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1.
In the presence of titanium tetrachloride, 1,3-bis(trimethylsiloxy)-1-methoxybuta-1,3-diene condenses with hexane-2,5-dione or 2,5-dimethoxytetrahydrofuran to give the 8-oxabicyclo[3.2.1]octyl compounds and respectively, and with 2,6-dimethoxytetrahydropyran to give the 9-oxabicyclo [3.3.1]nonyl derivative . Compound is converted to a compound () which is the 8-oxa analog of cocaine. 相似文献
2.
3.
Refluxing the oximes () of naphtho-[1,8-bc] pyran-3(2H)-one and () of 3 (2H)-benzofuranone with alcoholic hydrogen chloride give the corresponding α-alkoxy-ketones , , and α-chloroketone respectively. This transformation appears to be related to the acid conversion of N-aryhydroxylamines to o. and p. substituted anilines (BAMBERGER réarrangement. 相似文献
4.
dl-[2-13C]Leucine was prepared by condensing the sodium salt of ethyl acetamido-[2-13C]cyanoacetate with isobutylbromide in hexamethylphosphoroustriamide followed by acid hydrolysis. N-Boc-dl-[2-13C]Leucine was prepared and incorporated into [8-dl-[2-13C]leucine]oxytocin by total synthesis. The 13C-labeled hormone derivative [8-[2-13C]leucine]oxytocin was separated from its 8-position diastereoisomer by partition chromatography. The specifically 13C-labeled peptide hormone diastereoisomeric analog [3-dl-[2-13C]leucine]oxytocin also was prepared by solid phase peptide synthesis. No suitable solvent system for partition chromatography separation of the latter diastereoisomeric peptide mixture could be found. However an excellent preparative separation of the diastereoisomers could be obtained by reverse phase high pressure liquid chromatography on a partisil 10 M9 ODS column using the solvent system 0.05 M ammonium acetate (pH 4.0), acetonitrile (81:19, ) to give pure [3-(2-13C]leucine]oxytocin and [3-D-(2-13C]leucine]oxytocin. An excellent separation of [8[2-13C]leucine]oxytocin and the corresponding 8-D-leucine diastereoisomer derivative could also be accomplished by high pressure liquid chromatography. 相似文献
5.
Ernst-Ulrich Würthwein Jayaraman Chandrasekhar Eluvathingal D Jenmis Paul von Ragué Schleyer 《Tetrahedron letters》1981,22(9):843-846
Semi-empirical (MINDO/3 and UNDO) MO calculations on highly strained planar tetracoordinate carbon candidates indicate the central carbons in - [4.4.4.4] fenestrane () to have pyramidal () and in trans-[4.4.4.]fenestrane () to have distorted tetrahedral () geometries. In [2.2.2.2]paddlane (), the two central carbons are pentacoordinate. Each is nearly coplanar with four carbon neighbours; additionally, the two bridgehead carbons are connected by a single bond (). 相似文献
6.
The 185-nm denitrogenation of 2,3-diazabicyclo[2.2.1]heptene () afforded bicyclo[2.1.0]-pentane () and cyclopentene () presumably via a “hot” cyclopentane-1,3-diyl diradical (); 1,4-pentadiene () and methylenecyclobutane () were secondary products of the 185-nm photolysis of () and (). 相似文献
7.
The first syntheses of [1.1.1.1.1]paracyclophane () and [1.1.1.1.1.1]paracyclophane () are described, featuring a trifluoroacetic acid promoted Friedel-Crafts cycloalkylation as the final step. 相似文献
8.
Tsutomu Kumagai Kazuo Shimizu Haruki Tsuruta Toshio Mukai 《Tetrahedron letters》1981,22(49):4965-4968
The valence isomerization reaction of bicyclo[3.2.2]nona-2,6,8-triene (), which photoisomerized to two homologues of semibullvalene, was discussed with the photoreactions of its dihydro-dreivatives, bicyclo[3.2.2]nona-6,8-diene () and bicyclo[3.2.2]nona-2,6-diene (). 相似文献
9.
Farouk Eltayeb Elhadi W. David Ollis J. Fraser Stoddart David J. Williams Kwamena A. Woode 《Tetrahedron letters》1980,21(43):4215-4218
The 1,9,17-triaza[2.2.2]metacyclophane-2, 10, 18-trione derivatives () – () have been synthesised. X-Ray crystallography shows that the 1,9,17-trimethyl derivative () adopts a Crown conformation () in the solid state. Dynamic n.m.r. spectroscopy indicates that both the 1,9-dimethyl-17-benzyl- () and 1,9,17-trimethyl- () derivatives exist as interconverting mixtures of Crown () and Saddle () conformations with the former predominating at equilibrium in solution. 相似文献
10.
L.A.M. Turkenburg P.M.L. Blok W.H. de Wolf F. Bickelhaupt 《Tetrahedron letters》1981,22(34):3317-3320
Base induced elimination of HCl from the dichloro[5.3.1]propellane gives a mixture of [5]metacyclophane () and tetrahydrocyclopentacyclooctenes (), while the stereoisomeric affords quantitatively. 相似文献
11.
Magda A. Abdallah 《Monatshefte für Chemie / Chemical Monthly》2001,29(1):959-965
The reaction of 3-amino-2-thioxo-4(1H)-quinazolinone or its 2-methylthio derivative with hydrazonoyl halides in the presence of ethanol and triethylamine affords
6H-[1,2,4,5]tetrazino[3, 2-b]quinazolin-6-ones. 相似文献
12.
Magda A. Abdallah 《Monatshefte für Chemie / Chemical Monthly》2001,132(8):959-965
Summary. The reaction of 3-amino-2-thioxo-4(1H)-quinazolinone or its 2-methylthio derivative with hydrazonoyl halides in the presence of ethanol and triethylamine affords
6H-[1,2,4,5]tetrazino[3, 2-b]quinazolin-6-ones.
Received January 2, 2001. Accepted (revised) April 11, 2001 相似文献
13.
Ratna Dasgupta Pranab R. Kanjilal Swapan K. Patra Manish Sarkar Usha Ranjan Ghatak 《Tetrahedron》1985,41(23):5619-5625
The efficacy of a new acid-catalyzed intramolecular C-alkylation has been demonstrated by the synthesis of 1-methyl-4--methoxyphenylbicyclo [2.2.2] octan-2-one () and 4--methoxyphenylbicyclo [2.2.2] octan-2-one () from easily accessible starting materials. The carbinol , derived from , undergoes facile rearrangement leading to 1--methoxyphenyl-4-methyl bicyclo [3.2.1] oct-3-ene (), which has been transformed to -1--methoxyphenyl-4-methylbicyclo [3.2.1] octan-3-one (). 相似文献
14.
A new C3-unit substitution reaction at C-4 position of 4- acetoxyazetidinone derivative ( and ) by tetraallyltin () in the presence of 1/10 eq. of BF3-ether in methylene chloride is described. From 4-allylazetidinone derivative () via ylid intermediate () dethiathienamycin () was synthesized. 相似文献
15.
Yoshito Tobe Yasuyoshi Ueda Masaharu Matsumoto Yasuo Sakai Yoshinobu Odaira 《Tetrahedron letters》1982,23(5):537-538
Bicyclo[6.2.2]dodecadienes (), (), and () having two bridgehead double bonds were synthesized by the pyrolysis of the acetate (). 相似文献
16.
Tsutomu Kumagai Akihiko Tokida Kazuo Kidoura Osamu Seshimoto Toshio Mukai 《Tetrahedron letters》1982,23(8):873-876
The reactions of 1H-azepine derivatives ( and ) with singlet oxygen gave the [6+2] cycloadducts () and the [4+2] cycloadducts ( and ). The thermal and base-catalyzed rearrangements of the oxygen-adducts were investigated. 相似文献
17.
The RPX2·AlX3 complex () reacts with unsaturated ketones and imines to give novel 7-oxa and 7-aza-2-phosphabicyclo[2.2.1]heptanes (compounds and respectively).A new 1,3-dipolar addition of (CH3)2 CCH2P?XR to nArN=C=S was disclosed resulting in the formation of the 2-imino-1,3-thiaphospholanes (). 相似文献
18.
Depending upon the experimental conditions, t-butyl (1,5,7,8)-1-ethoxycarbonyl-8-hydroxy-2-oxa-6-azabicyclo[3.2.0]octane-7-carboxylate (2a) reacts with methanesulphonyl chloride to give predominantly the -methanesulphonyl derivative (2b), the -methanesulphonyl derivative (3a), or the -(methanesulphonyl)methane-sulphonyl derivative (6a). 相似文献
19.
4,4-Dimethyl-2-phenyl-2-thiazolin-5-thione () reacts with 2,3-diphenylcyclopropenone () at 145°C and with benzonitrilio-2-propanide () at room temperature to yield the 1,6-dithia-spiro[4.4]nonadienes and , respectively. 相似文献
20.
Tran Quang Minh Léon Christiaens Pierre Grandclaudon Alain Lablache-Combier 《Tetrahedron》1977,33(17):2225-2229
Photoirradiated in presence of acetophenone, benzo[b]selenophene and its 3-methyl derivative add to dimethyl acetylenedicarboxylate. In each ease, the primary reaction product is unstable and has not been isolated. Photoexeited in its triplet state (the energy of which is in the neighbourhood of 69 ) benzo[b]selenophene and its 2- and 3-methyl, 2,3 dimethyl, 3 acetoxy and 2-methyl-3-acetoxy derivatives add to 1,2 dichloroethylene leading to cyclobutanes. Neither cyclo-addition occurs in absence of photosensitiser. Single-crystal X-ray analysis gave the structures of the two adducts of 3-acetoxybenzo[b]selenophene with trans-1,2-dichloroethylene. In both compounds the chlorine atoms are trans. 相似文献