reaction.
