6191-71-5Relevant academic research and scientific papers
Access to Saturated Thiocyano-Containing Azaheterocycles via Selenide-Catalyzed Regio-A nd Stereoselective Thiocyanoaminocyclization of Alkenes
Wei, Wei,Liao, Lihao,Qin, Tian,Zhao, Xiaodan
, p. 7846 - 7850 (2019/10/10)
An efficient route for the synthesis of saturated thiocyano-containing azaheterocycles by selenide-catalyzed regio-A nd stereoselective thiocyanoaminocyclization of alkenes is disclosed. The desired products were obtained in moderate to high yields under mild conditions. The generality of this method was elucidated by its efficient application in thiocyano oxycyclization of alkenes.
Synthesis method of aggregation pheromone (E)-cis-6, 7-epoxy-2-nonenal of Aromia bungii
-
Paragraph 0041; 0042; 0043; 0044; 0045, (2019/05/08)
The invention relates to a synthesis method of aggregation pheromone (E)-cis-6, 7-epoxy-2-nonenal of Aromia bungii, which belongs to the field of pharmaceutical synthesis. The synthesis method comprises the following steps: taking 1, 4-butanediol as a raw material, singly protecting diol with DHP (dihexylphthalate) and then oxidizing TEMPO (tetramethylpiperidine oxide) into 4-((tetrahydro-2H-pyran-2-base) oxy) butyraldehyde; performing a Wittig reaction, so as to obtain (Z)-2-(hepta-4- alkene-1-base-oxy) tetrahydro-2H-pyran; removing the protection of the DHP and oxidizing TEMPO, so as to obtain (Z)-4-heptenal; performing a Wittig reaction, so as to obtain (2E, 6Z)-nona-2, 6-heptadienal; finally, performing epoxidation, so as to obtain the aggregation pheromone (E)-cis-6, 7-epoxy-2-nonenalof the Aromia bungii. The total yield is 6.5%. In the synthesis method, the 1, 4-butanediol with low cost is taken as the starting raw material; the synthesis method has the advantages of being simple in operation and mild in conditions, therefore, the synthesis method is suitable for large-scale preparation.
Cleavage of benzyl ethers by triphenylphosphine hydrobromide
Ramanathan, Mani,Hou, Duen-Ren
experimental part, p. 6143 - 6145 (2010/12/24)
Triphenylphosphine hydrobromide was found to cleave the benzyl ethers derived from 1°, 2° alkyl, and aryl alcohols to the corresponding alcohols and benzyltriphenylphosphonium bromide in good yields. Alkene and allyl phosphonium salts were produced from the benzyl ethers with 3° alkyl and allyl groups, respectively. These results indicate that the formation of the product is determined by the relative stability of the carbocationic intermediate. The anhydrous, stoichiometric amount of PPh3·HBr offers a new and effective method for the deprotection of benzyl ethers.
New modes for the osmium-catalyzed oxidative cyclization
Donohoe, Timothy J.,Lindsay-Scott, Peter J.,Parker, Jeremy S.,Callens, Cedric K. A.
supporting information; experimental part, p. 1060 - 1063 (2010/06/13)
(Figure Presented) The osmium-catalyzed oxidative cyclization of amino alcohol initiators formally derived from 1,4-dienes Is an effective method for the construction of pyrrolidines, utilizing a novel reoxidant (4-nltropyridlne N-oxide = NPNO). The cyclization of enantlopure syn- and anti-amino alcohols gives rise to enantlopure cis- and frans-2,5-disubstituted pyrrolidines, respectively. Moreover, the cyclization of Ws-homoallylic amines bearing an exocyclic chelating group Is shown to be a complementary method for irans-pyrrolidine formation.
Asymmetric iodocyclization catalyzed by salen-CrIIICl: Its synthetic application to swainsonine
Kwon, Hyo Young,Park, Chul Min,Lee, Sung Bae,Youn, Joo-Hack,Kang, Sung Ho
, p. 1023 - 1028 (2008/09/21)
The previously developed enantioselective iodocyclization of γ-hydroxy-cis-alkenes required 30 mol% of (R,R)-salen-CoII complex as chiral catalyst and 0.75 equivalent of N-chlorosuccinimide (NCS) as activator to produce 2-substituted tetrahydrofurans with 61 to 90% ee. Due to the considerable loading amount of the CoII complex, another more effective catalyst was pursued by screening (R,R)-salentransition metal complexes. When 10 mol % of the catalysts were applied with 0.5 equivalent of NCS, a higher level of stereoselectivity was attained with the corresponding CrIIICl (84% ee), MnIICl (52% ee) and CoII complexes (66% ee). Refinement of the conditions established a novel catalytic enantioselective iodocyclization protocol using iodine in the presence of 7 mol% of (R,R)-salen-CrIIICl complex activated by 0.7 equivalent of NCS in toluene to induce 74 to 93 % ee.
Reaction of alkene-zirconocene complexes and cyclic enol ethers through new reaction pathways
Barluenga, Jose,Alvarez-Rodrigo, Lucia,Rodriguez, Felix,Fananas, Francisco J.
, p. 3932 - 3935 (2007/10/03)
Unexpected results are obtained on treatment of alkene-zirconocene complexes with cyclic enol ethers. The ring size of the enol ether makes the reaction proceed through different mechanisms allowing Zalkenols to be prepared from furan derivatives and cycl
A study of 1,5-hydrogen shift and cyclization reactions of an alkali isomerized methyl linolenoate
Matikainen, Jorma,Kaltia, Seppo,Ala-Peijari, Maija,Petit-Gras, Ninna,Harju, Kirsi,Heikkil?, Jaakko,Yksj?rvi, Raija,Hase, Tapio
, p. 567 - 573 (2007/10/03)
Heating a mixture formed by alkali isomerization of methyl linolenoate (1) produces a complex mixture with the bicyclic hexahydroindenoic esters 4β-(7-methoxycarbonylheptyl)-5α-methyl-2,3,3aα,4,5, 7aαhexahydroindene (CL5) and 4β-ethyl-5α-(6-methoxycarbonylhexyl)-2,3,3aα,4,5, 7aα-hexahydroindene (CL6) as main components. Similar isomerization reactions of three synthetic model compounds, methyl 9Z,13E,15Z-octadecatrienoate (2), 9Z,14E,16E-octadecatrienoate (4) and 9Z,11E,15Z-octadecatrienoate (5) corroborated the results obtained with alkali isomerized methyl linolenoate.
Stereoselective Synthesis of Alcohols containing (Z)- and (E)-Olefins, Dienes, Enynes and Styrenes: Cyclic β-Halogeno Scissions using Samarium Diiodide as the Electron-transfer Agent
Crombie, Leslie,Rainbow, Linda J.
, p. 673 - 688 (2007/10/02)
In contrast to the sodium-mediated ring scission of 2-substituted 3-chloro ethers of the tetrahydrofuran series, samarium diiodide gives olefins of high (E)-stereoselectivity and provides (E)-conjugated and unconjugated dienes, styrenes and enynes in good yield without appreciable over-reduction.Whilst the SmI2 scission of 3-chloro-2-alkyltetrahydropyrans gives (Z)-rich (Z)/(E) olefin mixtures, the 2-(alk-1'-ynyl) members give (Z)-enyne alkohols with high stereoselectivity, providing a valuable complement to the (E)-enyne synthesis employing the tetrahydrofuran series.In electron-transfer scissions using sodium, the stereochemistry of the product alcohols is related to the ground-state conformation of the cis- and trans-pyrans and -furans.The slow SmI2-mediated reactions appear to involve samarium-complexed intermediates having structures independent of the original conformation, or of the cis- or trans-geometry of the furan or pyran, and it is the transition states from these intermediates that determine the stereochemical outcome.Scissions in the tetrahydrofuran series can be accelerated by addition of HMPA or DMPU with only a little deterioration in stereoselectivity, but in the tetrahydropyran series there are drastic changes in product stereochemistry when DMPU is added.Brief comment is made on the synthesis of tetrahydro-furan and pyran precursors.
Xanthate Transfer Cyclization of Glycolic Acid-Derived Radicals. Synthesis of Five- to Eight-Membered Ring Ethers
Udding, Jan H.,Giesselink, J. P. M.,Hiemstra, Henk,Speckamp, W. Nico
, p. 6671 - 6682 (2007/10/02)
A novel method for the preparation of functionalized five- to eight-membered ring ethers is described.This method involves the xanthate transfer radical cyclization of 2-(alken-1-oxy)-2-acetic acid methyl esters 6 to give good yields of xanthate-substituted five- to eight-membered ethers 7 and/or 8, depending on the length of the carbon chain.These cyclic ethers are usually obtained as mixtures of diastereomers.The cyclizations are performed at 150-160 deg C in tert-butylbenzene with di-tert-butyl peroxide as the initiator.This group-transfer radical cyclization was successfully applied in a total synthesis of lauthisan (44).The use of benzoyl xanthate (56) as a catalyst allows a visible light-induced xanthate transfer cyclization to a tetrahydrofuran in high yield.
