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1.
Shy-Guey Wang 《Tetrahedron letters》2004,45(32):6183-6185
Diastereoselective allylation of camphorpyrazolidinone derived α-ketoamides was examined using allyltributyltin in the presence of various Lewis acids. The corresponding optically enriched quarternary α-hydroxy carbonyls were obtained in reasonable to excellent material yields (51-95%) and with practical levels of stereoselectivity (up to >95% de) when a stoichiometric amount of Sn(OTf)2 was used. The stereochemical induction is discussed. 相似文献
2.
Syun-ichi Kiyooka Hiroko Sasaoka Ryoji Fujiyama Clayton H. Heathcock 《Tetrahedron letters》1984,25(46):5331-5334
1,3-Syn diastereofacial selectivity (2.8 : 1) has been found in the titanium tetrachloride — titanium tetra-isopropoxide mediated reaction of allylsilane with β-alkoxy acetal 2. 相似文献
3.
Neelesh A. Kulkarni 《Tetrahedron letters》2006,47(4):611-613
The nucleophilic allylation of camphor derived glyoxylic oxime ethers was carried out using allyltributyltin in the presence of Sn(OTf)2 affording the corresponding homoallylic amines in high chemical yields (up to 94%) and excellent stereoselectivities (up to >99%). 相似文献
4.
Thiosalicylic acid reacts with 1,4-benzoquinone to give 2-(1,4-dihydroxyphenylsulfanyl)benzoic acid which undergoes intramolecular
cyclization to 1,4-dihydroxythioxanthen-9-one in the presence of dehydrating agents. Cyclization of arylsulfanylbenzoic acids
obtained by reaction of thiosalicylic acid with 1,4-naphtho- and anthraquinones leads to 1,4-quinone derivatives, benzo- and
naphthothioxanthenetriones. 相似文献
5.
A new direct allylation of the aromatic compound has been developed. A combination of allylsilane, allylgermane, or allylstannane and thallium (III) trifluoroacetate gave rise to an allyl cationic species which was allowed to react with an aromatic compound, a nucleophile, to give allylation product(s) in good yields. 相似文献
6.
The advent of chiral Lewis base-promoted allylation of aldehydes has opened a new direction in the catalytic enantioselective construction of homoallylic alcohols. This short review outlines the conceptual framework for the creation of this new process and the interplay of mechanistic investigations and synthetic studies that have conspired to produce a useful new reaction. The current state-of-the-art in catalyst design and application of the reaction in synthesis are briefly illustrated. 相似文献
7.
Photochemical reactions between 1,4-benzo- and 1,4-naphthoquinone and several heteroaromatic carbaldehydes were investigated under solar irradiation conditions. These reactions gave the corresponding heteroacylated hydroquinones in the range 71%-92% yield. 相似文献
8.
Exposure of 3α-chloro-3-phenylthioazetidin-2-ones and allyltrimethylsilane to a Lewis acid promotes a remarkably facile and stereoselective C-3 allylation to give 3α-allyl-3-phenylthioazetidin-2-ones 4 in excellent yield. These allylated azetidin-2-ones undergo smooth desulphurization with tri-n-butyltin hydride or Raney-nickel producing cis-3-allyl- and cis-3-propylazetidin-2-ones. 相似文献
9.
10.
2-Phosphonoacrylates containing four chiral alcohol auxiliaries were efficiently prepared and evaluated in Lewis acid mediated Diels–Alder reactions. Under the activation of SnCl4, all reactions performed in CH2Cl2 at ?65 °C exclusively afforded the endo (endo-to-carboxylate) cycloadducts with dr’s ranging from 50:50 to >99:1. The best facial selectivity was obtained from the substrate bearing a (?)-phenylmenthyl group, to give adducts as (dr >99:1) or almost as (dr = 99:1) single diastereomers. Detailed strategies for the structural elucidation of the cycloadducts as well as a rationalization of the observed stereoselectivity are described. 相似文献
11.
Patient L Berry MB Coles SJ Hursthouse MB Kilburn JD 《Chemical communications (Cambridge, England)》2003,(20):2552-2553
Silylated methylenecyclopropyl hydrazones on treatment with BF3 x Et2O cyclise to give heterocyclic products involving a novel sequence of hydride and silyl shifts via a series of increasingly stable cationic intermediates. 相似文献
12.
The direct activation of C-O bonds in 2-butene-1,4-diol by palladium complexes has been accelerated by carrying out the reactions in the presence of a titanium reagent. Palladium-catalyzed regiospecific tandem allylation of 2-aminophenols with 2-butene-1,4-diol leads to 3,4-dihydro-2-vinyl-2H-1,4-benzoxazines. 相似文献
13.
《Comptes Rendus Chimie》2014,17(6):563-569
A series of 1,4-benzoquinone derivatives from 2,5-dichloro-3,6-diethoxy-1,4-benzoquinone and 2,6-dichloro-3,5-diethoxy-1,4-benzoquinone were prepared by nucleophilic substitution reactions of sulfur and nitrogen nucleophiles. Spectral techniques (1H NMR, 13C NMR, FT–IR, and LC–MS) were employed to structurally characterize the reaction products of alkoxy, chloro substituted-1,4-benzoquinones with thiols and amines in the presence of sodium carbonate in ethanol at room temperature. The orientations and the regioselectivity of the reactions of alkoxy, chloro substituted-1,4-benzoquinones with various thiol and amine nucleophiles are discussed. 相似文献
14.
Ayecik KAMAZ 《Turkish Journal of Chemistry》2021,45(2):475
A series of NH-substituted-1,4-quinones, possessing one, two, three or not chlorine, were synthesized by the reaction between different quinones (p-chloranil (1), p-toluquinone (2), or 2,3-dichloro-1,4-naphthoquinone (3)) and (-)-cis-myrtanylamine (5) via nucleophilic reactions. Moreover, 2-bromo-1,4-naphthoquinone (4) was reacted with 2-(methylthio)ethylamine (11) to produce amino-substituted naphthoquinones (12 and 13), bearing with bromine and not bromine. In addition, 2-bromo-1,4-naphthoquinone (4) was reacted with 4′-aminodibenzo-18-crown-6 (14) and 4′-aminobenzo-18-crown-6 (16) to yield crown-containing 1,4-naphthoquinones (15 and 17), respectively. New compounds were characterized, providing 1H NMR, 13C NMR, FTIR, MS-ESI, UV/Vis and elemental analysis. 相似文献
15.
《Tetrahedron: Asymmetry》1998,9(15):2693-2699
The first catalytic enantioselective Torgov cyclisation has been achieved in 72% yield and up to 70% ee by using a chirally modified Ti complex. The new bis-steroidal ligands were found to be clearly superior to BINOL. 相似文献
16.
R. T. Pardasani P. Pardasani S. Muktawat R. Ghosh T. Mukherjee 《Research on Chemical Intermediates》1998,24(9):973-978
While pursuing our studies on the synthesis of anthracyclinones and heteroanthracyclinones. We have studied the photocyclisation
of benzoyl-1,4-benzoquinones leading to xanthones and phenyl gentisate esters. To the best of our knowledge this is the first
observation of photo-xanthone synthesis. Some mechanistic aspects of the reaction have been presented. 相似文献
17.
The activation of C-O bonds in cis-1,4-diacetoxy-2-butene has been accelerated by carrying out the reactions in the presence of palladium complexes associated with ligands. Palladium-catalyzed tandem allylation of 1,2-phenylenediamines with cis-1,4-diacetoxy-2-butene leads to 1,2,3,4-tetrahydro-2-vinylquinoxalines in good yields. 相似文献
18.
[reaction: see text] Lewis acid-promoted addition of allyltri-n-butylstannane to o-quinonediimines afforded tetrahydroquinoxaline derivatives or allylated amides depending on the nature of the substituent on imine nitrogen. 相似文献
19.
In the presence of BF3·.OEt2, aryl dienyl ethers were rearranged under mild conditions to afford dienyl phenols in good yields. 相似文献
20.
Singh AP Roesky HW Carl E Stalke D Demers JP Lange A 《Journal of the American Chemical Society》2012,134(10):4998-5003
Cationic and anionic species of heavier low-valent group 14 elements are intriguing targets in main group chemistry due to their synthetic potential and industrial applications. In the present study, we describe the synthesis of cationic (MCl(+)) and anionic (MCl(3)(-)) species of heavier low-valent group 14 elements of germanium(II) and tin(II) by using the substituted Schiff base 2,6-diacetylpyridinebis(2,6-diisopropylanil) as Lewis base (LB). Treatment of LB with 2 equiv of GeCl(2)·dioxane and SnCl(2) in toluene gives compounds [(LB)Ge(II)Cl](+)[Ge(II)Cl(3)](-) (1) and [(LB)Sn(II)Cl](+)[Sn(II)Cl(3)](-) (2), respectively, which possess each a low-valent cation and an anion. Compounds 1 and 2 are well characterized with various spectroscopic methods and single crystal X-ray structural analysis. 相似文献