Useful four-carbon synthons en route to monastrol analogs
作者:Amr M. Abdou、S. Botros、Rasha A. Hassan、Mona M. Kamel、Douglass F. Taber、Azza T. Taher
DOI:10.1016/j.tet.2014.11.022
日期:2015.1
A simple protocol has been established for the preparation of a family of crystalline N-aryl γ-hydroxycrotonamides, useful four-carbon synthons. These were further elaborated to analogs of monastrol having variant ester sidechains, that were evaluated for their anticancer activity employing the NCI 60 cell line panel.
We have presented the first palladium(II)‐thiadiazole‐ligand catalytic system, employing 1,3,4‐thiadiazole derivative as ligand to achieve the esterification of terminal olefin with excellent regio‐ and stereoselectivity. This work is significant in that it represented the first application of 1,3,4‐thiadiazole in organic synthesis. Furthermore, it was also featured by its satisfied yields, mild reaction
1,3-Dipolar Cycloaddition Reaction of Nitrile Oxides Revisited-Unusual Side Products Characterized by 2D NMR
作者:M. Gucma、W. M. Gołębiewski
DOI:10.1002/jhet.1792
日期:2014.5
Cycloaddition of (4‐trifluoromethyl)phenylnitrile oxide to N‐(4‐methoxyphenyl)acrylamide afforded bicyclic tetrahydro‐oxazolo‐(3,2‐b)[1,3]oxazine‐2‐carboxamide derivative in result of N‐acylation of the initially formed cycloadduct by the dipolarophile. 2:1 Cycloaddition of the same dipole to N‐(4‐methoxyphenyl)crotonamide yielded dihydro[1,2]‐oxazolo[2,3‐d][1,2,4]oxadiazole‐7‐carboxamide because of
(4-三氟甲基)苯腈氧化物与N-(4-甲氧基苯基)丙烯酰胺的环加成反应可得到双环四氢-恶唑并(3,2- b)[1,3]恶嗪-2-羧酰胺衍生物,这是由于N-酰化了最初由双极性亲和剂形成环加合物。2:1将同一偶极环加成至N-(4-甲氧基苯基)巴豆酰胺可产生二氢[1,2]-恶唑并[2,3- d ] [1,2,4]恶二唑-7-羧酰胺,因为第二次加成偶极与第一个形成的2-异恶唑啉化合物的C═N键的关系。产品的结构已通过1D和2D NMR光谱的广泛应用得以阐明。
Synthesis of Trifluoromethylated Isoxazolidines: 1,3-Dipolar Cycloaddition of Nitrosoarenes, (Trifluoromethyl)diazomethane, and Alkenes
作者:Gary A. Molander、Livia N. Cavalcanti
DOI:10.1021/ol401402d
日期:2013.6.21
literature that provide trifluoromethylated versions of these compounds have prompted us to investigate a 1,3-dipolarcycloaddition route providing access to N-functionalized isoxazolidines containing a trifluoromethyl group. Thus, a 1,3-dipolarcycloaddition of nitrosoarenes, (trifluoromethyl)diazomethane, and alkenes was developed. The starting materials can be synthesized from easy to handle and accessible
Stereoselective synthesis of .beta.-lactams by oxidative coupling of dianions of acyclic tertiary amides
作者:Takeo Kawabata、Tatsuya Minami、Tamejiro Hiyama
DOI:10.1021/jo00032a047
日期:1992.3
Tertiary amides RCH2CON(R')CH2Z, where Z is an electron-withdrawing group, were converted into dianions by treatment with 2 equiv of n-butyllithium or tert-butyllithium, and the dianions were oxidized with N-iodosuccinimide (NIS) or a Cu(II) carboxylate to form beta-lactams stereoselectively. The stereochemistry of beta-lactam formation depends on the oxidant; NIS is cis-selective, whereas Cu(II) is nonselective or slightly trans-selective. A high degree of asymmetric induction in the formation of beta-lactams was achieved by using (R)-1-phenylethylamine as a chiral auxiliary. This asymmetric ring closure was applied to the preparation of cis-beta-lactam 31, an intermediate for the synthesis of the monobactam antibiotic carumonam.