共查询到20条相似文献,搜索用时 375 毫秒
1.
A simple and efficient procedure has been developed for the synthesis of substituted pyrrole-fused isocoumarins from easily available ninhydrin. The cyclic hemiaminal dihydroxy-indenopyrroles, the adducts of ninhydrin with enamines of acetylacetone, give pyrrole-fused isocoumarins upon heating in acidic medium. The process constitutes an interesting acid-catalyzed rearrangement to eight-membered lactams followed by intramolecular cyclization involving the amino and keto groups. 相似文献
2.
Jake R. Zimmerman Brian J. Myers Samantha Bouhall Allison McCarthy Olivia Johntony Madhuri Manpadi 《Tetrahedron letters》2014
In this study, we report a two-step, one pot tandem microwave-assisted reaction of 3-formylchromones with aminopyrazoles followed by a tin-free radical addition. A library of alkyl substituted dihydropyrazolopyrimidines was prepared using this new process. 相似文献
3.
A rapid and efficient method for stereoselective synthesis of new substituted tetrahydro-α-carbolines using Diels-Alder reaction under microwave irradiation has been developed. Further, dehydrogenation of these adducts resulted in synthesis of new substituted α-carbolines. 相似文献
4.
Eun Sun Kim 《Tetrahedron letters》2009,50(36):5098-1390
An efficient synthetic protocol of fully substituted α-pyrones has been developed starting from the Baylis-Hillman adducts. Subsequent Diels-Alder reaction of the α-pyrones and DMAD produced poly-substituted aromatic compounds in high yields. 相似文献
5.
Qiong Zhao 《Tetrahedron》2007,63(27):6296-6305
The Feldman radical oxygenation of vinylcyclopropanes is successfully applied to the synthesis of the highly substituted core of the 1,2-dioxolane natural product, plakortide E. The ratio of the desired cis-1,2-dioxolane can be enhanced by choice of cyclopropane substituents. 相似文献
6.
7.
Francisco Palacios Concepción Alonso Gloria Rubiales Maite Villegas 《Tetrahedron letters》2004,45(21):4031-4034
A method for the preparation of 3-fluoroalkyl substituted 2-aza-butadienes by aza-Wittig reaction of N-vinylic phosphazenes and aldehydes is reported. [4+2] Cycloaddition reaction with enamines affords fluoralkyl substituted pyridine derivatives in a regioselective fashion. 相似文献
8.
A first example of environmentally benign zinc complex catalyzed one-pot four-component reaction between malononitrile, ketone, ammonium acetate and aromatic aldehyde for the facile synthesis of fully substituted pyridines just within 2?min in environmentally friendly solvent ethanol has been optimized. 相似文献
9.
Highly substituted pyridine derivatives have been accessed through an efficient, one-pot, multicomponent reaction of aldehydes, malononitrile, and ammonium acetate in the presence of triethylamine as a catalyst under solvent-free conditions. This procedure affords the desired products in high purity and has advantages such as short reaction time, excellent yields, and simple workup procedure. This procedure affords the desired products in moderate to high yields and has such advantages as short reaction time and simple workup procedure. 相似文献
10.
Substituted 2-bromobenzaldehydes were synthesized from benzaldehydes using a three-step sequence involving a selective palladium-catalyzed ortho-bromination as the key step. O-Methyloxime serves as a directing group in this reaction. A rapid deprotection of substituted 2-bromobenzaldoximes afforded substituted 2-bromobenzaldehydes with good overall yields. 相似文献
11.
Synthesis of the highly substituted polyoxygenated tetrahydropyran ring of botcinic acid, the revised structure of botcinolide is achieved using, as key steps, a highly stereoselective aldol reaction of the titanium enolate from a lactate-derived chiral ketone and a stereoselective dihydroxylation. 相似文献
12.
Jacobi von Wangelin A Neumann H Gördes D Klaus S Jiao H Spannenberg A Krüger T Wendler C Thurow K Stoll N Beller M 《Chemistry (Weinheim an der Bergstrasse, Germany)》2003,9(10):2273-2281
Based upon a highly versatile multicomponent methodology, a new one-pot synthesis of substituted phthalic acid derivatives from alpha,beta-unsaturated aldehydes was developed. The reaction involves the intermediacy of an acetamidodiene species which undergoes Diels-Alder addition to diethyl acetylenedicarboxylate. The resultant acetamidocyclohexadiene is subject to elimination of acetamide under the reaction conditions to give rise to substituted diethyl phthalates in good yields. This domino condensation-cycloaddition-elimination sequence has been applied to a variety of alpha,beta-unsaturated aldehydes. Furthermore, we demonstrated the exploitation of parallelized and automated synthesis technology for the rapid screening of reaction conditions and compositions. Detailed studies revealed the catalytic role of the employed acetamide and the occurrence of a stereoselective 1,4-syn elimination pathway under standard conditions. 相似文献
13.
Srivari Chandrasekhar Vidyavathi Patro Lahu N. Chavan Rambabu Chegondi René Grée 《Tetrahedron letters》2014
An efficient and eco-friendly method for the synthesis of substituted pyrroles has been developed via ruthenium-catalyzed multicomponent reaction of ketone, amine, and ethylene glycol in PEG-400 as solvent medium without using any external ligand. The catalytic system and solvent can be recycled with the same, as well as different, ketones with minimum loss of Ru-catalyst activity. 相似文献
14.
An expedient one-pot sequential five-component synthesis of highly substituted pyrrolidine heterocycles involving [3+2]-cycloaddition of azomethine ylides as the key step is described. The protocol provides a mild reaction condition, high yield of the products, high regioselectivity and operational simplicity to assemble complex structural entity in a single operation. The structure of the product was confirmed by spectroscopic and single crystal X-ray analysis. 相似文献
15.
Toshifumi Miyagawa 《Tetrahedron letters》2007,48(28):4849-4853
Two-step synthesis of 2-aryl-5-(phenylsulfanyl)furans was achieved starting from alkenyl aryl ketones and dichloromethyl phenyl sulfoxide. The phenylsulfanyl group was successfully converted to other functional groups, via sulfinyl group, to give highly substituted 2-arylfurans in good overall yields. 相似文献
16.
Shun-Jun Ji Zhi-Liang Shen Da-Gong Gu Shun-Yi Wang 《Journal of organometallic chemistry》2004,689(10):1843-1848
Michael reactions of deoxybenzoin or dibenzyl ketone with ferrocenyl substituted chalcones catalyzed by sodium hydroxide under ultrasound irradiation can afford the corresponding Michael adducts with excellent yields. It presents a convenient, efficient and simple method for the preparation of ferrocenyl substituted 1,5-diketone compounds in the presence of ultrasound irradiation. In addition, the formation of cyclic, α,β-unsaturated ketones via the reactions of dibenzyl ketone with ferrocenyl substituted chalcones were found, and characterized by X-ray crystal structure analysis. 相似文献
17.
An efficient, one-pot synthesis of substituted pyrazoles from enones, hydrazides, and halides was developed. In comparison with the classical Knorr pyrazole synthesis, this methodology gave a different type of product (R3≥R5). A range of substituted pyrazoles were prepared in good to high yields with complete regioselectivity. 相似文献
18.
Ebrahim Kianmehr Maryam Fardpour Ali Darvish Ali Nemati Kharat Seik Weng Ng 《Tetrahedron letters》2019,60(10):699-702
Synthesis of substituted phthalides through a ruthenium-catalyzed reaction of phthalic anhydrides with acrylates is described. The reaction proceeds via CH bond activation and leads to the formation of vinylated phthalides through a successive double vinylation accompanied by decarboxylation and annulation reactions. 相似文献
19.
The construction of the title compounds has been achieved from properly substituted linear alkynylamides through the suitable combination of two key cyclization steps. First, an intramolecular PIFA-mediated alkyne amidation protocol leads to the creation of the pyrrolidinone nucleus, which under proper manipulation of the generated keto–carbonyl group permits the assembling of the indolizidinone skeleton by the introduction of a subsequent ring closing olefin metathesis step. Finally, its transformation into a series of substituted mono- and trihydroxylated indolizidinone derivatives is achieved by manipulation of the remaining unsaturated fragment under hydrogenation and dihydroxylation conditions. 相似文献
20.
Heng LiuYa-Hui Wang Li-Li ZhuXiao-Xiao Li Wen ZhouZili Chen Wen-Xiang Hu 《Tetrahedron letters》2011,52(23):2990-2993
An efficient and environmentally benign method was developed to synthesize the benzocycles from phenyl substituted allylic acetates through gold catalyzed Friedel-Crafts type carbocyclization reaction. Different substitution patterns were investigated, which gave a series of benzocyclohexane derivatives in moderate to excellent yields. 相似文献