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1.
Ignacio H. Sánchez María Isabel Larraza Fernande Basurto Ricardo Yaf?ez Salvador Avila Ricardo Tovar Pedro Joseph-Nathan 《Tetrahedron》1985,41(12):2355-2359
(±)--methylperezone () was obtained by selective oxidative demethylation of (±)-leucoperezone trimethyl ether (). Compound () was prepared by condensation of 2,3,5-trimethoxytoluene () with 6-methyl-5-hepten-2-one, followed by reductive removal of the tertiary alcohol. The aromatic precursor was prepared in four steps from 2,3-dimethoxytoluene () and, alternatively, in three steps from 5-bromoveratraldehyde (). Racemic and were directly compared with the optically active molecules prepared from natural R(-)-perezone (). 相似文献
2.
A new synthesis of (±), (+)- and (-)-lineatin (3,3,7-trimethyl-2, 9-dioxatricyclo [3.3.1.04,7] nonane, ) was achieved. The stereochemistry of (+)-lineatin was established as 1, 4, 5, 7 by an X-ray crystallographic analysis of an intermediate . 相似文献
3.
Makoto Ojika Yoshikazu Shizuri Haruki Niwa Kiyoyuki Yamada Shuichi Iwadare 《Tetrahedron letters》1982,23(47):4977-4980
The structure of reductiline, a metabolite of a variant of was elucidated as () based on chemical and spectroscopic evidence. Transformation of an antitumor antibiotic reductiomycin () into reductiline () was carried out. Synthesis of reductiline () was achieved starting from β-cyanopropionaldehyde dimethylacetal. 相似文献
4.
The synthesis of the 2,4,6-cycloheptatrienyl ketones – by two alternative routes is reported: Route 1): The adducts from the phenyl(trimethylsiloxy)-acetonitriles , known as “umpolung” reagents, and tropylium tetrafluoroborate are cleaved by triethylammonium fluoride to form the aromatic cycloheptatrienyl ketones –. Route 2): the phenyl, methyl, and cyclopropyl ketone (, , ) are prepared by treatment of the acid chloride with the corresponding organomanganese iodides RMnI (, , ). The Fe-catalyzed coupling reaction of the acid chloride with a Grignard reagent was also used for the preparation of ketone . 相似文献
5.
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
6.
The photochemical behavior of -1,2-dihydrophthalide () and its 1,2-trimethylene derivative () was studied. Besides bicyclo[2.2.0]hexene formation in both cases, () transforms into its isomer () whereas () undergoes a 1,2-shift to (). 相似文献
7.
Biogenetic-type synthesis of (±)-dictyopterene A () was achieved employing 1,-5-undecadien-3-ol () postulated to be a biosynthetic intermediate of : this synthesis means that transformation of dictyoprolene () into dictyopterene A () was formally made. 相似文献
8.
An azaanalog of adamantene, 2-azaadamant-1-ene () and 4-azaprotoadamant-3-ene () were generated in the nonstatistical ratio via photolysis of 3-azidonoradamantane (). The highly strained and could not be isolable but were trapped by MeOH. Acidolysis of was also reported, and discussed in comparison with the photolysis. 相似文献
9.
10.
Marino Cavazza Maurizio Zandomeneghi Crescenzo Festa Enrico Lupi Manuela Sammuri Francesco Pietra 《Tetrahedron letters》1982,23(13):1387-1390
The optical activity of (1,5-1-methoxybicyclo[3.2.0]hepta-3,6-dien-2-one () is determined by partial photoresolution of the racemate with circularly polarized laser light; although a rearranged, optically active product was also formed, isolation of the enantiomers was note required. 相似文献
11.
《Tetrahedron》1986,42(16):4413-4420
(2,3,1')-Stegobinone [2,3-dihydro-2,3,5-trimethyl-6-(1'-methyl-2'-oxobutyl)-4H-pyran-4-one], the pheromone of L., was synthesized with stereocontrol at C-2 and C-1' starting from ethyl ()-3-hydroxybutanoate and methyl ()-3-hydroxy-2-methylpropanoate. The dihydro-γ-pyrone ring of the pheromone was constructed by an intramolecular acylation followed by acid-catalyzed cyclization. 相似文献
12.
Jack E. Baldwin Robert M. Adlington Bernard J. Rawlings Richard H. Jones 《Tetrahedron letters》1985,26(4):485-488
Practical procedures for the resolution of racemic modification of (1, 2)-and (1, 2)-1-amino-2-ethylcyclopropane-1-carboxylic acid ,,(1, 2)- and (1, 2)-1-amino-2-methylcyclopropane-1-carboxylic acid ,, and (1, 2)- and (1, 2)-1-amino-2-methylcyclopropane-1-carboxylic acid , are described; the structures as ,, and were confirmed by X-ray-crystallographic methods. 相似文献
13.
Ihsan Erden Armin de Meijere Gérard Rousseau Jean Marie Conia 《Tetrahedron letters》1980,21(26):2501-2504
Upon photooxidation bicyclopropylidene () yields spiro[2.3]hexan-4-one () and 7-oxatrispiro[2.0.2.1]heptane (). The formation of these is rationalized. Authentic was prepared by epoxidation of , and by isomerization of . 相似文献
14.
1-Methyl-2-(1′-cyano-1′-trimethylsilyloxy)alkyl-1H-imidazoles () were easily prepared from the corresponding stable carbonyl compounds, 1-methyl-2-acyl- 1H-imidazoles (). When the quarternary salts of were treated with various nucleophiles, reactive acyl species, which was presumed to be acylcyanide (), was generated in situ under CC bond fission to result in producing the corresponding acylated compounds (–) in good yields. 相似文献
15.
Tetsuji Kametani Keiichiro Fukumoto Hiroshi Kurobe Hideo Nemoto 《Tetrahedron letters》1981,22(37):3653-3656
The acid catalysed cyclization of β-hydroxy selenide (), which was prepared from nerolidol () the epoxide (), was carried out to give bicyclic ether () directly which was further transformed into caparrapl oxide (). 相似文献
16.
A preparative route to cis- and trans-1,2-dibromocyclopropane () was developed via the Hunsdiecker reaction of silver cyclopropane-1,2-dicarboxylate (). Cis- and trans- gave the same ratio of cis- and trans- (1:3.2). The mechanism of this reaction is briefly discussed. 相似文献
17.
Hisashi Ishii Tsutomu Ishikawa Ih-Sheng Chen Sheng-Teh Lu 《Tetrahedron letters》1982,23(42):4345-4348
The structures of three new prenylphenyl propanoids, wutaiensol (), wutaiensal (), and methyl demethoxywutaiensate () were established by correlating with S-rutaretin methyl ether () or S-marmesin () by chemical means. The structure of wutaialdehyde (), a related compound, was also established by total synthesis of the racemate and by correlating with . Preliminary piscicidal test on these compounds disclosed that and are weakly bu distinctly positive. 相似文献
18.
Yoshikatsu Ito Meng Ji-Ben Shin Suzuki Yoshitaka Kusunaga Teruo Matsuura Keiichi Fukuyama 《Tetrahedron letters》1985,26(17):2093-2096
In contrast to simple imidazoles, 1-methy1–2,4,5-triphenylimidazole () produced stable oxetane photoadducts - with good efficiency upon irradiation in the presence of benzophenone derivatives - in acetonitrile solution. Irradiation in the solid-phase was also studied. The oxetanes - readily underwent cycloreversion by acid catalysis or by heating. 相似文献
19.
Methyl 4-0-benzoyl-6-bromo-6-deoxy-α-D-glucopyranoside (, Figure 1) was converted, via the corresponding ditosylate , into methyl 2,3-di-0-p-toluenesulfonyl-4-0-benzoyl-6-S-acetyl-6-thio-α-D-glucopyranoside () by a selective nucleophilic displacement of 6-bromo-group with thioacetate. Unexpectedly, on treating the compound with an excess of sodium methoxide in benzene-methanol (1:1) at room temperature, methyl 2-0-p-toluenesulfonyl-4,6-thioanhydro-α-D-gulopyranoside () was obtained in a yield of 84%. In order to determine the structure of the relatively unstable oily product , some stable crystalline derivatives (, and ) were prepared. Detailed analysis of the 1H-NMR-spectra (200 MHz) of and gave the conclusive evidence for the structure of A self-imposing mechanism of the clean and smooth transformation of to is proposed, involving: a) formation of (Figure 2) as a crucial intermediate and b) a highly regioselective epoxide opening in (at C-4) by an intramolecular nucleophilic attack of the mercaptide anion from C-6. 相似文献
20.