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41.
42.
Moumita Paira 《Tetrahedron letters》2008,49(15):2432-2434
α-Dehydro-β-amino esters have been synthesized regioselectively from acetates of Baylis-Hillman adducts with amines in the presence of a catalytic amount of ceric ammonium nitrate (CAN) in good yield. The regioselectivity does not differ with respect to the polarity of the solvent. 相似文献
43.
Xin ZHOU Shrong Shi LIN Jin Fang YUAN* Zhe Ming WANG Hong Zhong WANG College of Chemical Molecular Engineering Peking University Beijing Department of Biological Sciences & Biotechnology Tsinghua Univ 《中国化学快报》2001,(10)
A lot of attentions have been paid to the synthesis of benzothiazepines and derivatives1,2 due to their significant physiological activities. It has been reported that b-lactam, a major part of the antibiotic skeleton, can be introduced to a molecule by reaction of an imine moiety with ketene3,4. We introduced a b-lactam skeleton to benzothiazepine and hoped the new compounds may possess certain biological activities. SHNH3ClCHCHCOC2H5OHSNClCla: ortho-Clb: para-Cl+PyridineScheme … 相似文献
44.
Constantin Mamat Markus FrankeTim Peppel Martin KöckerlingJörg Steinbach 《Tetrahedron》2011,67(25):4521-4529
An elegant and efficient synthesis approach for the preparation of novel benzoate and nicotinate containing phosphanes is presented. This reaction path has a broad substrate scope. Thus, various functionalized phosphanes were obtained in high yields using an esterification procedure under Steglich conditions. A facile blocking of the phosphorus atom with BH3 was carried out. BH3 as easily insertable and removable protecting group enables a further derivatization of the benzoate residue. The prepared phosphane derivatives proved to be valuable labeling building blocks for the implementation of a bioorthogonal (radio-)fluorination strategy and were applied for labeling purposes using the traceless Staudinger ligation. For this purpose, a selection of azide-functionalized small organic and bioactive sample molecules was prepared. Furthermore, a mild and selective (radio-)fluorination of these derivatives is demonstrated adopting this bioorthogonal ligation method. 相似文献
45.
Zhen CHEN* Ren Yun WANG Li Lian ZHU Xiao Tian LIANG Institute of Materia Medica Peking Union Medical College The Chinese Academy of Medical Sciences Beijing 《中国化学快报》2001,(4)
When isolating 1,4-dideoxy-1,4-imino-D-arabinitol using Dowex 1(2 (OH- form) or CM-Sephadex C-25 (NH4+ form), we found another compound always accompanied with it. It was apparent that the two compounds had similar structures from their 1HNMR and 13CNMR in D2O (Fig. 1). At first, we guessed the two compounds were isomerides. But when acid was added into the solution of the two compounds, the signals for the minor compound disappeared.Figure 1 13CNMR of 1,4-dideoxy-1,4-imino-D-arabin… 相似文献
46.
Yeasudhasan Christu Rajan 《Tetrahedron letters》2008,49(18):3023-3026
Enantiopure bis-chromanones were prepared from (S)-Binol and bromo esters via a Baylis-Hillman approach. Chiroptical studies indicate that the two-naphthyl units of the chromanone system are non-coplanar. 相似文献
47.
Sun Pil Park 《Tetrahedron》2010,66(19):3490-3498
A simple method for synthesizing several 6H-pyrrolo[1,2-c][1,2,3]triazole derivatives having a methoxycarbonyl or an acetyl group at C-5 position and 7,8-dihydro-4H-[1,2,3]triazolo[1,5-a]indol-5(6H)-ones via an intramolecular 1,3-dipolar cycloaddition reaction of azido enynes, which were readily obtained from the Morita-Baylis-Hillman acetates of propargyl aldehydes with sodium azide, has been developed. 相似文献
48.
The synthesis of diethyl β-aminovinylphosphonates 2 from acetoxy phosphonate 1 is described. The reaction entails an organocatalyzed substitution of the acetoxy group by primary or secondary amines. The use of a catalytic amount of DABCO is necessary if the amine is not nucleophilic enough, otherwise a strong nucleophilic amine can react without organocatalyst. The reaction led to a series of functionalized title compounds in good to excellent yields. 相似文献
49.
J.S. Yadav B.V. Subba Reddy Ashutosh Pratap Singh Nilanjan Majumder 《Tetrahedron letters》2010,51(17):2291-4626
Morita-Baylis-Hillman acetates undergo smooth allylic nucleophilic substitution (SN2′) with tosylmethyl isocyanide (TosMIC) in the presence of a catalytic amount of BF3·OEt2 under mild conditions to furnish trisubstituted olefins in high yields with (E)-stereoselectivity. 相似文献
50.
Stephan Schulz Andreas Kuczkowski Heidi Saxell 《Journal of organometallic chemistry》2010,695(21):2281-2283
The Lewis acid-base adduct t-Bu3Al-SbMe3 (1), which was synthesized by reaction of equimolar amounts of t-Bu3Al and trimethylstibine SbMe3, was characterized by multinuclear NMR (1H, 13C) spectroscopy, elemental analyses as well as by single crystal X-ray diffraction. 相似文献