共查询到20条相似文献,搜索用时 31 毫秒
1.
Jitsuo Kiji Susumu Yoshikawa Eiichi Sasakawa Satoshi Nishimura Junji Furukawa 《Journal of organometallic chemistry》1974,80(2):267-274
Reaction of butadiene with strained ring olefins such as norbornene, dicyclopentadiene etc. Gives an exo-methylene- and methyl-substituted four-membered cyclic compound (II). The effective catalysts are (n-Bu3P)2NiBr2/NaBH4 or /alkoxide syn-π-crotylbis(triethyl phosphite)nickel hexafluorophosphate (IV), and tetrakis(triethyl phosphite)nickel/CF3COOH . π-Crotyl complex IV reacts with the strained ring olefins to give the corresponding product similarly. It is concluded that the active species for this catalytic reaction is a nickel hydride and that this reaction proceeds through π-crotyl intermediate. 相似文献
2.
The -octalinone 1, derived from p-benzoquinone and butadiene, was transformed via a Michael-alkylation sequence to the key triene precursor 5b in a total synthesis of the HMG-CoA reductase inhibitor compactin. 相似文献
3.
Total synthesis of (±) compactin and its natural (+) enantiomer has been achieved via a multistep sequence originating from butadiene and p-benzoquinone. 相似文献
4.
Christina Moberg 《Tetrahedron letters》1981,22(48):4827-4830
Tertiary allylic amines react with butadiene in the presence of palladium(O) with cleavage of the carbon-nitrogen bond of the allylic amine and formation of the unsaturated tertiary amine . 相似文献
5.
A 20-deethyl 3-oxo vincadifformine was synthesized via condensation of 2-hydroxy tryptamine with synthon . It was further alkylated to the oxo-pseudovincadifformine . The given relative configurations remain hypothetical. 相似文献
6.
Yoshiro Kobayashi Akira Ando Kosuke Kawada Itsumaro Kumadaki 《Journal of fluorine chemistry》1980,16(6):505
Tetrakis(trifluoromethyl)Dewar thiophene () is found to be a good dipolarophile and dienophile. Therefore, reacts with any kind of azides to give 1,3-dipolar cycloadducts, which are transformed to tetrakis(trifluoromethyl)Dewar pyrroles (), compounds of a new cyclic ring system. Further, reacts with cyclic or acyclic dienes to give Diels-Alder adducts. The adduct () of with butadiene was transformed to tetrakis(trifluoromethyl)cyclooctatetraene () by desulfurization, bromination and dehydrobromination, stepwise. Valence-bond isomerisation of will be presented. 相似文献
7.
A tritriacontanucleotide which has the sequence of the 5half molecule of E.coli glycine tRNA2, was synthesized by the phosphotriester method involving p-anisidate protection for the 3phosphate ends. Di- and trinucleotide units were prepared from 5dimethoxytrityl-2O-tetrahydrofuranyl-3?-O-(o-chlorophenyl)phosphoryl derivatives of uridine, N-benzoylcytidine, N-benzolyadenosine and N-iso-butyrylguanosine by condensation with 35unprotected nucleosides followed by phosphorylation to give 3phosphodiester blocks. The 3terminal dimers and trimers were synthesized by using 3(o- chlorophenyl)phosphoro-p-anisidates instead of 3?,5?-unprotected nucleosides. The 3?-phosphodiesters of oligonucleotides with a chain length of larger than 5 were obtained by removal of the 3?-phosphoro-p-anisidate with isoamyl nitrite. The 5dimethoxytrityl group was removed by treatment with zinc bromide under anhydrous conditions. Fragments were designed to use common dimer blocks and to reduce the step for 5deblocking of larger fragments. Finally a 3phosphodiester block with a chain length of 20 was condensed with a 5OH component (tridecanucleotide). The fully protected 33 mer was deblocked and purified by chromatography. The structural integrity of the product was confirmed by mobility shift analysis and complete digestion with RNase T2. 相似文献
8.
Judith Polonsky Jacqueline Gallas Jeannette Varenne Thierry Prangé Claudine Pascard Henri Jacquemin Christian Moretti 《Tetrahedron letters》1982,23(8):869-872
Karinolide is a structurally novel C20 quassinoid isolated from the French Guyanan Simaroubaceae, Simaba multiflora A.Juss. whose structure was established by X-ray diffraction analysis. 6α-Senecioyloxychaparrin , the known 6α-senecioloyxychaparrinone and 9-methoxycanthin-6-one were also isolated ; their structure were determined by spectral means. 相似文献
9.
4-O-(2,6-diamino-2,3,4,6-tetradeoxy-3-C-methyl-β-L-arabino and lyxo-hexopyranosyl) and 4-O-(2-amino2,3,4,6-tetradeoxy-5-c-methyl-L-threo-hexopyranosyl-6-O-(3-amino-3-decxy-α-D-glucopyranosyl)-2-deoxystreptamine (, and ) were synthesized from a kanamycin B derivative () by regiospecific methylation and stereospecific hydrogenation followed by removal of masking groups, converting a D-sugar moiety (4-O-glycoside portion) into L-sugar. The usual conformation of and were determined as boat and skew by 250 MHz PMR spectra respectively. 相似文献
10.
Anna Palumbo Marco dIschia Giovanna Misuraca Giuseppe Prota 《Tetrahedron letters》1982,23(31):3207-3208
Unfertilized sea urchin eggs (Paracentrotus lividus) contain, in addition to glutathione, a new low molecular weight thiol, 1-methyl-5-thiol-l-histidine () which was isolated and characterized as the disulphide by spectral and chemical evidence. 相似文献
11.
Martine Bonin José R Romero David S Grierson Henri-Philippe Husson 《Tetrahedron letters》1982,23(33):3369-3372
The cis 2,6-dialkylpiperidine alkaloid (±) dihydro-pinidine and the trans alkaloid (±) solenopsin A were synthesized from a common α-aminonitrile synthon . The key step in this synthesis was the stereoselective reductive decyanation of the 1-benzyl-2cyano-2′, 6-dialkylpiperidines and . 相似文献
12.
T. Wijchers H.A. Dijkerman P.J.Th. Zeegers C.Th.J. Alkemade 《Spectrochimica Acta Part B: Atomic Spectroscopy》1980,35(5):271-279
CW dye laser induced fluorescence emission and thermal emission spectra of YO-molecules in a 1 atm H2O2Ar flame of 2430 K were recorded simultaneously. Narrow band laser excitation was applied to four rotational lines in the (1, 1) Q-branch of the A2Π→X2Σ+ transition and broadband excitation was applied to several separate Q-branches of the A2Π,→X2Σ+ transitions. From the differences between the fluorescence emission spectra and thermal emission spectra, we conclude that collisional de-excitation of an excited vibronic level takes place by vibrational relaxation, decay to the electronic ground state and by intermultiplet transfer in order of increasing probability. 相似文献
13.
A synthesis of (2S,3S,7S)-3,7-dimethylpentadecan-2-yl acetate () and propionate () is described. (2S)-2-Methyldecan-1-yl lithium () was reacted with (3S,4S)-3,4-dimethyl-γ-butyrolactone () to yield the ketoalcohol which upon Huang-Minlon reduction furnished (2S,3S,7S)-3,7-dimethylpentadecan-2-ol (). Acylations gave the esters and . The (2S)-2-methyldecan-1-yl lithium was obtained via asymmetric synthesis. The chiral lactone was obtained from (2S,3S)-trans-2,3-epoxybutane and dimethyl malonate. 相似文献
14.
Bis(N-(1-benzoyl-2-propylidene)-2-pyridylmethylaminato)iron(III) hexafluorophosphate (Fe(bzpa)2PF6 is shown to be a spin-equilibrium compound between low- (S = ) and high- (S = ) spin states depending on temperature, and to have the unusual property that the relaxation time of the spin change is shorter than the Mössbauer lifetime (1 × 10?7s) of iron- 57 (l = ) in the solid state. 相似文献
15.
Dehydrotripeptides, X-CH(Ri)-ΔPhe-CH(Rk)COOMe (: X = tBOC-NH,CBZ-NH, CF3CONH and N3), were employed for the asymmetric hydrogenation catalyzed by chiral rhodium complexes and it was found that tBOC- brought about by far the best results. Stereoselective dideuteration of a tBOC- was successfully performed. 相似文献
16.
Judith Polonsky Zoīa Varon Thierry Prange Claudine Pascard Christian Moretti 《Tetrahedron letters》1981,22(37):3605-3608
Simarinolide and Guanepolide are new quassinoids with a C25 basic skeleton isolated from a member of the French Guyanan Simaroubaceae, Simaba cf orinocensis H.B.K. The structure was established by spectral means and that of by X-ray diffraction analysis. The previously known simarolide was also isolated. 相似文献
17.
A. Zanarotti 《Tetrahedron letters》1982,23(38):3963-3964
Vinyl quinone methide () reacts with polyphenols to give cinnamylphenols () and neo-flavanoids (). Oxidation of cinnamylphenol (b) leads to malvidin () via the isolated intermediate flav-3-en-3o1 (b). 相似文献
18.
Some advances in the liquid-phase autoxidation of organic compounds of the non-transitional elements
Yu.A. Alexandrov 《Journal of organometallic chemistry》1973,55(1):1-40
Dicrotylzinc (I) adds to CC double bonds in olefins even at temperatures between 20 and 60°. With ethylene bis(3-methyl-4-pentenyl)zinc (II) is formed selectively, and with 1-octene the adduct as which is derived from the 1-methyl-2-propenyl form of (I) is formed almost exclusively. In the reactions with styrene and butadiene metal-to-C(1) addition competes with metal-to-C(2) addition: with butadiene, products which are derived from the 2-butenyl structure of (I) are formed in only 3–13% yield. In comparison with crotylmagnesium and crotylaluminium, (I) reacts more selectively to give products derived from the 1-methyl-2-propenyl form. 相似文献
19.
The copolymerizations of N-(3-dimethylaminophenyl) maleimide (I) and 4-(2-chlorophenyl)azo-3-maleimido-N,N-dimethylaniline (II) with styrene were investigated; the copolymerization parameters of the pairs () and () and hr I at 50° were determined; chain transfer to the maleimide ring of I was proved. The homopolymerization of styrene in the presence of 4-(2-chlorophenyl)azo-succinimide-N,N-dimethylaniline (III) was used to determine the ratio of the rate constant for addition of the polystyrene radical to the azo group in III to kp for styrene. 相似文献
20.
Edmond Amouyal Bertrand Zidler Patrick Keller Alec Moradpour 《Chemical physics letters》1980,74(2):314-317
Rate constants kq for the quenching of the excited state of Ru(bipy)32+ by a series of viologen salts having different redox potential E have been determined in deaerated aqueous solutions at pH = 5 by laser flash photolysis. The kq values are found to decrease with increasing —E and to correlate with the reaction free-energy change ΔG. Such a correlation is shown to be consistent with the Rehm—Weller model for electron-transfer reactions. 相似文献