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1.
This Letter describes the amination of 3-bromoisoxazoles by a nucleophilic aromatic substitution reaction. We have found 3-bromoisoxazoles to be inert to substitution under thermal conditions, however, the employment of phosphazene bases under microwave irradiation facilitates the amination process and allows the corresponding 3-aminoisoxazoles to be isolated in moderate yield. 相似文献
2.
Carbery DR Reignier S Miller ND Adams H Harrity JP 《The Journal of organic chemistry》2003,68(11):4392-4399
A stereocontrolled approach to alpha-alkyl beta-alkynyl cyclohexanones is reported through a Lewis acid mediated rearrangement reaction of enol ethers bearing an Co-alkyne moiety. The reaction proceeds with high levels of stereoselectivity in the presence of Ti- and B-Lewis acids to provide a range of alpha,beta-disubstituted cyclohexanones in high yield although the products are prone to epimerization at the alpha-position in the presence of the B-promoter system. The potential for an enantioselective variant of this process is outlined, and a rationale for the observed stereochemical trends and detailed structural analyses of the ketone products are described. 相似文献
3.
In this paper we describe the stereoselective synthesis of functionalized lactam 7 via two enantiospecific piperidine-forming techniques and its employment in a general synthetic approach to Nuphar alkaloids. Specifically, the formation of piperidine 18 by formal [3 + 3] cycloaddition and stepwise annelation processes is described; the latter technique was found to be significantly more efficient than the Pd-catalyzed TMM addition process. Finally, exploitation of the exocyclic alkene installed in the piperidine-forming reaction in the transformation of 18 to (-)-deoxynupharidine ((-)-2), (-)-castoramine ((-)-3), and (-)-nupharolutine ((-)-4) via intermediate lactam 7 is delineated. 相似文献
4.
Joseph P. A. Harrity Harry Adams Mark W. Davies Robert A. J. Wybrow Christopher N. Johnson 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(3):o168-o169
A novel [3+2]‐cycloaddition reaction of alkynylboronates and nitrile oxides gave the title compound, C22H32BNO3, as a single regioisomer. The X‐ray crystal structure analysis of this compound shows two independent molecules in the asymmetric unit, each with approximately coplanar isoxazole and boronate rings. 相似文献
5.
Danny Mortimer Matthew Whiting Joseph P.A. Harrity Simon Jones Iain Coldham 《Tetrahedron letters》2014
Lewis acid mediated intramolecular Mannich reaction between an azocinone and a 3-formylindole was investigated as part of a study towards the synthesis of actinophyllic acid. The intramolecular Mannich reaction resulted in a single diastereomer of the 1-azabicyclo[4.2.1]nonan-5-one core framework, although single crystal X-ray structure analysis revealed that this had the undesired stereochemistry in comparison with the natural product. 相似文献
6.
Jiaxin Han Dr. Larry Hoteite Prof. Dr. Joseph P. A. Harrity 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(56):e202201595
The first useful enantioselective Pd-catalyzed asymmetric allylic alkylation of α-fluoro-β-ketoesters has been achieved using the Trost family of chiral ligands yielding products in up to 92 % ee. This work provides new insights regarding the typically modest selectivities associated with acyclic α-fluoroenolates and shows experimental evidence that the typically poor levels of enantiocontrol associated with these systems are not necessarily due to the presence of E/Z enolate mixtures. Finally, this methodology allows the easy preparation of useful 3-fluoropiperidine intermediates, and it is demonstrated that these systems are applicable to a range of functionalization reactions leading to new building blocks for the discovery of bioactive products. 相似文献
7.
Sylvestre P. J. T. Bachollet Dean C. Cocker Harry Adams Prof. Joseph P. A. Harrity 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(40):12889-12893
The aza‐Diels–Alder cycloaddition of 1,2,4‐triazines with alkynes offers a rapid and convenient method for the synthesis of highly substituted pyridines, but often requires harsh conditions and long reaction times. The present study offers a solution to these limitations by use of a temporary tether established by a Lewis acid–base complexation of in situ generated alkynylboranes and triazines bearing a Lewis basic donor. The cycloaddition reactions take place within 20 min at 40 °C and provide direct access to a broad range of pyridines with complete and predictable regiocontrol. The carbon?boron bond can be further functionalised by cross‐coupling allowing further functionality to be introduced after cycloaddition. 相似文献
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9.
[reaction: see text] A stepwise [3+3] annelation sequence to tetrahydropyridines via addition of the Büchi Grignard to aziridines has been developed. These intermediates can be further functionalized with good regio- and stereocontrol and this methodology has been employed in the stereoselective formal synthesis of (-)-dihydropinidine. 相似文献
10.
Brioche JC Goodenough KM Whatrup DJ Harrity JP 《The Journal of organic chemistry》2008,73(5):1946-1953
A stepwise [3 + 3] annelation reaction has been developed that allows access to pyrans from epoxides. This process involves the addition of an allylmagnesium reagent, itself readily prepared from methallyl alcohol, and a Pd-catalyzed cyclodehydration reaction. The potential of this process to be employed in natural product synthesis has been exemplified by its use in the preparation of rhopaloic acid A. 相似文献