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1.
Grigorieva N. Ya. Popovsky V. A. Stepanov A. V. Kolotyrkina N. G. 《Russian Chemical Bulletin》2010,59(4):848-851
(2E,4E)-5-Aryl-2-(2-benzyloxyethyl)penta-2,4-dien-1-als (aryl is phenyl and 4-methox-yphenyl) were reduced with NaBH4 quantitatively and stereospecifically to the corresponding penta-2(E),4(E)-dien-1-ols. The hydroxymethyl group in the latter was transformed into a methyl one with a stereoselectivity of 92–97%.
Debenzylation of the resulting (1E,3Z)-1-aryl-6-benzyloxy-4-methylhexa-1,3-dienes with AlCl3 in the presence of PhNMe2 afforded the target (3Z,5E)-6-aryl-3-methylhexa-3,5-dien-1-ols; the configuration of the C=C bonds in the conjugated aryl diene systems was retained
at 95%. 相似文献
2.
T. Tanaka N. Okamura K. Bannai A. Hazato S. Sugiura K. Manabe S. Kurozumi 《Tetrahedron letters》1985,26(45):5575-5578
(5)-Prostaglandin E2 methyl ester was synthesized from ()-4--butyldimethylsiloxy-2-cyclopentenone by 2-alkenyloxycarbonylation of the organocopper conjugate-addition adduct followed by intramolecular palladium-catalyzed decarboxylative 2-alkenylation. A ()-2-butenylated cyclopentanone derivative was obtained from either 2-[()- or ()-2-butenyloxy-carbonyl]cyclopentanone derivative under the similar reaction condition. 相似文献
3.
Asymmetric cyclizations of methyl (E)-3-oxo-9-phenoxy-7-nonenoate () or methyl (E)-3-oxo-9-(methoxycarbonyl)oxy-7-nonenoate () without added base were carried out in the presence of a catalytic amount of palladium(II) acetate and chiral diphosphine as ligands. Allylic carbonate reacted by use of Pd(OAC)2-(S)-(R)-BPPFA at room temperature to give (R)-3-vinylcyclohexanone (), after decarboxylation, in up to 48% e. e. 相似文献
4.
(±)-Isoagatholactone and (±)-12α-hydroxyspongia-13(16),14-dien , a fundamental skeleton of spongiadiol and its congeners, have been synthesized from (±)-labda-8(20),13-dien-15-oic acid . 相似文献
5.
M. Vairamani M. Saraswathi G. K. Viswanadha Rao 《Journal of mass spectrometry : JMS》1991,26(9):786-788
Dibromoethane chemical ionization mass spectra of ten pairs of methyl (E)- and (Z)-cinnamates were studied. C2H4Br+ ion forms stable adducts with E-isomers and the adducts of Z-isomers show preferential loss of methanol. The observed results suggest that the probability of ring alkylation is greater than with the carbonyl group. 相似文献
6.
(±)-Ascochlorin, 5-chloro-2, 4-dihydroxy-6-methyl-3-[(2, 4)-5-(1,2,6-trimethyl-3-oxocyclohexyl)3-methyl-3,4-pentadienyl] benzaldehyde, was synthesized in 14 steps from (±)-3,4-dimethyl-2-cyclohexenone. 相似文献
7.
Sadao Miki Toshinobu Ohno Hideaki Iwasaki Zen-ichi Yoshida 《Tetrahedron letters》1985,26(29):3487-3490
Co(II)TPP1 - catalysed isomerization of a series of electronegative substituted quadricyclanes() to the corresponding norbornadiene() was found to proceed via radicophilic attack of the metal to . 相似文献
8.
Allylic oxidation of 6--(3,3-dimethylallyl)adenosine gave () zeatine riboside , which was isomerized to the () isomer by u.v. irradiation. A method for the regiospecific 3′--succinoylation of these nucleosides is given. 相似文献
9.
N,N-Dimethylformamide () and N,N-dimethylpivalamide () react with carbonyl chloride isocyanate () in the presence of antimony pentachloride to afford the amino substituted 1-oxa-3-azabutatrienium hexachloroantimonates ,. An X-ray diffraction analysis of confirms the proposed structure. The heterocumulenes , react with aldehydes, ketones and tertiary carboxamides to give the amino substituted 2-azaallenium salts - in high yields. 相似文献
10.
Three new diterpenoids with a substituted α-cyclogeraniol skeleton have been isolated from the umbelliferae (Vahl) Lange, for which the names of magydar-2,13-dien-11,17-diol, , magydar-2,10 (20), 13-trien-17-ol, , and magydar-2,10(20), 13-trien-17-yl acetate, , are proposed. The structures of these substances have been deduced from spectroscopic and chemical data. 相似文献
11.
The cationic cyclization of the carbinol (Z) occurred stereoselectively and resulted in a mixture of the hydrindane and the octalin , both with configuration of side chain and angular methyl group. Cyclization of (E) yielded in and , both with -configuration. The structure of , was proved by transformation to the diketones ,. 相似文献
12.
The reaction of the phosphate with the expoxyaldehyde is reported as the key step in a novel stereospecific synthesis of (±)-LTA4, methyl ester . 相似文献
13.
Malcolm R. Binns Richard K. Haynes Dale E. Lambert Paul A. Schober 《Tetrahedron letters》1985,26(28):3385-3388
The enolates generated by the conjugate addition of 1-(phenylthio)-2-octenyllithium to 4--butoxycyclopent-2-en-1-one and <-crotonolactone react with methyl 7-halohept-5-ynoates in the presence of Ph3SnCl to deliver products which may be converted into prostaglandin precursors. 相似文献
14.
Total synthesis of (±)-sesbanine () was carried out using γ-addition of ketene silyl acetal of methyl 3-cyclopentenecarboxylate to quaternized methyl nicotinate. The resulting 1,4-dihydropyridine () was oxidized with DDQ to give 4-substituted nicotinate () and was converted to alcohol () by stereoselective oxymercuration followed by treatment with ammonia to give . 相似文献
15.
16.
Kenji Mori 《Tetrahedron》2012,68(7):1936-1946
The enantiomers of methyl (E)-2,4,5-tetradecatrienoate (1), a component of the male pheromone of Acanthoscelides obtectus, were synthesized from the enantiomers of 1-undecyn-3-ol (6), which were obtained via asymmetric acetylation of (±)-1-trimethylsilyl-1-undecyn-3-ol (4) with vinyl acetate as catalyzed by lipase PS (Amano). The ortho ester Claisen rearrangement of 6 with triethyl orthoacetate was the key-step to generate the chiral allenic system. A new synthesis of (±)-1 was also executed starting from (±)-6. Three different syntheses of methyl (2E,4Z)-2,4-decadienoate (2), another component of the male pheromone of A. obtectus, were achieved by means of either palladium-catalyzed Heck reaction or a Claisen and an Al2O3 catalyzed thermal rearrangements. 相似文献
17.
The rate constants of the (4+2)-cycloaddition reaction between substituted -arenediazocyanides and 2,3-dimethyl-1,3-butadiene have been determined in several solvents. The reaction displays linear Hammett behavior; the data suggest a concerted reaction mechanism. 相似文献
18.
Conjugate addition of O-silylated ketene acetals to α,β-unsaturated carbonyl compounds in acetonitrile gave quantitative yields of the corresponding β-(alkoxycarbonyl)methyl O-silyl enolates . Site specific electrophilic substitutions of yielded the corresponding α-substituted β-(alkoxycarbonyl)-methylalkanones , , and . 相似文献
19.
Synthesis of methyl α-D-tetronitroside() from D-mannose via methyl α-D-mycaroside() established the D-configuration for tetronitrose(kijanose), a novel nitro sugar which occurs as a component of the antitumor antibiotics tetrocarcins A and B, and kijanimicin. 相似文献
20.
Leonid Breydo Charles L. Barnes Kent S. Gates 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(8):o447-o449
In order to characterize the structural elements that might play a role in non-covalent DNA binding by the antitumor antibiotic leinamycin, we have solved the crystal structures of the two leinamycin analogs, methyl (R)-5-{2-[1-(tert-butoxycarbonylamino)ethyl]thiazol-4-yl}penta-(E,E)-2,4-dienoate, C16H22N2O4S, (II), and 2-methyl-8-oxa-16-thia-3,17-diazabicyclo[12.2.1]heptadeca-(Z,E)-1(17),10,12,14-tetraene-4,9-dione, C14H16N2O3S, (III). The penta-2,4-dienone moiety in both of these analogs adopts a conformation close to planarity, with the thiazole ring twisted out of the plane by 12.9 (2)° in (II) and by 21.4 (4)° in (III). 相似文献