Preparation of chiral phosphorus, sulfur and selenium containing 2-aryloxazolines
作者:Markus Peer、Johannes C. de Jong、Matthias Kiefer、Thomas Langer、Heiko Rieck、Heico Schell、Peter Sennhenn、Jürgen Sprinz、Henning Steinhagen、Burkhard Wiese、Günter Helmchen
DOI:10.1016/0040-4020(96)00267-0
日期:1996.5
synthetic amino alcohols. For oxazoline formation three procedures were employed: (i) one pot condensation with a 2-halobenzoic acid, (ii) ZnCl2 catalyzed condensation with a 2-halobenzonit-rile, and (iii) a three step sequence via a 2-halobenzamide and a tosylate or chloride. Phosphinooxazolines containing stereogenic phosphorus were prepared by either diastereoselective nucleophilicsubstitution of halogenide
由市售或合成的氨基醇制备一系列对映体纯的2- [2-(二芳基膦基)芳基]-恶唑啉。对于恶唑啉的形成,采用了三种程序:(i)与2-卤代苯甲酸一锅缩合,(ii)ZnCl 2与2-卤代苯甲腈-苯胺催化缩合,和(iii)通过2-卤代苯甲酰胺的三步顺序和甲苯磺酸盐或氯化物。通过非对映选择性亲核取代Ar 1 Ar 2 PC1的卤化物或通过LiPAr 1 Ar 2亲核芳族取代制备含有立体异构磷的膦恶唑啉。另外,制备了硫和硒类似物。
Total Synthesis of (+)-Manzamine A
作者:Tatsuya Toma、Yoichi Kita、Tohru Fukuyama
DOI:10.1021/ja103721s
日期:2010.8.4
A novel synthetic route to (+)-manzamine A was developed. It highlights an amazingly efficientconstruction of a highly strained 15-membered ring across a cyclohexenone ring with the aim of installing the requisite functionalities in a completely stereocontrolled manner. Other key features include a stereoselective Diels-Alder reaction of an optically active butenolide, construction of the 15-membered
作者:J.B. Sweeney、Alan F. Haughan、J.R. Knight、Smita Thobhani
DOI:10.1016/j.tet.2006.12.035
日期:2007.3
In contrast to the corresponding hydroxyiodination reactions, the reaction of acetoxycyclohex-2-ene 1 with N-PSP in the presence of water shows little regiocontrol, but is highly diastereoselective. However, the same reaction of the (R)-phenylglycinate derivative of (±)-cyclohexen-3-ol is highly diastereoselective, and regioselective. A hydrogen-bonding interaction is proposed to rationalize these
Development of new simple molecular probes of DNA bulged structures
作者:Ziwei Xiao、Lizzy S. Kappen、Irving H. Goldberg
DOI:10.1016/j.bmcl.2006.03.006
日期:2006.6
NCSi-gb is a neocarzinostatin chromophore (NCS-chrom) metabolite which binds strongly to certain two-base DNA bulges. Compared with previously reported NCSi-gb analogues, a new analogue with a different aminoglycoside position was synthesized, and it showed strong fluorescence and improved binding and sequence selectivity to DNA bulges. The N-dimethylated form of this analogue had a similar binding
In a series of studies on structure-activity relationships of 2-substituted 19-norvitamin D analogs, we found that 1 alpha,25-dihydroxy-19-norvitamin D-3 analogs with 2 beta-hydroxyethoxy or 2E-hydroxyethylidene moieties show strong binding affinity for the vitamin D receptor (VDR) as well as marked transcriptional activity. To further examine the effects of side chain structure on the activity of 2-substituted 19-norvitamin D analogs, we have synthesized new 19-norvitamin D3 analogs with modifications in both the A-ring at the C(2) position and the side chain. The side chains of these analogs contained a double bond between C(22) and C(23) or an oxygen atom at C(22). The biological activity of the analogs was evaluated in vitro. All the side chain-modified analogs were less active than 1 alpha,25-dihydroxyvitamin D-3 1e and the parent compounds 3-6e possessing a natural 20R-configuration in binding to the VDR, but, except for the (20R)-22-oxa analogs 3-6d, were significantly more potent in transcriptional activity. Of the side-chain-modified analogs 4 and 5, the 2 beta-hydroxyethoxy- and 2E-hydroxyethylidene-22,24-diene-24a,26a,27a-trihorno analogs showed markedly higher transcriptional activity (25- and 17.5-fold, respectively) compared with le. Elongation of the side chain at the C-24, C-26, and C-27 positions and introduction of a 22,24-diene moiety strongly increased transcriptional activity, as seen in the 20-epi analogs 3-6f. (c) 2006 Elsevier Ltd. All rights reserved.