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1.
A metal‐free oxidative decarbonylative coupling of aliphatic aldehydes with various electron‐deficient heterocycles has been developed. This reaction is supposed to be realized via a Minisci‐type mechanism, based on the substrate scope, regioselectivity and radical trapping experiments. The ready availability of aliphatic aldehydes, metal‐free conditions and broad substrate scope should make this method attractive for the late‐stage alkylation of bioactive heterocycles.
2.
The N‐heterocyclic carbene (NHC)‐catalyzed oxidative amidation of aromatic aldehydes with amines in the presence of N‐bromosuccinimide (NBS) as an oxidant has been developed for the synthesis of amides. This amidation strategy is tolerant to both the electronic and the steric nature of the aryl aldehydes employed. The present methodology was extended to chiral amino acid derivatives to generate the corresponding amides in good yields and excellent ee values (>98%).
3.
Different to the borrowing hydrogen strategy in which alcohols were activated by transition metal‐catalyzed anaerobic dehydrogenation, the direct addition of aldehydes was found to be an effective but simpler way of alcohol activation that can lead to efficient and green aldehyde‐catalyzed transition metal‐free dehydrative C‐alkylation of methyl carbinols with alcohols. Mechanistic studies revealed that the reaction proceeds via in situ formation of ketones by Oppenauer oxidation of the methyl carbinols by external aldehydes, aldol condensation, and Meerwein–Ponndorf–Verley (MPV)‐type reduction of α,β‐unsatutated ketones by substrate alcohols, affording the useful long chain alcohols and generating aldehydes and ketones as the by‐products that will be recovered in the next condensation to finish the catalytic cycle. 相似文献
4.
Qing Xu Qiang Li Xiaogang Zhu Jianhui Chen 《Advanced Synthesis \u0026amp; Catalysis》2013,355(1):73-80
In contrast to the borrowing hydrogen‐type N‐alkylation reactions, in which alcohols were activated by transition metal‐catalyzed anaerobic dehydrogenation, the addition of external aldehydes was accidentally found to be a simple and effective protocol for alcohol activation. This interesting finding subsequently led to an efficient and green, practical and scalable aldehyde‐catalyzed transition metal‐free dehydrative N‐alkylation method for a variety of amides, amines, and alcohols. Mechanistic studies revealed that this reaction most possibly proceeds via a simple but interesting transition metal‐free relay race mechanism. 相似文献
5.
Dipankar Srimani Ekambaram Balaraman Boopathy Gnanaprakasam Yehoshoa Ben‐David David Milstein 《Advanced Synthesis \u0026amp; Catalysis》2012,354(13):2403-2406
Cross‐dehydrogenative coupling of primary alcohols with secondary alcohols to obtain mixed esters with the liberation of molecular hydrogen is achieved in high yield and good selectivity under neutral conditions, using a bipyridyl‐based PNN ruthenium(II) pincer catalyst. 相似文献
6.
Wen‐Ting Wei Xu‐Heng Yang Hai‐Bing Li Jin‐Heng Li 《Advanced Synthesis \u0026amp; Catalysis》2015,357(1):59-63
A new transition metal‐free oxidative coupling of unactivated terminal alkenes with aldehydes and hydroperoxides in the presence of 10 mol% potassium tert‐butanolate (t‐BuOK) is described thereby realizing trifunctionalization of alkenes toward 2,3‐epoxy ketones. This method is applicable to a wide range of aldehydes, including aryl and alkyl aldehydes, with excellent functional group tolerance, and provides for the one‐step assembly of 2,3‐epoxy ketones.
7.
Long Wang Daniel L. Priebbenow Liang‐Hua Zou Carsten Bolm 《Advanced Synthesis \u0026amp; Catalysis》2013,355(8):1490-1494
An oxidative cross‐coupling reaction between aldehydes and sulfoximines involving dual C H/N H functionalization has been developed. This reaction process is facilitated by a simple copper catalyst (1 mol% loading) and tert‐butyl hydroperoxide (TBHP) as the oxidant and proceeds under mild reaction conditions to afford a series of valuable N‐acylated sulfoximine derivatives in excellent yields. 相似文献
8.
Yasunari Monguchi Tomohiro Hattori Yasuhiro Miyamoto Takayoshi Yanase Yoshinari Sawama Hironao Sajiki 《Advanced Synthesis \u0026amp; Catalysis》2012,354(13):2561-2567
Simple and efficient protocols for the 10% palladium on carbon (Pd/C)‐catalyzed cross‐coupling reactions between triarylbismuths and aryl halides have been developed. A variety of iodo‐ and bromobenzenes possessing an electron‐withdrawing group on the aromatic nucleus were smoothly cross‐coupled in the presence of 10% Pd/C, sodium phosphate dodecahydrate (Na3PO4⋅12 H2O) and 1,4‐diazabicyclo[2.2.2]octane (DABCO) in heated N‐methyl‐2‐pyrrolidone (NMP) as the solvent. For the arylations of iodobenzenes, the reactions effectively proceeded under the combined use of caesium fluoride (CsF) and 2,2′‐biquinoline. Furthermore, a ligand‐free 10% Pd/C‐catalyzed cross‐coupling reaction between the aryl iodides and triarylbismuths was also established by the addition of tetra‐n‐buthylammonium fluoride trihydrate (TBAF⋅3 H2O) in which the palladium metals were hardly leached from the catalyst into the reaction media. 相似文献
9.
Oxidative homocoupling of aryl‐ and alkenylboronic acids was achieved with Wilkinson’s catalyst. Commercially available 2,2,6,6‐tetramethylpiperidine‐N‐oxyl radical (TEMPO) was used as a stoichiometric oxidant. 相似文献
10.
Silvia Gaspa Andrea Porcheddu Lidia DeLuca 《Advanced Synthesis \u0026amp; Catalysis》2016,358(1):154-158
A novel metal‐free oxidative cross esterification of alcohols has been achieved using trichloroisocyanuric acid as an oxidant. The alcohols were converted in situ into their corresponding acyl chlorides, which were then reacted with primary and secondary aliphatic, benzylic and allylic alcohols and phenols. A wide variety of esters was obtained in satisfactory yields.
11.
Longyang Dian Sisi Wang Daisy Zhang‐Negrerie Yunfei Du 《Advanced Synthesis \u0026amp; Catalysis》2015,357(18):3836-3842
The cross‐coupling reaction between N‐hydroxyphthalimide and various benzylic and allylic hydrocarbons was realized through an organocatalytic radical‐mediated process involving C(sp3) O bond formation using tert‐butyl hydroperoxide (t‐BuOOH) as an oxidant and tetra‐n‐butylammonium iodide [(n‐Bu]4NI] as a catalyst, during which the phthalimide N‐oxyl (PINO) radical and benzylic and allylic radicals were generated in situ and underwent the selective radical/radical cross‐coupling reaction. This novel method provides a convenient metal‐free approach to the synthesis of O‐alkylated hydroxy imides under mild reaction conditions.
12.
Yujiro Hayashi Takahiko Itoh Hayato Ishikawa 《Advanced Synthesis \u0026amp; Catalysis》2013,355(18):3661-3669
A one‐pot transformation of aldehydes into α,β‐unsaturated aldehydes was developed using both N‐benzyl‐N‐methylamine and 2,3‐dichloro‐5,6‐dicyano‐1,4‐benzoquinone (DDQ) as catalysts and MnO2 as a terminal oxidant. An oxidative and enantioselective reaction of aldehydes and nitromethane was established using both diphenylprolinol silyl ether and DDQ as a catalyst with MnO2 as a terminal oxidant, in which synthetically important β‐substituted γ‐nitro aldehydes were obtained with excellent enantioselectivity.
13.
14.
Kazunori Wakasugi Akira Iida Tomonori Misaki Yoshinori Nishii Yoo Tanabe 《Advanced Synthesis \u0026amp; Catalysis》2003,345(11):1209-1214
We have developed an efficient method for the esterification or thioesterification of equimolar amounts of carboxylic acids and alcohols or thiols using a novel reagent, p‐toluenesulfonyl chloride (TsCl) together with N‐methylimidazole. The present method is simple, mild, and reactive, uses readily available and economical reagents. The choice of amine is critical for the present method. The amine, N‐methylimidazole, has two roles: (i) as an HCl scavenger for the initial smooth generation of mixed anhydrides between carboxylic acids and TsCl and (ii) successive formation of highly reactive ammonium intermediates from mixed anhydrides. This method could be applied to various types of carboxylic acids, alcohols, and thiols: a) several functionalities were tolerated; b) two N‐Cbz amino acids were smoothly esterified without racemization; and c) the labile 1β‐methylcarbapenem key intermediate and a pyrethroid insecticide, prallethrin, were successfully prepared. The related amide formation between carboxylic acids and primary or secondary amines was also performed. The proposed reaction mechanism involves a novel method for producing the reactive acylammonium intermediates. The production of these intermediates was rationally supported by a careful 1H NMR monitoring study. 相似文献
15.
A ruthenium‐catalyzed oxidative homo‐coupling reaction of 2‐arylpyridines via C H activation was developed. The reaction could tolerate various functional groups on both the aryl and the pyridyl rings to afford a series of dimerized products with iron(III) chloride (FeCl3) as a stoichiometric oxidant. A tentative mechanism was proposed for this oxidative C H/C H homo‐coupling. 相似文献
16.
Laxmidhar Rout Pinku Nath Tharmalingam Punniyamurthy 《Advanced Synthesis \u0026amp; Catalysis》2007,349(6):846-848
The oxidation of alcohols to aldehydes and ketones has been described using silica‐supported vanadium(IV ) oxide (V/SiO2, 1 ) in the presence of tert‐butyl hydroperoxide in tert‐butyl alcohol at ambient temperature with quantitative yields. The procedure is simple, efficient and environmentally benign. 相似文献
17.
Chaojie Fang Meichao Li Xinquan Hu Weimin Mo Baoxiang Hu Nan Sun Liqun Jin Zhenlu Shen 《Advanced Synthesis \u0026amp; Catalysis》2016,358(7):1157-1163
An efficient method to prepare nitriles from aldehydes using hexamethyldisilazane (HMDS) as the nitrogen source has been developed. The reactions were performed with 2,2,6,6‐tetramethylpiperidine l‐oxyl (TEMPO) as the catalyst, NaNO2 or TBN as the co‐catalyst, and molecular oxygen as the terminal oxidant under mild conditions. A variety of aromatic, heteroaromatic, aliphatic and allylic aldehydes could be converted into their corresponding nitriles in good to excellent yields.
18.
Li Xing Zhoulong Fan Chengyu Hou Guoping Yong Ao Zhang 《Advanced Synthesis \u0026amp; Catalysis》2014,356(5):972-976
An efficient synthetic strategy for the unique class of pyrazolo[1,2‐a]cinnolines was developed through a rhodium‐catalyzed oxidative coupling of N‐aryl‐1H‐pyrazol‐5(4H)‐ones with internal alkynes. This protocol features use of the pyrazolone function in the substrate as an intrinsic directing group, hexafluoroisopropyl alcohol (HFIP) as the solvent, and mild reaction conditions as well as a wide substrate scope.
19.
Nuligonda Thirupathi Surendra Puri Thota Jagadeshwar Reddy Balasubramanian Sridhar Maddi Sridhar Reddy 《Advanced Synthesis \u0026amp; Catalysis》2016,358(2):303-313
Palladium catalyzed conversion of 1‐(2‐aminophenyl)‐propargyl alcohols to 3‐alkynyl quinolines is realized via a cascade that involves aminopalladation, oxidative coupling with alkynes and dehydration. The method is shown to have a broad substrate scope with respect to propargyl alcohols as well as alkynes. Vinyl ketones as coupling partners in the same reaction afforded 3‐alkenyl quinolines with equal ease.
20.
A novel and efficient synthesis of benzoxazole and benzimidazole derivatives via a ligand‐free, copper(I)‐catalyzed, one‐pot cascade process has been developed. A variety of carbodiimides coupled with o‐halophenols or o‐haloanilines to give the products in moderate to excellent yields under the mild conditions. 相似文献