3240-30-0Relevant academic research and scientific papers
ADDITION OF KETONE ENOLATES TO ?-ALLYLPALLADIUM COMPOUNDS. STEREOCHEMISTRY AND SCOPE OF THE REACTION
Akermark, Bjoern,Jutand, Anny
, p. C41 - C43 (1981)
Conditions have been developed for the addition of ketone enolates to ?-allylpalladium systems.A stereochemical study has shown that the enolate adds from the face of the ?-allyl system opposite to palladium.
α- And β-Functionalized Ketones from 1,3-Dienes and Aldehydes: Control of Regio- And Enantioselectivity in Hydroacylation of 1,3-Dienes
Parsutkar, Mahesh M.,Rajanbabu, T. V.
supporting information, p. 12825 - 12835 (2021/08/30)
Ketones are among the most widely used intermediates in organic synthesis, and their synthesis from inexpensive feedstocks could be quite impactful. Regio- and enantioselective hydroacylation reactions of dienes provide facile entry into useful ketone-bearing chiral motifs with an additional latent functionality (alkene) suitable for further elaboration. Three classes of dienes, 2- or 4-monosubstituted and 2,4-disubstituted 1,3-dienes, undergo cobalt(I)-catalyzed regio- and enantioselective hydroacylation, giving products with high enantiomeric ratios (er). These reactions are highly dependent on the ligands, and we have identified the most useful ligands and reaction conditions for each class of dienes. 2-Substituted and 2,4-disubstituted dienes predominantly undergo 1,2-addition, whereas 4-substituted terminal dienes give highly enantioselective 4,1- or 4,3-hydroacylation depending on the aldehyde, aliphatic aldehydes giving 4,1-addition and aromatic aldehydes giving 4,3-addition. Included among the substrates are feedstock dienes, isoprene (US$1.4/kg) and myrcene (US$129/kg), and several common aldehydes. We propose an oxidative dimerization mechanism that involves a Co(I)/Co(III) redox cycle that appears to be initiated by a cationic Co(I) intermediate. Studies of reactions using isolated neutral and cationic Co(I) complexes confirm the critical role of the cationic intermediates in these reactions. Enantioselective 1,2-hydroacylation of 2-trimethylsiloxy-1,3-diene reveals a hitherto undisclosed route to chiral siloxy-protected aldols. Finally, facile syntheses of the anti-inflammatory drug (S)-Flobufen (2 steps, 92% yield, >99:1 er) and the food additive (S)-Dihydrotagetone (1 step, 83% yield; 96:4 er) from isoprene illustrate the power of this method for the preparation of commercially relevant compounds.
Water-Accelerated Nickel-Catalyzed α-Crotylation of Simple Ketones with 1,3-Butadiene under pH and Redox-Neutral Conditions
Chen, Tiantian,Dong, Guangbin,Xing, Dong,Yang, Haijian,Yang, Yang
, p. 4238 - 4243 (2020/05/05)
We report a nickel/NHC-catalyzed branched-selective α-crotylation of simple ketones using 1,3-butadiene as the alkylation agent. This reaction is regioselective and operated under pH and redox-neutral conditions. Water was used as the sole additive, which significantly accelerates the transformation.
gamma-alkenyl ketone and preparation method thereof
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Paragraph 0031; 0049-0051, (2020/02/29)
The invention discloses a gamma-alkenyl ketone preparation method, wherein the target product can be obtained at high yield and high regioselectivity by using acetophenone and 1,3-butadiene as raw materials in the presence of an organic solvent, a catalyst, an additive and a ligand. According to the invention, the method has advantages of high atom economy, high regioselectivity, high yield and the like, can achieve the efficient conversion from a cheap basic organic chemical product 1,3-butadiene to high-added-value gamma-alkenyl ketone, and uses the cheap catalyst, so that the reaction conditions are neutral and mild, and the experimental operation is safe and simple; and the synthesized gamma-alkenyl ketone is a useful synthetic intermediate, can be subjected to a series of conversionsto obtain a series of drug molecule precursors or key intermediates, and has wide application prospect.
Ketone Synthesis by Direct, Orthogonal Chemoselective Hydroacylation of Alkenes with Amides: Use of Alkenes as Surrogates of Alkyl Carbanions
Geng, Hui,Huang, Pei-Qiang
supporting information, (2019/07/08)
Direct functionalization of alkenes and direct transformation of carboxamides are two exciting areas that have attracted considerable attention in recent years. We report herein that secondary amides, the least reactive derivatives of carbonyl compounds, upon activated with triflic anhydride, can serve as effective hydroacylating reagents in partner with alkenes to yield ketones at ambient temperature. The method was applied to the one-step synthesis of racemic dihydro-ar-turmerone. In this method, alkenes serve as surrogates of organometallic reagents, which allows the orthogonal chemoselective reactions. The ready availability of many olefins such as camphene and norbornene permits one-step ketone synthesis that would require several steps by conventional methods.
Enolonium Species—Umpoled Enolates
Arava, Shlomy,Kumar, Jayprakash N.,Maksymenko, Shimon,Iron, Mark A.,Parida, Keshaba N.,Fristrup, Peter,Szpilman, Alex M.
supporting information, p. 2599 - 2603 (2017/02/26)
Enolonium species/iodo(III)enolates of carbonyl compounds have been suggested to be intermediates in a wide variety of hypervalent iodine induced chemical transformations of ketones, including α-C?O, α-C?N, α-C?C, and α-carbon–halide bond formation, but they have never been characterized. We report that these elusive umpoled enolates may be made as discrete species that are stable for several minutes at ?78 °C, and report the first spectroscopic identification of such species. It is shown that enolonium species are direct intermediates in C?O, C?N, C?Cl, and C?C bond forming reactions. Our results open up chemical space for designing a variety of new transformations. We showcase the ability of enolonium species to react with prenyl, crotyl, cinnamyl, and allyl silanes with absolute regioselectivity in up to 92 % yield.
Iridium-catalyzed enantioselective allylation of silyl enol ethers derived from ketones and α,β-unsaturated ketones
Liang, Xiao,Wei, Kun,Yang, Yu-Rong
supporting information, p. 17471 - 17474 (2015/12/09)
The unified Ir-catalyzed enantioselective allylic substitution reactions of silyl enol ethers derived from ketones and α,β-unsaturated ketones with branched, racemic allylic alcohols are described. This transformation is catalyzed by the Carreira system and proceeds without fluoride, and with high ee and b:l ratio. The synthetic utility of this method was illustrated by the concise enantioselective total synthesis of marine natural products calyxolane A, B and by the assignment of the absolute configuration of calyxolane A.
Regioselective hydroacylation of 1,3-dienes by cobalt catalysis
Chen, Qing-An,Kim, Daniel K.,Dong, Vy M.
supporting information, p. 3772 - 3775 (2014/04/03)
We describe a cobalt-catalyzed hydroacylation of 1,3-dienes with non-chelating aldehydes. Aromatic aldehydes provide 1,4-addition products as the major isomer, while aliphatic aldehydes favor 1,2-hydroacylation products. The kinetic profile supports an oxidative cyclization mechanism involving a cobaltacycle intermediate that undergoes transformation with high regio- and stereoselectivity.
Pd-catalyzed domino carbonylative-decarboxylative allylation: An easy and selective monoallylation of ketones
Giboulot, Steven,Liron, Frederic,Prestat, Guillaume,Wahl, Benoit,Sauthier, Mathieu,Castanet, Yves,Mortreux, Andre,Poli, Giovanni
supporting information; experimental part, p. 5889 - 5891 (2012/07/28)
In the presence of an allyl alcohol, α-chloroacetophenones undergo an allyloxycarbonylation reaction followed by in situ decarboxylative allylation to selectively afford the corresponding monoallylated ketones via a Pd-catalyzed domino sequence. The scope of the reaction was extended to substituted α-chloroacetophenones as well as various allyl alcohols.
Cross-coupling reaction of α-chloroketones and organotin enolates catalyzed by zinc halides for synthesis of γ-diketones
Yasuda, Makoto,Tsuji, Shoki,Shigeyoshi, Yusuke,Baba, Akio
, p. 7440 - 7447 (2007/10/03)
The reaction of tin enolates 1 with α-chloro- or bromoketones 2 gave γ-diketones (1,4-diketones) 3 catalyzed by zinc halides. In contrast to the exclusive formation of 1,4-diketones 3 under catalytic conditions, uncatalyzed reaction of 1 with 2 gave aldol-type products 4 through carbonyl attack. NMR study indicates that the catalyzed reaction includes precondensation between tin enolates and α-haloketones providing an aldol-type species and their rearrangement of the oxoalkyl group with leaving halogen to produce 1,4-diketones. The catalyst, zinc halides, plays an important role in each step. The carbonyl attack for precondensation is accelerated by the catalyst as Lewis acid and the intermediate zincate promotes the rearrangement by releasing oxygen and bonding with halogen. Various types of tin enolates and α-chloro and bromoketones were applied to the zinc-catalyzed cross-coupling. On the other hand, the allylic halides, which have no carbonyl moiety, were inert to the zinc-catalyzed coupling with tin enolates. The copper halides showed high catalytic activity for the coupling between tin enolates 1 and organic halides 7 to give γ,δ-unsaturated ketones 8 and/or 9. The reaction with even chlorides proceeded effectively by the catalytic system.
