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1.
Akira Yanagisawa Prof. Dr. Takahiro Suzuki Takanori Koide Shogo Okitsu Takayoshi Arai Prof. Dr. 《化学:亚洲杂志》2008,3(10):1793-1800
A Barbier‐type regioselective propargylation of aldehydes and ketones with (3‐bromobut‐1‐ynyl)trimethylsilane has been achieved using reactive barium as a low‐valent metal in THF. Especially in the case of ketones, the corresponding homopropargylic alcohols form almost exclusively. In the reaction of α,β‐unsaturated carbonyl compounds, only 1,2‐adducts have been observed. This method is also applicable to propargylation of imines, and the corresponding homopropargylic amines are obtained regiospecifically in good yields with diastereomeric ratios of up to 87:13. 相似文献
2.
Tomomi Kawasaki Miyuki Nagaoka Tomoko Satoh Ayako Okamoto Rie Ukon Atsuyo Ogawa 《Tetrahedron》2004,60(15):3493-3503
Claisen rearrangement triggered by enolization of 2-allyloxyindolin-3-ones with DBU was performed in order to prepare 3-allyl-3-hydroxyindolin-2-ones. Total synthesis of 3-hydroxyindolin-2-one alkaloids, (±)-donaxaridine, as well as (±)-convolutamydines A and E, was achieved by transformation of the allyl moiety of 3-allyl-3-hydroxyindolin-2-ones. 相似文献
3.
Tomomi Ikemoto Tatsuya Ito Atsuko Nishiguchi Kiminori Tomimatsu 《Tetrahedron》2004,60(48):10851-10857
The efficient synthesis of 2,3-dihydro-1-benzothiepine derivatives 4 has been developed. The intramolecular Claisen type reaction of the new products, 4-(o-formylphenylthio)butyrate 9, with alcoholate in dialkylcarbonate as a solvent afforded 4 in good yields. According to this new procedure, we have accomplished the practical preparation of CCR5 antagonist 1 as a candidate for oral HIV-1 therapy. 相似文献
4.
Reaction of a preformed lithium enolate and trimethyl orthoformate with added boron trifluoride leads to the corresponding α-dimethoxymethyl ketone. 相似文献
5.
Important role of molecular permanent dipoles of the Alq3/Al interface studied from first-principles
We have studied the atomic geometries and electronic properties of the tris-(8-hydroxyquinoline) aluminum (Alq3)/Al interface using density functional calculations. The calculated interface dipoles agree reasonably well with the experiments and the origin of the interface dipole formation mainly comes from the alignment of the permanent dipoles of Alq3 molecules. The HOMO levels of the Alq3 molecules significantly depend on the orientation of the molecular permanent dipoles and the interfacial gap state observed by experiments is ascribed to the co-existence of the two orientations of the molecular dipoles. 相似文献
6.
This review covers the literature on simple indole alkaloids and those with a nonrearranged monoterpenoid unit from the beginning up to the end of 2004. Newly isolated alkaloids, structure determinations, total synthesis and biological activities are included. 相似文献
7.
Tomomi KawasakiAtsuyo Ogawa Yasuyuki TakashimaMasanori Sakamoto 《Tetrahedron letters》2003,44(8):1591-1593
A new and efficient total synthesis of (−)-pseudophrynaminol, the pyrrolo[2,3-b]indole alkaloid bearing the allylic moiety at the 3a-position, has been achieved by a sequence involving 3-allylindol-2-one 8 as a key intermediate. The enantioselective construction of the quaternary carbon in 8 was performed through a tandem cascade reaction of 2-allyloxyindolin-3-one 4, olefination, isomerization, and asymmetric Claisen rearrangement. 相似文献
8.
Yuichiro Hori Miyako Nishiura Tomomi Tao Reisuke Baba Steven D. Bull Kazuya Kikuchi 《Chemical science》2021,12(7):2498
Reversible enzymatic post-translational modification of the ε-amino groups of lysine residues (e.g. N-acylation reactions) plays an important role in regulating the cellular activities of numerous proteins. This study describes how enzyme catalyzed N-deprotection of lysine residues of non-fluorescent peptide-coumarin probes can be used to generate N-deprotected peptides that undergo spontaneous O- to N-ester transfer reactions (uncatalyzed) to generate a highly fluorescent N-carbamoyl peptide. This enables detection of enzyme catalyzed N-deacetylation, N-demalonylation, N-desuccinylation and N-demethylation reactions activities towards the N-modified lysine residues of these probes using simple ‘turn on’ fluorescent assays.We developed “turn-on” fluorescent probes that detect enzymatic lysine deacylation and demethylation critical for epigenetic and other cellular phenomena, using intramolecular O- to N-ester transfer reactions. 相似文献
9.
S. Momota Y. Nojiri M. -B. Tanaka T. Yanagisawa M. Fukuda K. Matsuta T. Minamisono 《Hyperfine Interactions》1993,80(1-4):1275-1279
To disclose the basic mechanisms of nuclear polarization creation realized by the tilted foil technique, hyperfine quantum beats of the nuclear polarization of the short-lived beta-emitter8Li(I
=2+,T
1/2=840 ms) were measured as a function of the distance between two tilted foils. From the observed beats of the8Li nuclear polarization, it was found that the Fermi-contact interaction of the8Li nucleus with the ground 1s-electron in LiIII plays a main role in the final stage of polarization transfer from polarized orbital electrons to the8Li nucleus. 相似文献
10.
S. Momota Y. Nojiri M. -B. Tanaka T. Yanagisawa M. -Y. Tanaka M. Fukuda K. Matsuta T. Minamisono 《Hyperfine Interactions》1993,80(1-4):1281-1286
In order to study the basic mechanism of polarization enhancement realized by the multitilted foil technique, nuclear polarization of short-lived beta-emitter8B(T1/2=769 ms,I
=2+) was induced. Utilizing up to ten tilted foils, the polarization enhancement was measured as a function of the foil numbers. The observed enhancement for8B was combined with the previous results for12B(I
=1+,T
1/2=20 ms) which has the same atomic configurations but different nuclear spin. Analyzing these results in the framework of the classical vector model, the essential features of the enhancement depending on the nuclear spin was disclosed. 相似文献