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1.
Barroso S Blay G Al-Midfa L Muñoz MC Pedro JR 《The Journal of organic chemistry》2008,73(16):6389-6392
Alpha'-arylsulfonyl enones are efficient bidentate dienophiles for the Cu(II)-bis(oxazoline) catalyzed enantioselective Diels-Alder reaction with a number of dienes, affording the corresponding products with good to high enantiomeric excesses. The resulting products can be alkylated and the sulfone removed, so alpha'-arylsulfonyl enones can be regarded as surrogates of simple monodentate enones, which are poor dienophiles with this catalytic system. 相似文献
2.
Bridgehead Substitution via Putative Norborn‐1‐en‐3‐ones: Application in the Synthesis of Complex Molecules
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Prof. Dr. Faiz Ahmed Khan Basavaraj M. Budanur Dr. Chava Sudheer 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(19):7021-7025
The base‐mediated formation of a bridgehead double bond in a bicyclo[2.2.1]heptane system (anit‐Bredt molecules) is described. The synthesis of exocyclic norbornyl enones by Wittig reaction of α‐diketones is reported. These enones and their Michael adducts are used as substrates for the generation of transient bridgehead enones and their trapping with MeOH and H2O. Bridgehead alcohols are easily synthesized from norbornyl enones and are exploited for the diversity oriented synthesis of frameworks of natural and unnatural products. 相似文献
3.
LUO San-Zhong WANG Peng G. CHENG Jin-Pei 《有机化学》2003,23(Z1):169-169
β-Substituted enones have been considered less reactive in Baylis-Hillman reaction. The reaction of cyclic enones is sluggish or does not occur at all under traditional conditions. Various catalysts have been developed to pro mote the reaction of cyclic enones but with limited success. In previous study, we found that imidazole can catalyze the Baylis-Hillman reaction involving cyclic enones in aqueous THF solution. [1] In our continued efforts, a variety of azole compounds were examined in Baylis-Hillman reaction. We found that the azoles act as effective catalysts in properly adjusted water solution. 相似文献
4.
LUO San-Zhong WANG Peng G. CHENG Jin-Pei 《有机化学》2003,23(Z1):168-168
β-Substituted enones have been considered less reactive in Baylis-Hillman reaction. The reaction of cyclicenones is sluggish or does not occur at all under traditional conditions. [1] Therefore, substituted cyclic enones havebeen less explored in Baylis-Hillman reaction due to the extremely low reactivity. In this communication, we reported Baylis-Hillman reaction of substituted cyclic enones using our previously developed conditions with imidazole as catalyst. The reaction proceeded smoothly in aqueous media affording the desired product with good yields and moderate diastereoselectivity. 相似文献
5.
Regio‐ and Stereoselective Conjugate Addition of Aldehydes to β‐Tosyl Enones under the Catalysis of a Binaphthyl‐Modified Chiral Amine
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Dr. Taichi Kano Hisashi Sugimoto Hiroki Maruyama Prof. Keiji Maruoka 《Angewandte Chemie (International ed. in English)》2015,54(29):8462-8465
A simple axially chiral amine catalyst promoted the regio‐, diastereo‐, and enantioselective conjugate addition of aldehydes to β‐tosyl enones, which serve as ynone surrogates. The adducts were readily converted by treatment with L‐selectride into less accessible enones with a γ stereogenic center. Such compounds cannot be prepared through the amine‐catalyzed conjugate addition of aldehydes to ynones. The obtained enones underwent further conjugate addition of diorganozinc compounds in the presence of a copper catalyst. 相似文献
6.
Vinylic hydrogens at the beta-position of enones were effectively substituted with alkyl groups in a one-pot procedure to afford beta-alkyl enones in good to high isolated yields by conjugate addition of higher-order dialkyl cyanocuprates to enones, followed by a reaction with N-tert-butylbenzenesulfinimidoyl chloride at -78 degree C. 相似文献
7.
8.
Herein we report the copper-catalyzed asymmetric conjugate addition of Grignard reagents to cyclic and acyclic enones, with SimplePhos as chiral ligands. A variety of Grignard reagents can be added to a range of cyclic and acyclic enones, with moderate to good enantioselectivities (ee’s up to 86%). 相似文献
9.
The K2CO3 (10 mol %)-catalyzed 1,4-addition reaction of diethyl malonate with various substituted 1,2-allenic ketones leading to polyfunctionalized beta,gamma-unsaturated enones 3 or 4 was studied. With 3-unsubstituted 1-substituted-1,2-allenyl ketones, the highly selective formation of beta,gamma-unsaturated enones 4 was observed; with 1,2-allenyl ketones bearing one or two 3-substituents in the allenyl group, only beta,gamma-unsaturated enones 3 with an unmigrated carbon-carbon double bond were produced; with 3-monosubstituted-1,2-allenyl ketones Z-beta,gamma-unsaturated enones 3 were formed with excellent stereoselectivity (E:Z > 96:4); with propadienyl ketones, mixtures of beta,gamma-unsaturated enones 3 and 4 were formed. alpha-Pyrone derivatives were synthesized via the K(2)CO(3)-catalyzed or -promoted reaction of 1,2-allenic ketones with diethyl malonate via a sequential Michael addition-carbon-carbon double bond migration-lactonization process. 相似文献
10.
Wang LC Luis AL Agapiou K Jang HY Krische MJ 《Journal of the American Chemical Society》2002,124(11):2402-2403
The utilization of enones as latent enolates enables regioselective enolate formation from chemically robust presursors. In this communication, we report a catalytic Michael cycloisomerization of bis(enones) under Morita-Baylis-Hillman conditions. Upon exposure to 10 mol % tributylphosphine, bis(enone) substrates afford both five- and six-membered ring products. Notably, unsymmetrical bis(enones) possessing sufficient steric or electronic bias yield single isomeric products. 相似文献
11.
Shlomy Arava Sourav K. Santra Gulab K. Pathe Raja Kapanaiah Alex M. Szpilman 《Angewandte Chemie (International ed. in English)》2020,59(35):15171-15175
Herein we report on the umpolung of Morita–Baylis–Hillman type intermediates and application to the α‐functionalization of enone C?H bonds. This reaction gives direct access to α‐chloro‐enones, 1,2‐diketones and α‐tosyloxy‐enones. The latter are important intermediates for cross‐coupling reaction and, to the best of our knowledge, cannot be made in a single step from enones in any other way. The proposed mechanism is supported by spectroscopic studies. The key initial step involves conjugate attack of an amine (DABCO or pyridine), likely assisted by hypervalent iodine acting as a Lewis acid leading to formation of an electrophilic β‐ammonium‐enolonium species. Nucleophilic attack by acetate, tosylate, or chloride anion is followed by base induced elimination of the ammonium species to give the noted products. Hydrolysis of α‐acetoxy‐enones lead to formation of 1,2‐diketones. The α‐tosyl‐enones participate in Negishi coupling reactions under standard conditions. 相似文献
12.
LUO San-Zhong WANG Peng G. CHENG Jin-Pei 《有机化学》2003,23(Z1):166-166
β-Substituted enones have been considered less reactive in Baylis-Hillman reaction. The reaction of cyclic enones is sluggish or does not occur at all under traditional conditions. Various catalysts have been developed to pro mote the reaction of cyclic enones but with limited success. In previous study, we found that imidazole can catalyze the Baylis-Hillman reaction involving cyclic enones in aqueous THF solution.[1] In our continued efforts, we screened a variety of imidazoles to develop superior catalyst, and we found that the reaction could be greatly accelerated by adjusting the pH value of the water solution. 相似文献
13.
β-(Trifluoromethyl) enones, easily obtained in few steps from commercially available methyl hemiketal of trifluoroacetaldehyde, react with electron-rich O- and N-containing heterocycles (furans and benzofurans, pyrroles and indoles, hydroxycoumarins), through a 1,4 addition, to give heterocycles bearing a functionalized side-chain. β-(chlorodifluoromethyl)enones and β-(pentafluoroethyl)enones behave in the same way. 相似文献
14.
The first intermolecular electrophilic dearomatization of halonaphthols with benzyl/allyl bromides is described. Halonaphthols are used as carbon-nucleophiles in dearomatization to form three-dimensional cyclic enones with excellent chemoselectivity, in which etherification of phenolic hydroxyl group could be restrained well by using cesium carbonate as the base. A wide range of cyclic enones is directly prepared from various substituted benzyl/allyl bromides and halonaphthols. Mechanistic inves... 相似文献
15.
A new regioselective approach to the synthesis of α-aryl enones is reported. This represents an important application of the Kuwajima-Urabe protocol toward the synthesis of this simple albeit complex functional array. Several α-aryl enones were synthesized by the palladium catalyzed arylation of triethylsilylenol ethers of enones with high regioselectivity and broad scope, utilizing sterically encumbered electron-rich phosphine ligands to drive the reaction. 相似文献
16.
《Tetrahedron: Asymmetry》2006,17(5):786-791
A chemoenzymatic synthesis of both enantiomers of the pharmacologically interesting α′-acetoxy and α′-hydroxy-α-methoxy cyclic enones starting from α-hydroxy cyclic enones is described. Protection of 1,2-diketones, manganese(III) acetate-mediated acetoxylation followed by enzyme-mediated hydrolysis of α′-acetoxy enones gives acetoxy enones 3a–d and hydroxy enones 4a–d with high enantiomeric excesses (up to 99%) and good yields. The transesterification of rac-4b in the presence of DMAP afforded (+)-4b and (−)-3b in high enantiomeric excesses (91–94%) and good chemical yields. 相似文献
17.
Cross-coupling of fluorenone and enones with TiCL4Mg led to γ-ketol derivatives resulting of a conjugate addition of the fluorenone dianion to enones. 相似文献
18.
Several enones are converted into their alpha-iodo derivatives in excellent yields and carbonylated with palladium catalysis in the presence of alcohol or amines to the alpha-carbonyl enones in satisfactory yields. 相似文献
19.
[reaction: see text] An efficient method for the hydrogenation of the carbon-carbon double bond in azulenoid and aromatic fused azulenoid enones without the use of hydrogen and a metal catalyst is reported. Treatment of a variety of azulenoid enones with cycloheptatriene and a protic acid in acetonitrile gave the corresponding beta-azulenyl ketone derivatives in excellent to moderate yield. In this reaction, cycloheptatriene acts as a hydride donor. 相似文献
20.
Transition metal-catalysed acylation of alpha,beta-unsaturated carbonyl compounds with acylstannanes
Shirakawa E Yamamoto Y Nakao Y Tsuchimoto T Hiyama T 《Chemical communications (Cambridge, England)》2001,(19):1926-1927
Acylstannanes were found to add to such alpha,beta-unsaturated carbonyl compounds as enones or ynoates in the presence of a nicel or palladium catalyst to give 2-stannyl-4-oxoalk-2-enoates or 1,4-diketones, whereas the three component coupling between acylstannanes, enones and aldehydes provided 2-hydroxymethyl 1,4-diketones. 相似文献