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1.
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
2.
By appropriate choice of reaction conditions, the enantiomerically pure ()-(+)-2-(-tolylsulfinyl)cycloalkenone can be converted into an ()-or an ()-3-substituted cycloalkanone in good to excellent enantiomeric purity. 相似文献
3.
Alkylation of dibutylstannylene complexes of 3,4,6-tri--benzyl--mannopyranose, methyl 6--trityl-α--mannopyranoside and methyl α--mannopyranoside gives respectively β--mannopyranoside and 3--alkyl derivatives with high selectivity. 相似文献
4.
Claudio Fuganti Piero Grasselli Giuseppe Pedrocchi-Fantoni 《Tetrahedron letters》1979,20(26):2453-2454
Feeding experiments with (4) [5-3H;5-14C]-leucine () and with the (4) [5-3H;2-14C]-isomer () show that incorporation into the isoprenylated tryptophan derivative echinuline (), produced by , involves, to a large extent, loss of the fragment enbodying the carbon atom at position 2 of the fed amino acid. 相似文献
5.
The B—A transition has been detected in the emission spectra of ArBr, KrBr, Krl and XeI at low pressure. Comparison with the well-known /ldB–X” continua implies that, in many cases, the latter is heavily overlapped by C—A emission. 相似文献
6.
Pinacol -1-trimethylsilyl-1-propene-3-boronate reacts with aldehydes to form (±)-(*,*)-3-trimethylsilyl-4-hydroxy-1-alkenes, which can be deoxysilylated stereoselectively to either 98% or 99% 1,3-dienes, including the separate components of the red bollworm moth pheromone. 相似文献
7.
Di--alkylamines can be synthesized efficiently by a three-step process: (1) oxidation of a -alkylamine to a -alkylnitroso compound with peracetic acid in ethyl acetate (2) conversion of the -alkylnitroso compound to a tri--alkylhydroxylamine by successive trapping of two -butyl radicals and (3) sodium naphthalide reduction to the di--alkylamine. 相似文献
8.
3-Indazol-3-one has been generated by thermolysis of (-azidobenzoyl)iminopyridinium ylide and trapped as its Diels-Alder cycloadducts with several dienes. 相似文献
9.
Eiichi Kitazawa Akira Ogiso Shuji Takahashi Masaaki Kurabayashi Harumitsu Kuwano Tadashi Hata Chihiro Tamura 《Tetrahedron letters》1979,20(13):1117-1120
Two new diterpenelactones named plaunol A () and B () exhibiting anti-Shay ulcer activity were isolated from Thai medicinal plant, . Structure of was determined by X-ray analysis of its -bromobenzoate and structure of was deduced from the results of chemical correlation and the spectral data. 相似文献
10.
V.I. Kolotyrkin J.A. Kessler V.A. Shchelkotunov I.V. Gordeyev Yu.G. Metlin Yu.D. Tretyakov 《Thermochimica Acta》1981,43(1):27-33
The heat capacity and heat content LiTiO4 and Li2Ti3O7 have been measured in the temperature range 198—960 K. The lattice and dilation contributions to the heat capacity have been estimated. The standard thermodynamic functions and the high temperature enthalpy and entropy have been derived. The lattice heat capacity of LiTiO4 spinel appears to be consistent with the phonon model put forward by Grimes. 相似文献
11.
Richard E. Moore Walter P. Niemczura Oliver C.H. Kwok Suresh S. Patil 《Tetrahedron letters》1984,25(36):3931-3934
The structure of phaseolotoxin, a toxin produced by cultured pv. , the causal agent of halo blight disease in bean plants is revised to 3. The structure of octicidin, isolated from leaves of bean plants infected with pv. . has been determined to be 4, a protease degradation product of 3 which is formed in the plant. 相似文献
12.
The synthesis of 3-vinylindoles through Wadsworth Emmons reactions with 3-formyl and 3-acylindoles is described. Although 3-formylindoles react directly with phosphonate derivatives, 3-acylindoles need prior activation by N-sulphonation. 11-5-Cyanobenzo[]carbazole has been prepared by the oxidative cycloaddition of -3-(indol-3′-yl) propenotrile and benzyne. 相似文献
13.
A stereospecific route to -2,2-dimethyl-3-alkenyl-cyclopropanecarboxylic Acids is illustrated by a total synthesis of (±)--Chrysanthemic Acid (11). The key step consists of an alicyclic Claisen rearrangement of -silyl enolates derived from appropriately substituted ()-4-hexen-6-olides [e.g.(9)]. 相似文献
14.
The reaction of nicotine with -butyllithium gives 6--butylnicotine () and two novel pyrrolidine ring cleaved products, and ; mechanisms for the racemization of , , and were elucidated by reacting -butyllithium with nicotine-2′-d1. 相似文献
15.
O.R. Martin 《Tetrahedron letters》1985,26(17):2055-2058
Upon treatment with tin(IV) chloride, perbenzylated glycofuranosyl acetates such as 3 or 6 undergo an unusual, intramolecular α--arylation resulting from the internal Friedel-Crafts alkylation of the 2--benzyl substituent. 相似文献
16.
The 1H and 13C nmr spectra of , -9-oxobicyclo[3.3.1]nonane-2,4-dicarboxylic acid, 3, in DMSO-d6 or alkaline D2O, clearly show that it exists in a --conformation with carboxyl groups, thus being the first case of - preference of a bicyclo[3.3.1] nonan-9-one due to the presence of ,-2,4- substituents. 相似文献
17.
Naoko Morisaki Jun Furukawa Hisayoshi Kobayashi Shigeo Iwasaki Shigeo Nozoe Shigenobu Okuda 《Tetrahedron letters》1985,26(39):4755-4758
Deuterium labeled -6-protoilludene () was synthesized and fed to the illudin-producing fungus (ATCC 11719). The hydrocarbon () was incorporated into illudin-M () and -S (). 相似文献
18.
The production of I(2P) in the photolysis of CH2I2 has been studied optoacoustically at excitation wavelengths between 365.5 and 247.5 nm. Bands found at 32200 and 47000 cm?1 correlate with I(2P) whilst those at 34700 and 40100 cm?1, which correlate with I(2P), give final 2P/2P ratios of 1.75 and 1.1, respectively, after curve crossing. 相似文献
19.
The N-hydroxyazetidines and are prepared startinfrom 2,3-dihydroazete 1-oxides ( and 0 by reduction with sodium borohydride and by reaction with a nucleophile, respectively. The N-thydroxyazetidines and can be oxidized with mercury (II) oxide to the corresponding nitrones ; oxidation of the N-hydroxyazetidine (unsubstituted at C-4) with equivalent of lead tetraacetate tyields the N-tacetoxy β-lactam . 相似文献
20.
Two steroids, 3-oxo-chol-4-ene-24-oic acid () andi ts unsaturated analog have been isolated from the dorid nudibranch , and the acid has been shown to have antifeedant properties. 相似文献