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1.
μ-Carbonyl(Rh? Rh)di(η5-indenyl)[(2R,3S)-C,2,3,C-η-(2,3,4,5-tetramethylidenebicyclo[2.2.1]heptan-7-one)]]-dirhodium(I)(Rh? Rh) (7) and cis-μ-[(2R,3S,5R,6S))-C,2,3,C-η:C,5,6,C-η-(2,3,5,6-tetramethylidenebicyclo[2.2.1]heptan-7-one)]bis[μ-carbonyldi(η5-indenyl)dirhodium(I)(Rh? Rh)] ( 8 ) have been prepared. Complex 7 reacts with Fe2(CO)9 in hexane/MeOH and gives cis-μ-[(2R,3S,5R,6S] ( 9 ), trans-μ-[(2R,3S,5S,6R)-C,2,3,C-η: C,5,6, C-η-(2,3,5,6-tetramethylidenebicyclo[2.2.1]heptan-7-one)-μ-carbonyldi(η5-indenyl)dirhodium(I)(Rh? Rh)-(tricarbonyliron) ( 10 ), and, μ-carbonyl(Rh? Rh)[(2R,3S)-C,2,3,C-η-(2,3-dimethyl-5,6-dimethylidenebicyclo-[2.2.1]hept-2-en-7-one)]di(η5-indenyl)dirhodium(I)(Rh? Rh) ( 11 ). Treatment of 7-oxa[2.2.1]hericene ( 4 ) with Fe2(CO)9 or (cyclooctene)2Fe(CO)3 gave a 1:2 mixture of cis-μ-[(2R,3S,5R,6S)-] ( 12 ) and trans-μ-[(2R,3S,5S,6R)-C,2,3,C-η:C,5,6,C-η-(2,3,5,6-tetramethylidenebicyclo[2.2.1]heptan-7-one)]bis(tricarbonyliron)( 13 ). 相似文献
2.
Epoxidation of (?)-(1R,2R,4R)-2-endo-cyano-7-oxabicyclo[2.2.1]hept-5-en-2-exo-yl acetate ((?)-5) followed by saponification afforded (+)-(1R,4R,5R,6R)-5,6-exo-epoxy-7-oxabicyclo[2.2.1]heptan-2-one ((+)-7). Reduction of (+)-7 with diisobutylaluminium hydride (DIBAH) gave (+)-1,3:2,5-dianhydroviburnitol ( = (+)-(1R,2R,3S,4R,6S)-4,7-dioxatricyclo[3.2.1.03,6]octan-2-ol; (+)-3). Hydride reductions of (±)-7 were less exo-face selective than reductions of bicyclo[2.2.1]heptan-2-one and its derivatives with NaBH4, AlH3, and LiAlH4 probably because of smaller steric hindrance to endo-face hydride attack when C(5) and C(6) of the bicyclo-[2.2.1]heptan-2-one are part of an exo oxirane ring. 相似文献
3.
José M. Otero José C. Barcia Cristian O. Salas Pablo Thomas Juan C. Estévez Ramón J. Estévez 《Tetrahedron》2012,68(5):1612-1621
A strategy for the synthesis of the novel (6bR,7R,8S,9S,10S,10aR)-8-(benzyloxy)-7,9,10-trihydroxy-6b,7,8,9,10,10a-hexahydro-11H-benzo[a]carbazole-5,6-dione is reported. The key steps were the Michael addition of 2-hydroxy-1,4-naphthoquinone to 1-nitrocyclohexene or 3-O-benzyl-5,6-dideoxy-1,2-O-isopropylidene-6-nitro-α-d-xylo-hex-5-enefuranose and the diastereoselective intramolecular Henry reaction of 3-O-benzyl-5,6-dideoxy-5-C-(3′-hydroxy-1′,4′-naphthoquinon-2′-yl)-1,2-O-isopropylidene-6-nitro-α-d-glucofuranose to give the key (1S,2S,3S,4R,5R,6R)-3-(benzyloxy)-1,2,4-trihydroxy-5-(3′-hydroxy-1′,4′-naphthoquinon-2′-yl)-6-nitrocyclohexane. When 2-hydroxy-1,4-naphthoquinone was replaced by (1,4-dimethoxynaphthalen-2-yl)lithium, the novel (1R,2S,3S,4R,4aS,11bS)-2-(benzyloxy)-1,3,4-trihydroxy-1,2,3,4,4a,5-hexahydro-11bH-benzo[b]carbazole-6,11-dione was obtained. 相似文献
4.
Pter Molnr Jzsef Deli Zoltn Matus Gyula Tth Andrea Steck Hanspeter Pfander 《Helvetica chimica acta》1997,80(1):221-229
β-Cryptoxanthin ( 1 ) was acetylated and then epoxidized with monoperoxyphthalic acid. After hydrolysis, repeated chromatography, and crystallization, (3S,5R,6S)-5,6-epoxy-β-cryptoxanthin ( 3 ), (3S,5S,6R)-5,6-epoxy-β-cryptoxanthin ( 4 ), (3R,5′R,6′R)-5′,6′-epoxy-β-cryptoxanthin ( 5 ), (3S,5R,6S,5′R,6′S)-5,6:5′,6′-diepoxy-β-cryp-toxanthin ( 6 ), and (3S,5S,6R,5′S,6′R)-5,6:5′,6′-diepoxy-β-cryptoxanthin ( 7 ) were isolated as main products and characterized by their UV/VIS, CD, 1H- and 13C-NMR, and mass spectra. The comparison of the carotenoid isolated from yellow, tomato-shaped paprika (Capsicum annuum var. lycopersiciforme flavum) with 3–5 strongly supports the structure of 3 for the natural product. 相似文献
5.
The structural characteristics of (±)-(exo,exo)-3-(hydroxymethylene)-5,6-(isopropylidenedioxy)bicyclo[2.2.1]heptan-2-one make the reactions between this β-diketone and hydrazines particularly interesting for elucidating the mechanism of pyrazole formation. The isolation and X-ray structure determination of two 5-hydroxy substituted Δ2-pyrazolines [(±)-(3aR*,4R*,5R*,6S*,7R*,7aR*)-7a-hydroxy-5,6-(isopropylidenedioxy)-3a,4,5,6,7,7a-hexahydro-4,7-methano-1H-indazole] and [(±)-(3aS*,4R*,5R*,6S*,7R*,7aR*)-7a-hydroxy-5,6-(isopropylidene-dioxy)-1-phenyl-3a,4,5,6,7,7a-hexa-hydro-4,7-methano-1H-indazole] has been determinant for proposing a mechanism. Besides B3LYP/6-31G* calculations have been carried out on all intermediate dihydroxypyrazolidines and 5-hydroxypyrazolines. Finally, the annular tautomerism of the NH-methanotetrahydroindazoles has been studied both experimentally (13C NMR) and theoretically: the Mills-Nixon effect favours the 2H-tautomer. 相似文献
6.
Anastasia A. Fesenko 《Tetrahedron letters》2007,48(48):8420-8423
A three-stage diastereoselective synthesis of (4R∗,5R∗,6S∗)-5-mercapto-4-methyl-6-phenylhexahydropyrimidin-2-one has been developed. The first stage involves the formation of 4-hydroxy-5-(4-methoxybenzylthio)-4-methyl-6-phenylhexahydropyrimidin-2-one by the reaction of N-[(phenyl)(tosyl)methyl]urea with the sodium enolate of 1-(4-methoxybenzylthio)propan-2-one. Reduction of the obtained compound by NaBH4-CF3COOH and removal of the p-methoxybenzyl protecting group results in the target compound. 相似文献
7.
( all-E)-12′-Apozeanthinol, Persicaxanthine, and Persicachromes Reexamination of the so-called ‘persicaxanthins’ and ‘persicachromes’, the fluorescent and polar C25-apocarotenols from the flesh of cling peaches, led to the identification of the following components: (3R)-12′-apo-β-carotene-3,12′-diol ( 3 ), (3S,5R,8R, all-E)- and (3S,5R,8S,all-E)-5,8-epoxy-5,8-dihydro-12′-apo-β-carotene-3,12′-diols (4 and 5, resp.), (3S,5R,6S,all-E)-5,6-epoxy-5,6-dihydro-l2′-apo-β-carotene-3,12′-diol =persicaxanthin; ( 6 ), (3S,5R,6S,9Z,13′Z)-5,6-dihydro-12′apo-β-carotene-3,12′-diol ( 7 ; probable structure), (3S,5R,6S,15Z)-5,6-epoxy-5,6-dihydro-12′-apo-β-carotene-3,12′-diol ( 8 ), and (3S,5R,6S,13Z)-5,6-epoxy-5,6-dihydro-12′-apo-β-carotene-3,12′-diol ( 9 ). The (Z)-isomers 7 – 9 are very labile and, after HPLC separation, isomerized predominantly to the (all-E)-isomer 6 . 相似文献
8.
Raphy Gabioud Pierre Vogel Alan A. Pinkerton Dieter Schwarzenbach 《Helvetica chimica acta》1986,69(2):271-282
The preparation and the CD spectra of optically pure (+)-trans-μ-[(1R,4S,5S,6R,7R,8S)-C,5,6,C -η : C,7,8,C-η-(5,6,7,8-tetramethylidene-2-bicyclo [2.2.2]octanone)]bis(tricarbonyliron) ((+)- 7 ) and (+)-tricarbonyl[(1S,4S,5S,6R)-C-5,6,C-η-(5,6,7,8,-tetramethylidene-2-bicyclo[2.2.2]octanone)]iron ((+)- 8 ), and of its 3-deuterated derivatives (+)-trans-μ-[(1R,3R,4S,5S,6R,7R,8S)-C,5,6,C-η : C,7,8,C-η-5,6,7,8-tetramethylidene(3-D)-2-bicyclo[2.2.2]-(octanone)]bis(tricarbonyliron) ((+)- 11 ) and (+)-tricarbonyl[(1S,3R,4S,5S,6R)-C-5,6,C- η-(5,6,7,8-tetramethylidene(3-D)-2-bicyclo[2.2.2]octanone)]iron ((+)- 12 ) are reported. The chirality in (+)- 7 and (+)- 8 is due to the Fe(CO)3 moieties uniquely. The signs of the Cotton effects observed for (+)- 7 and (+)- 8 obey the octant rule (ketone n→π*CO transition). Optically pure (?)-3R-5,6,7,8-tetramethylidene(3-D)-2-bicyclo[2.2.2]octanone ((?)- 10 ) was prepared. Its CD spectrum showed an ‘anti-octant’ behaviour for the ketone n→π*CO transition of the deuterium substituent. The CD spectra of the alcoholic derivatives (?)-trans-μ-[(1R,2R,4S, 5S,6R,7R,8S)-C,5,6,C-η : C,7,8,C- η-(5,6,7,8-tetramethylidene-2-bicyclo[2.2.2]octanol)]bis(tricarbonyliron) ((?)- 2 ) and (?)-tricarbonyl- [(1S,2R,4S,5S,6R)- C,5,6,C- η-(5,6,7,8-tetramethylidene-2-bicyclo[2.2.2]octanol)]iron ((?)- 3 ) and of the 3-denterated derivatives (?)- 5 and (?)- 6 are also reported. The CD spectra of the complexes (?)- 2 , (?)- 3 , (+)- 7 , and (+)- 8 were solvent and temperature dependent. The ‘endo’-configuration of the Fe(CO)3 moiety in (±)- 8 was established by single-crystal X-ray diffraction. 相似文献
9.
《Tetrahedron: Asymmetry》1998,9(21):3789-3795
A synthetic procedure for construction of the (+)-(3R,5R,6R)-5,6-dihydroxy-3,7-dimethyl-octanal and (−)-(3S,5S,6S)-5,6-dihydroxy-3,7-dimethyl-octanal derivatives, the intermediates for synthesis of the HIV-active didemnaketal analogue, was developed via a series of reactions from the natural (−)-menthone. 相似文献
10.
S. Chandrasekhar Ch. Narsihmulu S. Shameem Sultana M. Srinivasa Reddy 《Tetrahedron letters》2004,45(50):9299-9301
Iterative asymmetric allylations and ring-closing metathesis have been effectively performed for the first stereoselective total synthesis of (6S)-5,6-dihydro-6-[(2R)-2-hydroxy-6-phenylhexyl]-2H-pyran-2-one, a novel α,β-unsaturated-δ-lactone having antifungal activity, isolated from Ravensara crassifolia. 相似文献
11.
《Tetrahedron: Asymmetry》2007,18(18):2197-2200
A stereoselective synthesis of (6S)-5,6-dihydro-6-[(2R)-2-hydroxy-6-phenylhexyl]-2H-pyran-2-one is reported. The strategy utilizes an olefin cross-metathesis, syn-benzylidene acetal formation and a preferential (Z)-Wittig olefination reaction and lactonization as the key steps. 相似文献
12.
Humberto E. Ortega Young Yongchun Shen Karen TenDyke Nivia Ríos Luis Cubilla-Ríos 《Tetrahedron letters》2014
A new polyhydroxylated macrolide, named mangiferaelactone (1) was isolated from a solid culture of the endophytic fungus Pestalotiopsis manguiferae, together with ten known compounds [(6S,1′S)-LL-P880α; (6S,1′S,2′R)-LL-P880β; (1′S,2′R)-LL-880γ; (1′R)-dehydropestalotin; (−)-5-carboxylmellein; (−)-5-methylmellein; (−)-5-hydroxylmethylmellein; arabenoic acid; 5,6-dihydro-4-methoxy-2H-pyran-2-one; and the (−)-2-hexylidene-3-methylsuccinic acid]. P. manguiferae was isolated from Hyptis dilatata, a small shrub common in the central region of Panama. The structure of compound 1 was elucidated by a combination of spectroscopic methods (IR, MS, optical rotation, 1D and 2D NMR spectroscopy). The absolute configuration of 1 was established as 4R,7R,8R,9S by application of vibrational circular dichroism (VCD). Compound 1 showed a minimum inhibitory concentration (MIC) of 1.6863 mg/mL against Listeria monocytogenes, and 0.5529 mg/mL against Bacillus cereus. No activity was observed for compound 1 against Plasmodium falciparum or Trypanosoma cruzi; likewise, no cytotoxic activity was observed against A2058 and H522-T1 cells. 相似文献
13.
Kenji Mori Masayuki Sakakibara Yoshitaka Ichikawa Hiraki Ueda Katsuhide Okada Takeaki Umemura Goro Yabuta Shigefumi Kuwahara Michitada Kondo Masao Minobe Akemi Sogabe 《Tetrahedron》1982,38(14):2099-2109
(22S, 23S)-Homobrassinolide (2α, 3α, 22S, 23S-tetrahydroxy-24S-etyl-B-homo-7-oxa-5α-cholestan-6-one) and brassinolide (2α, 3α 22R, 23R-tetrahydroxy-24S-methyl-B-homo-7-oxa-5α-cholestan-6-one) were synthesized from stigmasterol and shown to promote plant growth. 相似文献
14.
Márta Palkó Gabriella Benedek Enikő Forró Edit Wéber Mikko Hänninen Reijo Sillanpää Ferenc Fülöp 《Tetrahedron: Asymmetry》2010,21(8):957-961
(1R,2S,6R)-2-Amino-6-hydroxycyclooctanecarboxylic acid (?)-10 was synthesized from (1R,2S)-2-aminocyclooct-5-enecarboxylic acid (+)-2 via an iodolactone intermediate, while (1R,2S,3R,4S)-2-amino-5,6-dihydroxycyclooctanecarboxylic acid (?)-12 was prepared by using the OsO4-catalyzed oxidation of Boc-protected amino ester (?)-5. The stereochemistry and relative configurations of the synthesized compounds were determined by 1D and 2D NMR spectroscopy (based on 2D NOE cross-peaks and 3J(H,H) coupling constants) and X-ray crystallography. 相似文献
15.
Masao Hirotani Miyuki Masuda Aya Sukemori Seiko Hirotani Noriko Sato Takafumi Yoshikawa 《Tetrahedron》2005,61(1):189-194
Agariblazeispirol C, which has a unique steroidal skeleton, has been isolated from the cultured mycelia of Agaricus blazei (Agaricaceae). The structure of agariblazeispirol C was established to be (23S,24S)-13,23-cyclo-25-hydroxy-14β-methyl-18-nor-des-A-ergosta-5,7,9,11,17(20)-pentaen-22-one by comparison of extensive 1D and 2D NMR spectral data with those of agariblazeispirols A and B. At the same time, agariblazeispirol C was synthesized by the reaction of blazeispirol A with BF3·OEt2 along with some interesting compounds. 相似文献
16.
Two new C12-ketones, (+)-(1S, 10R)-1,10-dimethylbicyclo[4.4.0]dec-6-en-3-one ( 5 ) and (+)-(6S, 10S)-6,10-dimethylbicyclo[4.4.0]dec-1-en-3-one ( 6 ), have been isolated from Reunion vetiver oil (Vetiveria zizanioides (L.) Nash). Structure and absolute configuration of 5 were established by a four-step synthesis from (+)-isonootkatone ((+)-α-vetivone) ( 1 ). The structure of 6 followed from its spectroscopic properties and was confirmed by direct comparison with an authentic racemic sample. The absolute configuration of 6 was established by chemical correlation with (+)-α-eudesmol ( 13 ). 相似文献
17.
(5R,6S,5′R,6′S)-5,6,5′,6′-Diepoxy-β,β-Carotene: Synthesis, Spectroscopical and Chiroptical Properties, and HPLC-Behaviour Using the scheme C13 + C2→C15 + C10→C40, whereby C13 = (5R,6S)-5,6-epoxy-β-ionone [8], the title compound 11a , (R = H), has been prepared and characterized. It exhibits nearly identical CD spectra as violaxanthin ( 11b , R = OH). 相似文献
18.
Annukka Kallinen Jan Tois Rainer Sjöholm Robert Franzén 《Tetrahedron: Asymmetry》2010,21(19):2367-2371
Stereoselective synthesis of (5R,6R)- and (5S,6S)-5-benzylamino-6-(tert-butyldimethylsilanyloxymethyl)-5,6-dihydropyran-2-ones starting from d-glucal and furanaldehyde, respectively, is described. The synthesis relies on a Sharpless asymmetric dihydroxylation, an Achmatowicz reaction, and a stereoselective Pd-catalyzed allylic amination as the key steps. 相似文献
19.
Ligia Bicudo de Almeida Marilene De Vuono Camargo Penteado Kenneth L. Simpson George Britton Murat Acemoglu Conrad Hans Eugster 《Helvetica chimica acta》1986,69(7):1554-1558
Luteochrome isolated from the tubers of a white-fleshed variety of sweet potato (Ipomoea batatas LAM .) has been shown by HPLC, 1H-NMR and CD spectra to consist of a mixture of (5R,6S,5′R,8′R)- and (5R,6S,5′R,8′S)- 5,6:5′,8′-diepoxy-5,6,5′,8′-tetrahydro-β,β-carotene ( 1 and 2 , resp.). Therefore, its precursor is (5R,6S,5′R,6′S)-5,6:5′,6′-diepoxy-5,6,5′,6′-tetrahydro-β,β-carotene ( 4 ). This is the first identification of luteochrome as a naturally occurring carotenoid and, at the same time, gives the first clue to the as yet unknown chirality of the widespread β,β-carotene diepoxide. These facts demonstrate that the enzymic epoxidation of the β-end group occurs from the α-side, irrespective of the presence of OH groups on the ring. 相似文献
20.
《Tetrahedron: Asymmetry》2000,11(2):453-464
The conjugate additions of a variety of organocopper reagents or dimethyl malonate anion to a spirocyclic cyclopent-2-enone connecting a 1,2:5,6-di-O-isopropylidene-α-d-glucofuranosyl ring as a constituent of the spiro structure, namely (1S,3R,4R,5R)-3,4-(isopropylidenedioxy)-1-[(1R)-1,2-(isopropylidenedioxy)ethyl]-2-oxa-spiro[4.4]non-6-en-8-one, proceeded stereoselectively in some cases affording a variety of β-functionalized cyclopentanone derivatives. The thermal treatment of (1S,3R,4R,5R)-7-(hydroxymethyl)-3,4-(isopropylidenedioxy)-1-[(1R)-1,2-(isopropylidenedioxy)ethyl]-2-oxaspiro[4.4]non-6-ene, another d-glucose-derived spirocyclic substrate, with triethyl orthoacetate in the presence of a catalytic amount of acid afforded the Claisen rearrangement product with a high level of diastereoselectivity. 相似文献