共查询到20条相似文献,搜索用时 15 毫秒
1.
Ochiai M Nishi Y Goto S Shiro M Frohn HJ 《Journal of the American Chemical Society》2003,125(50):15304-15305
Reported here for the first time are the synthesis, structure, and reaction of hypervalent 1-alkynyl(aryl)-lambda3-bromanes. BF3-catalyzed ligand exchange on bromine(III) of p-trifluoromethylphenyl(difluoro)-lambda3-bromane with 1-alkynyl(trimethyl)stannanes in dichloromethane at -78 degrees C afforded 1-alkynyl(aryl)-lambda3-bromanes in good yields. Trimethyl(trimethylsilylethynyl)stannane gave silylethynyl-lambda3-bromane selectively. 13C NMR chemical shifts of acetylenic carbon atoms of alkynylbromanes are compared with those of alkynyl-lambda3-iodanes and explained in terms of the spin-orbit-induced heavy atom effects. The structure of tert-butylethynylbromane was established by a single-crystal X-ray analysis of its crown ether complex. The 1-alkynyl(aryl)-lambda3-bromanes serve as highly electron-deficient Michael acceptors and undergo tandem Michael-carbene rearrangements by the reaction with sulfonate anions, yielding 1-alkynyl sulfonates. 相似文献
2.
Exposure of 1-alkynyl[p-(trifluoromethyl)phenyl](tetrafluoroborato)-lambda(3)-bromanes to sodium benzenesulfinate or sodium trifluoromethanesulfinate in dichloromethane at 0 degree C under argon resulted in tandem Michael-carbene insertion reactions to produce 1-sulfonylcyclopentenes selectively, with concomitant formation of a small amount of rearranged 1-alkynyl sulfones. 相似文献
3.
Exposure of 1-alkynyl[p-(trifluoromethyl)phenyl](tetrafluoroborato)-lambda3-bromanes to 2-mercaptobenzimidazole or benzothiazole in dichloromethane at 0 degrees C under argon resulted in a domino Michael addition-carbene rearrangement-cyclization reaction to produce directly tricyclic heterocycles in high yields, whereas the reaction with 2-mercaptobenzoxazole afforded 1-alkynyl sulfides. 相似文献
4.
Exposure of 1-alkenyl(phenyl)- and 1-alkynyl(phenyl)-λ3-iodanes to THF at room temperature in the presence of a catalytic amount of trialkylborane results in smooth reduction to give 1-iodo-1-alkenes and 1-iodo-1-alkynes as major products, respectively. The key step in the reductions probably involves a single-electron transfer from α-tetrahydrofuryl radical to the λ3-iodanes, which generates the labile [9-I-2] iodanyl radicals. 相似文献
5.
[reaction: see text]. Exposure of (E)-beta-alkylvinyl(phenyl)-lambda3-iodanes to thioamides in dichloromethane at room temperature was found to result in a bimolecular nucleophilic substitution (S(N)2) at the vinylic carbon atom to give inverted (Z)-enethiols and/or (Z)-S-vinylthioimidonium salts. Vinylic S(N)2 reactions with thioureas are also discussed. 相似文献
6.
An efficient method for generation of alpha-lambda3-iodanyl ketones from (Z)-(2-acetoxyvinyl)(phenyl)-lambda3-iodanes was developed. The method involves ester exchange of (Z)-2-acetoxyvinyl-lambda3-iodanes with methanol in the presence of triethylamine. alpha-lambda3-Iodanyl ketones react with a variety of nucleophiles such as halides, thiols, phosphines, phosphinic acids, and phosphates, under the conditions which produce alpha-functionalized carbonyl compounds probably via an S(N)2 pathway. 相似文献
7.
Ochiai M Suefuji T Miyamoto K Shiro M 《Chemical communications (Cambridge, England)》2003,(12):1438-1439
The single crystal X-ray structure of the supramolecular complex formed between diphenyl-lambda3-iodane (Ph2IBF4) or 1-alkynyl(phenyl)-lambda3-iodane [Bu(t)CCI(Ph)BF4] and 1,10-phenanthroline indicates a hitherto unknown distorted trigonal bipyramidal geometry around iodine(III), in which 1,10-phenanthroline acts as a bidentate ligand and occupies equatorial sites. 相似文献
8.
Masahito Ochiai Kazunori MiyamotoTakashi Suefuji Motoo ShiroShigeru Sakamoto Kentaro Yamaguchi 《Tetrahedron》2003,59(51):10153-10158
Slow evaporation of a solution of 1-decynyl(phenyl)(tetrafluoroborato)-λ3-iodane and 18-crown-6 in dichloromethane-diethyl ether-hexane gave a supramolecular 1:1 complex, while 3,3-dimethyl-1-butynyl- and phenylethynyl(phenyl)(tetrafluoroborato)-λ3-iodanes afforded 2:1 complexes. Complexation with 18-crown-6 increased the thermal stability of the phenylethynyl-λ3-iodane. Solid state and solution structures of these complexes were examined by single crystal X-ray analyses, 1H and 13C NMR spectra, and cold-spray ionization MS. Binding constants were measured by 1H NMR titrations. 相似文献
9.
Highly substituted indenes have been prepared in good yields by the palladium-catalyzed carboannulation of diethyl 2-(2-(1-alkynyl)phenyl)malonate with aryl, benzylic, and alkenyl halides. The reaction conditions and the scope of the process were examined, and a possible mechanism is proposed. 相似文献
10.
[reaction: see text] The palladium-catalyzed reaction of readily accessible diethyl 2-(2-(1-alkynyl)phenyl)malonates with aryl halides under a balloon pressure of CO produced 2-substitued 3-aroylindenes in good yields. The reaction is believed to proceed via cyclization of the alkyne containing a proximate nucleophilic center promoted by an acylpalladium complex. 相似文献
11.
By using carbophilic Lewis acids, In(OTf)3, NiCl2, and AuCl(PPh3)/AgNTf2, a concise and efficient synthesis of 1,3-disubstituted 1,2-dihydroisoquinolines has been achieved via tandem nucleophilic addition and cyclization of 2-(1-alkynyl)arylaldimines. Addition of proton sources such as water, CF3CH2OH, and 2,6-di-tert-butyl-4-methoxyphenol was essential for the Lewis acid-catalyzed tandem reactions with organometallic reagents. By switching these catalysts, various types of nucleophiles such as allylstannanes, silyl enol ethers, alkenylboronic acids, and active methylene compounds could be introduced at the C1 position of 1,2-dihydroisoquinolines in this transformation. Furthermore, this method proved to be applicable to the synthesis of 1H-isochromene derivatives via the same tandem reaction of 2-(1-alkynyl)arylaldehydes. 相似文献
12.
4-(1-Alkynyl)-3-bromo- and 4-(1-alkynyl)-3-chloro-2(5H)-furanones have been regioselectively synthesized in moderate to good yields by a new version of the Pd/Cu-catalyzed Sonogashira reaction involving treatment of 1-alkynes with 3,4-dibromo- and 3,4-dichloro-2(5H)-furanone, respectively, in the presence of KF as a base. 4-(1-Alkynyl)-3-bromo-2(5H)-furanones have been found to be able to undergo Stille-type and Suzuki-type reactions with aryl(tributyl)tins and arylboronic acids, respectively, to give 4-(1-alkynyl)-3-aryl-2(5H)-furanones in modest to satisfactory yields. Some 4-(1-alkynyl)-substituted 2(5H)-furanones so prepared have been found to exhibit significant cytotoxic activities, especially against human leukemia cell lines. 相似文献
13.
Ochiai M Takeuchi Y Katayama T Sueda T Miyamoto K 《Journal of the American Chemical Society》2005,127(35):12244-12245
Reported here for the first time is the iodobenzene-catalyzed alpha-oxidation of ketones, in which diacyloxy(phenyl)-lambda3-iodanes generated in situ act as real oxidants of ketones and m-chloroperbenzoic acid serves as a terminal oxidant. Oxidation of a ketone with m-chloroperbenzoic acid in acetic acid in the presence of a catalytic amount of iodobenzene, BF3.Et2O, and water at room temperature under argon affords an alpha-acetoxy ketone in good yield. p-Methyl- and p-chloroiodobenzene also serve as efficient catalysts in this direct oxidation. We found that when the reaction was carried out in the absence of a catalytic amount of iodobenzene, Baeyer-Villiger oxidation of a ketone took place. It is noted that use of water and BF3.Et2O is crucial to the success of this alpha-acetoxylation. 相似文献
14.
A series of 4-halophosphaisocoumarins were prepared with high regioselectivity in good to excellent yields under mild conditions by the reaction of 2-(1-alkynyl)phenylphosphonic acid diesters with I2 in CHCl3 or ICl in CH2Cl2, or by the reaction of 2-(1-alkynyl)phenylphosphonic acid monoesters with NBS or NCS in DMF. Whether the alkynylphosphonates could cyclize or not was affected by the substituents, reaction solvents and electrophiles. A rationale for this reaction is discussed. 相似文献
15.
The potent dehydrating ability of difluoro(aryl)-lambda (3)-iodanes is exploited to develop a convenient (19)F-NMR-based aquametry method that is more sensitive than coulometric Karl Fischer titration. The key difluoro(aryl)-lambda (3)-iodane reagents are synthesized readily from commercially available and inexpensive precursors. 相似文献
16.
The palladium-catalyzed cross-coupling of aryl halides or vinylic halides or triflates and 1-(1-alkynyl)cyclobutanols affords good yields of stereoisomerically pure 2-arylidene- or 2-(2-alkenylidene)cyclopentanones, respectively. The process involves (1) oxidative addition of the organic halide or triflate to Pd(0), (2) regioselective, intermolecular carbopalladation of the carbon-carbon triple bond of the 1-(1-alkynyl)cyclobutanol to produce a vinylic palladium intermediate, (3) regioselective ring expansion to a palladacycle, and (4) reductive elimination of the 2-alkylidenecyclopentanone with simultaneous regeneration of the Pd(0) catalyst. Generally, the best results are obtained by employing 10 mol % of Pd(OAc)(2), 20 mol % of PPh(3), 2 equiv of the aryl or vinylic iodide or vinylic triflate, 2 equiv of diisopropylethylamine, and n-Bu(4)NCl in DMF as the solvent. 相似文献
17.
Barange DK Nishad TC Swamy NK Bandameedi V Kumar D Sreekanth BR Vyas K Pal M 《The Journal of organic chemistry》2007,72(22):8547-8550
Herein, we report transition metal-catalyzed intramolecular cyclization of o-(1-alkynyl)benzenesulfonamides to afford 3-substituted benzothiazines regioselectively via a C-N bond forming reaction and Cu-catalyzed sequential C-N and C-C bond formation leading to the corresponding 3,4-disubstituted derivatives. 相似文献
18.
A homo-Michael addition reaction of lithium selenolates with 1-(1-alkynyl)cyclopropyl ketones and the subsequent reaction with electrophiles such as PhSeBr, NFSI and NCS is reported. Based on the nature of electrophiles, this reaction may afford highly substituted 1,2-allenyl ketones or furans (E(+) = PhSe(+)) and 2-alkynyl ketones (E(+) = F(+), Cl(+), active halides) as the final products, respectively. 相似文献
19.
DBU-promoted cyclization of ortho-(3-hydroxy-1-alkynyl)benzamide is presented, providing an efficient method for the synthesis of trans-3,4-dihydroisoquinolin-1(2H)-ones and (E)-4-(1-alkenyl)isoquinolin-1(2H)-ones under mild conditions. 相似文献
20.
[reaction: see text] The coupling of 2-(1-alkynyl)-2-alken-1-ones with nucleophiles, either catalyzed by AuCl3 or induced by an electrophile, provides highly substituted furans in good to excellent yields under very mild reaction conditions. Various nucleophiles, including functionally substituted alcohols, H2O, carboxylic acids, 1,3-diketones, and electron-rich arenes, and a range of cyclic and acyclic 2-(1-alkynyl)-2-alken-1-ones readily participate in these cyclizations. Iodine, NIS, and PhSeCl have proven successful as electrophiles in this process. The resulting iodine-containing furans can be readily elaborated to more complex products using known organopalladium chemistry. 相似文献