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1.
Acetylcyclohexene is transformed into decalones by a two step Michael reaction with high stereo- and regioselectivity, while the Diels - Alder reaction in this case shows poor selectivity. 相似文献
2.
An efficient synthesis of the isoquinuclidone core of xestocyclamine A is described. The key step is a direct aza Diels-Alder reaction of enone 14 and p-anisidine to assemble the isoquinuclidone core of xestocyclamine A. 相似文献
3.
采用W.E.Noland等人提出的咔唑合成路线,以吲哚、醛或酮、丁烯二酰亚胺为原料,在酸催化下经缩合和Diels-Alder反应而形成四氢咔唑。本研究采用乙酸乙酯为溶剂,对甲苯磺酸为催化剂,提高了反应速度和产物质量。共合成11个新的四氢咔唑化合物,进行了^1HNMR和IR测试及元素分析,确认了其结构。 相似文献
4.
Carbodiimides 4, obtained from aza-Wittig reactions of iminophosphorane 3 with aryl isocyanates, reacted with secondary amines in the presence of a catalytic amount of sodium alkoxide to give 1,2,4,5-tetrasubstituted imidazoles 7 in good yields. However, 4-acylimidazoles 11 were obtained, as phenols were used in the presence of a catalytic amount of potassium carbonate due to further air oxidation of the expected products 10. 相似文献
5.
Two chiral guanidines were evaluated as catalysts for the reaction of anthrone (1) with N-methylmaleimide (2). When guanidine 5 was used, the Michael adduct 4 was isolated as a major product. The best enantioselectivity (70% ee) was obtained when the reaction was carried out in THF at - 20℃. 相似文献
6.
Readily recyclable biobased plastics were designed and synthesized utilizing the thermally reversible DA reaction. Furyl-telechelic poly(butylene succinate) prepolymers (PBSF(2)) were extended with bis- and tris-maleimide linkers (M(2) and M(3)) by the DA reaction in the bulk state to produce linear and network polymers, respectively. The DA reaction was able to proceed at 25-80 degrees C, at which crystalline domains of PBSF(2) were present. In the linear polymer system, the molecular weight in the reaction equilibrium was dependent on the chain length of the prepolymer, but almost independent of the reaction temperature. The cycle of DA and retro-DA reactions was repeatable with no prepolymer deterioration. 相似文献
7.
Salakhov M. S. Umaeva V. S. Alikhanova A. I. 《Russian Journal of Applied Chemistry》2009,82(2):323-327
A one-stage synthesis of hinge-ladder polyimides by Diels-Alder poly-condensation of polychlorinated cyclic bisimidodienes with bismaleimides containing aromatic and aliphatic groups was studied.
相似文献8.
Masataka Ihara Masahiro Toyota Keiichiro Fukumoto Tetsuji Kametani 《Tetrahedron letters》1984,25(30):3235-3238
Intramolecular double Michael reaction of the α,β-unsaturated enone ester (16), prepared from the dienone (5), stereoselectively gave the tetracyclic product (17), which was converted into the isoatisirene type compound (20). 相似文献
9.
João P.C. Tomé Dong-Gyu Cho Maria G.P.M.S. Neves Artur M.S. Silva 《Tetrahedron letters》2006,47(18):3131-3134
Sapphyrins participate in Diels-Alder reactions with pentacene affording novel barrelene-fused sapphyrins. The new compounds were synthesized using traditional heating and microwave irradiation conditions. The experiments carried out under microwave irradiation proved cleaner, affording only the monoadduct and in higher yields. 相似文献
10.
11.
Hiroto Nagaoka Kaoru Kobayashi Toshiaki Okamura Yasuji Yamada 《Tetrahedron letters》1987,28(52):6641-6644
The sequential Michael reaction of (S)-4,5-di-O-isopropylidenepent-2- enoate
and
with lithium enolate
afforded diastereo- and enantioselectively bicyclo[2.2.2]octane
and
(or
), respectively. The adducts were efficiently converted into both enantiomeric keto aldehydes (−)-
and (+)-
. 相似文献
12.
Ya. V. Veremeichik P. V. Merabov A. V. Chuiko O. A. Lodochnikova V. V. Plemenkov 《Russian Journal of Organic Chemistry》2013,49(11):1605-1609
From substituted N-sulfinylanilines acting as dienes in the Diels-Alder reaction with norbornadiene S-oxides of benzo-ortho-thiazines were obtained, which were oxidized into the corresponding S,S-dioxides belonging to the class of hybrid thiazinesulfonamide compounds. 相似文献
13.
V. V. Prezhdo A. S. Bykova O. V. Prezhdo Z. Daszkiewicz J. B. Kyziol J. Zaleski 《Russian Journal of General Chemistry》2006,76(1):64-75
Ten mono-, di-, and trinitro derivatives of N-methyl-N-nitroaniline were synthesized and studied by spectral, electrooptical, and quantum-chemical methods. Three of these derivatives, N-methyl-N,2,3-trinitroaniline, N-methyl-N,2,5-trinitroaniline, N-methyl-N,3,5-trinitroaniline, were also examined by the X-ray diffraction method. The N-nitroamino group in their molecules is almost planar, the N7-N8 bond is shortened, and the N8 atom is characterized by a strong deficit of electron density. The dihedral angle between the planes of the N-nitroamino group and the benzene ring is 56°–92°, which makes conjugation between these fragments impossible. The N-nitroamino group in the examined compounds acts as a weak electron donor with respect to the nitro groups in the aromatic ring; the mechanism of this effect is inductive. 相似文献
14.
Branowska D 《Molecules (Basel, Switzerland)》2005,10(1):274-278
Inverse electron demand Diels-Alder reaction of functionalized 5,5'-bi-1,2,4- triazines with bicyclo[2.2.1]hepta-2,5-diene in boiling p-cymene leads to a range of 6,6'- disubstituted-2,2'-bipyridines in good yield. 相似文献
15.
Thiocarbonylchloride reacts with -nitroalcohols yielding symmetrical thionocarbonates. Transesterification of bis(2-fluoro-2,2-dinitroethyl)thioncarbonate affords alkyl 2-fluoro-2,2-dinitroethylthionocarbonates. Fluorination of these thionocarbonates yields the corresponding difluoroformals.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 375–376, February, 1993. 相似文献
16.
Mi Jung Lee 《Tetrahedron letters》2006,47(11):1833-1837
3-Benzylidenecyclohexene derivatives were prepared starting from the Baylis-Hillman adducts by using DBU-promoted domino process involving Michael, aldol, dehydration, and dealkoxycarbonylation. 相似文献
17.
The palladium-catalyzed heteroannulation of N-carbobenzyloxy-o-iodoanilines with 1-phenylthio-1,3-butadiene afforded indolines 7, which were oxidized with DDQ to produce vinylogous 2-(phenylthio)indoles 8. The latter compounds underwent highly regioselective Diels-Alder cycloadditions with methyl propiolate in the presence of MeAlCl(2) or AlCl(3), with simultaneous elimination of benzenethiol, to afford methyl N-(carbobenzyloxy)carbazole-3-carboxylates 9 and, in some cases, the N-deprotected derivatives 11. This is the opposite regiochemistry of that observed previously with the corresponding sulfone analogues of 8. Thus, the regiochemistry of the cycloaddition can be effectively controlled by appropriate choice of oxidation state of the diene sulfur substituent. 相似文献
18.
[reaction: see text] The synthesis of (+)-Sch 642305 (1) has been completed in 17 steps in 1.6% overall yield. Transannular Michael reaction of 2b with NaH in THF provided cyclohexenone 23 stereospecifically. Heating 23 in TFA/CDCl(3) provided a 3:1 equilibrium mixture of 23 and 25, which was hydrolyzed to give (+)-6-epi-Sch 642305 (24) and (+)-Sch 642305 (1), respectively. 相似文献
19.
20.
V. Yu. Nedoshivin A. V. Lyubimov N. L. Zaichenko V. S. Marevtsev M. I. Cherkashin 《Russian Chemical Bulletin》1989,38(11):2363-2366
7-Nitro- and 8-nitroderivatives of 1,3,3-trimethylspiro[indoline-2,3-3H-naphtho[2,1-b][1,4]oxazine] were synthesized, the last of them being prepared by direct nitration. The introduction of the nitro group stabilizes a bipolar colored form, the highest stability being exhibited when the NO2 group is the 8-position.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2576–2580, November, 1989. 相似文献