共查询到20条相似文献,搜索用时 15 毫秒
1.
Federico Tutino 《Tetrahedron》2009,65(11):2372-2376
(Z)-Axinohydantoin and (Z)-debromoaxinohydantoin, two pyrrole-imidazole alkaloids isolated from different marine sponges, possess moderate activities in inhibiting the progress of the cell cycle at different phases. A stereoselective synthesis of both natural products was achieved. The key step in the synthetic pathway was the installation of the hydantoin northern ring by using 1-benzoyl-2-methylsulfanyl-1,5-dihydroimidazol-4-one. 相似文献
2.
Sun Joo KimTae Hong Jeon Im Sook MinIn Su Kim Young Hoon Jung 《Tetrahedron letters》2012,53(28):3680-3682
A concise asymmetric total synthesis of (S)-dapoxetine from commercially available 3-chloropropiophenone is described. The key step includes a highly stereoselective amination of chiral benzylic ether, with the retention of stereochemistry, using chlorosulfonyl isocyanate. 相似文献
3.
The stereoselective total synthesis of (+)-(Z)-laureatin is described. The 3,8-dioxabicyclo[5.1.1]nonane skeleton possessing trans-orientated alkyl substituents at the α,α′-positions to the ether linkage was stereoselectively constructed via formation of the oxetane arising from 4-exo cyclization of hydroxy epoxide existing on the oxocene core. 相似文献
4.
In this Communication, we outline a new one-pot, multicomponent coupling reaction that allows easy access to (Z)-trisubstituted allylic alcohols. Our strategy is based on E to Z isomerization of the 1-bromo-1-dialkylvinylborane upon reaction with dialkylzinc reagents, and subsequent transmetalation to give (Z)-trisubstituted vinylzinc species. In situ trapping of the reactive vinylzinc intermediates with aldehydes furnished a series of (Z)-trisubstituted allylic alcohols. This method represents a viable alternative to the Still-Gennari modification of the HWE olefination reaction, and it has the advantage that it allows coupling of larger fragments. 相似文献
5.
François-Hugues PoréeAlexandre Clavel Jean-François Betzer Ange PancraziJanick Ardisson 《Tetrahedron letters》2003,44(40):7553-7556
A (Z)-vinyl (N,N-diisopropyl)carbamate treated with Grignard reagents, under Wenkert Nickel-catalysed conditions, gave access to several substituted (Z)-alkenyl derivatives. These Nickel-catalysed reactions, carried out with vinyl-, phenyl-, p-methoxyphenyl-, trimethylsilylmethylmagnesium bromide and benzylmagnesium chloride, led to the corresponding (Z)-alkenyl derivatives in good yields and high stereoselectivities. 相似文献
6.
The total synthesis of 1-(Z)-atractylodinol, a natural polyacetylenic alcohol with several biological activities, has been achieved using a newly developed telluride synthon and a novel use for the Negishi type coupling reaction employing vinyl tellurides. 相似文献
7.
Claudio C. Silveira Rodrigo Cella Adriano S. Vieira 《Journal of organometallic chemistry》2006,691(26):5861-5866
Alkyne-titanium complexes 3, readily prepared in situ by the reaction of alkynes with Ti(O-i-Pr)4/2 i-PrMgCl, react with electrophilic chalcogen species under mild conditions to provide the corresponding addition products in fair to good yields. The obtained vinylic vic-bis(arylchalcogenides) 4 are useful synthetic intermediates for introducing vinyl functions into organic molecules. 相似文献
8.
Gildas PriéSébastien Richard Jean-Luc ParrainAlain Duchêne Mohamed Abarbri 《Journal of fluorine chemistry》2002,117(1):35-41
(E)- or (Z)-perfluorinated β-enaminoesters were prepared by direct addition of primary or secondary amines to ethyl perfluoroalkynoates without any catalyst. 相似文献
9.
Pd-catalyzed cross-coupling reaction of (E)-bromoenyne 1Z with 1-alkyne and tributylvinyl-stannane occurs with retention of the configuration in benzene but with an inversion of the configuration in DMF or CH2Cl2. On the other hand, that of (Z)-bromoenyne 1E occurs with retention of the configuration in these solvents. 相似文献
10.
Néstor M. Carballeira David Sanabria Norma L. Ayala Clarisa Cruz 《Tetrahedron letters》2004,45(19):3761-3763
A stereoselective synthesis for the (5Z,9Z)-14-methyl-5,9-pentadecadienoic acid and the monounsaturated analog (Z)-14-methyl-9-pentadecenoic acid was accomplished in six to seven steps where double alkyne coupling was the key step. This synthesis will facilitate the study of the topoisomerase I inhibitory profile of this important class of fatty acids. 相似文献
11.
The addition of several trialkyl or triarylindium reagents to the acetates of Baylis-Hillman adducts proceeds readily under the catalysis of copper and palladium derivatives. The reactions of trialkylindiums are catalyzed efficiently by CuI whereas additions of triarylindiums produce better results with Pd(PPh3)4. The reactions with 3-acetoxy-2-methylenealkanoates provide (E)-alkenes, whereas similar reactions with 3-acetoxy-2-methylenealkanenitriles lead to (Z)-alkenes. All the reactions are highly regio- and stereoselective and high yielding. 相似文献
12.
Igor V Ivanov Stepan G RomanovValery P Shevchenko Elena A RozhkovaMikhail A Maslov Nataliya V GrozaNikolai F Myasoedov Hartmut KuhnGalina I Myagkova 《Tetrahedron》2003,59(41):8091-8097
17(R)-OH-AA and 14,15-dehydro-17(R)-OH-AA were synthesized from a common tetraacetylenic precursor and their azide derivatives were obtained in moderate yields via the corresponding p-toluenesulfonates. Since the azido group remained stable during tritiation procedure on Lindlar's catalyst in benzene, both 14,15-dehydro-17(S)-N3-AA and 14,15-dehydro-17(R)-OH-AA constitute useful intermediates in the synthesis of radio-labelled 17(S)-N3-AA and 17(R)-OH-AA. In contrast, reduction of azide in methanol afforded 17(S)-NH2-AA with 95% yield. 相似文献
13.
Kazuhiro Yoshizawa 《Tetrahedron》2007,63(27):6259-6286
Siloxyallenes proved to be a useful functional intermediate in the preparation of (Z)-β-branched Morita-Baylis-Hillman type adducts by the reaction of aldehydes with silylacetylenes or siloxypropynes. Various (Z)-chalcones were stereoselectively synthesized from siloxypropynes via siloxyallenes. 相似文献
14.
12(S),20-DiHETE, prepared by a combination of Evans-Crimmins asymmetric alkylation, Sonogashira alkynylation, and Suzuki-Miyaura cross-coupling, significantly sensitizes phenylephrine-induced vasoconstriction of rat renal interlobar arteries. 相似文献
15.
A simple, novel diastereoselective synthesis of both (E)- and (Z)-allylsilanes via organoboranes is developed. (E)-1-Alkenylboronate esters easily prepared from the corresponding terminal alkynes via hydroboration with dibromoborane-methyl sulfide complex followed by treatment with 1,3-propane diol readily react with trimethylsilylmethyllithium at −78 °C in methanol followed by reaction with iodine in methanol to produce the corresponding (Z)-allylsilanes in high yields (72-80%) and in high stereochemical purities (98% as evidenced by CMR spectral data). Similarly, the (Z)-1-alkenylboronate esters react with trimethylsilylmethyllithium at −78 °C in methanol followed by treatment with iodine in methanol to produce the corresponding (E)-allylsilanes in moderate yields (57-65%) in high stereochemical purities (>98% as revealed by CMR spectral data). 相似文献
16.
The total synthesis of (3Z,6Z,9S,10R)-9,10-epoxy-1,3,6-heneicosatriene, sex pheromone component of Hyphantria cunea, using a convergent synthetic strategy, was achieved through the regioselective coupling of the two fragments, chiral epoxy tosylate and 1,4-diyne. The former fragment was synthesized in two efficient and convenient approaches starting from the same available material using Sharpless AE kinetic resolution as the key step. 相似文献
17.
Subhash P. Chavan Nilesh B. DumareKishor R. Harale Uttam R. Kalkote 《Tetrahedron letters》2011,52(3):404-406
A synthetic route to (2S,3S)-3-hydroxypipecolic acid was achieved from readily available nonchiral pool starting material cis-2-butene-1,4-diol and involved Claisen orthoester rearrangement, Sharpless asymmetric dihydroxylation and intramolecular lactamisation of azido lactone as the key steps. 相似文献
18.
A concise total synthesis of the potent antitumor macrolide (-)-laulimalide is described. The observation that homoallylic (or latent homoallylic) C-O bonds are present at C5, C9, C15, C19, and C23 led to the strategic decision to rely heavily on the asymmetric glycolate alkylation to construct both the C1-C14 fragment 3 and the C15-C27 subunit 4. A diastereoselective addition of a C1-C14 allylstannane to a C15-C27 alpha,beta-epoxyaldehyde served to join the two advanced fragments. A Mitsunobu macrolactonization of hydroxy acid 2 avoided isomerization of the sensitive 2,3-Z-enoate, which has been observed in base-catalyzed macrolactonizations. Removal of two TBS protecting groups to reveal the C15 and C20 hydroxyls occurred without rearrangement to isolaulimalide. 相似文献
19.
A modified Ziegler Ullmann coupling process has been developed as the key step in an effective synthesis of (S)-(−)-N-acetylcolchinol, analogues of which are selective vascular targeting agents with potential importance in cancer chemotherapy. Asymmetric induction is achieved by enamide hydrogenation using FerroTANE catalysts. 相似文献
20.
Hyang Hwa Jeon 《Tetrahedron letters》2007,48(4):627-631
Trifluoromethylated enynyl sulfones 3 were reacted with 2-4 equiv of phenyl, n-hexyl, trimethylsilyl, or triisopropylsilyl substituted ethynyllithium reagents in THF or ether at 0 °C to give trifluoromethylated enediynes 6 (Z)-stereoselectively in 41-96% yields. The reactions of β-fluoro-β-trifluoromethylvinyl sulfone 5 with same ethynyllithium reagents (4 equiv) afforded the corresponding enediynes 6 in 41-90% yields. The cross-coupling reactions of 6 bearing TMS group with aryl iodides in the presence of Pd(PPh3)2Cl2, Ag2CO3, and n-Bu4NBr provided the corresponding enediynes 6 in 20-71% yields. Dimerization of (Z)-6 bearing TMS group in the presence of CuBr2 and K2CO3 yielded dimer (Z,Z)-7 in good yield. 相似文献