Synthesis of saturated fatty acids 11C(13C)-labelled in the ω-methyl position
摘要:
A method for the preparation of saturated fatty acids C-11 (C-13)-labelled in the omega-methyl position is described. A highly reactive zerovalent copper complex was prepared from lithium naphtalenide reduced lithium(2-thienyl)iodocuprate. The labelling precursors were obtained by addition of tert-butyl omega-iodocarboxylates to the organocuprate and these were reacted with [C-11]methyl iodide to form C-11-labelled.
Neu, H.; Kihlberg, T.; Langstroem, B., Journal of labelled compounds and radiopharmaceuticals, 1997, vol. 40, p. 796 - 797
作者:Neu, H.、Kihlberg, T.、Langstroem, B.
DOI:——
日期:——
Chirospecific Syntheses of Precursors of Cyclopentane and Cyclopentene Carbocyclic Nucleosides by [3 + 3]-Coupling and Transannular Alkylation
作者:Jeffrey A. Campbell、Won Koo Lee、Henry Rapoport
DOI:10.1021/jo00119a044
日期:1995.7
A new method is reported for the preparation of enantiomerically pure (1R,2S,4S)-1-amino-2-hydroxy-4-(hydroxymethyl)cyclopentane, (1R,2R,4S)-1-amino-2-fluoro-4-(hydroxymethyl)cyclopentane, and (1R,4S)-1-amino-4-(hydroxymethyl)-2-cyclopentene, advanced precursors to carbocyclic nucleosides. The method involves initial conversion of D-serine into an aldehyde with 9-phenylfluorenyl protection at nitrogen and O-benzyl protection at oxygen. A [3 + 3]-coupling of this aldehyde with a titanium homoenolate derived from tert-butyl 3-iodopropionate gave the corresponding anti-lactone in high yield. Regioselective hydrogenolysis of the amine protecting group, accompanied by intramolecular O- to N-cyclization formed a lactam. After suitable nitrogen protection and functional group manipulation, transannular alkylation afforded the corresponding 2-benzyl- or 2-(p-methoxybenzyl)-6-hydroxy-2-azabicycclo[2.2.1]-3-heptanone. Functional group modification of the 2-benzyl analogue gave the resulting 6(S)-hydroxy and 6(R)-fluoro N-BOC imides; alternatively, the 2-(p-methoxybenzyl) analogue was converted to an N-BOC imide containing an olefinic Linkage at C-5 and C-6 of the bicycle. Subjecting each of the N-BOC imides to a reduction-deprotection sequence then afforded the desired carbocyclic analogues. The [3 + 3]-coupling method also allowed improved and expedient access to an advanced tribenzylated lactam previously used in the racemic syntheses of the hydroxylated alkaloids D-mannonolactam, deoxymannojirimycin, and prosopinone, providing a formal asymmetric synthesis of these alkaloids.
MAGNETIC GAS SENSOR AND METHODS USING ANTIFERROMAGNETIC HEMATITE NANOPARTICLES
申请人:PUNNOOSE ALEX
公开号:US20090133473A1
公开(公告)日:2009-05-28
A nanoscale antiferromagnetic gas sensing apparatus and methods of measuring gas using the apparatus are described. The use of the magnetic properties of an antiferromagnetic material as gas sensing parameters explores the concept of magnetic gas sensing. According to a preferred embodiment, a nanoscale magnetic hydrogen sensor apparatus is developed based on varying of the saturation magnetization and remanence of nanoscale antiferromagnetic hematite with hydrogen flow. For example, the saturation magnetization and remanence of nanoscale hematite has been shown to increase one to two orders of magnitude in the presence of flowing hydrogen gas at concentrations in the 1-10% range and at 575 K, indicating that a magnetic hydrogen sensor using hematite material may be practical and useful for detecting hydrogen in various environments such as those wherein production, storage, transportation, and/or vehicle use of hydrogen is being conducted.
Substituted Cyclodextrin Derivatives Useful As Intermediates For Producing Biologically Active Materials
申请人:Van Calenbergh Serge
公开号:US20130046087A1
公开(公告)日:2013-02-21
The present invention relates to substituted cyclodextrin derivatives which are particularly useful intermediates for producing well-defined carboxyalkylated cyclodextrins in contrast with the poorly-defined mixtures available through prior art procedures. The present invention also relates to processes for their preparation in a limited number of steps. These well-defined carboxyalkylated cyclodextrins can be polysulfated according to procedures standard in the art and some of these polysulfates, and alkali salts thereof, have been found to exhibit biologically active properties especially for the treatment and/or prophylaxis of degenerative joint diseases (e.g. osteoarthritis) or heparin-induced thrombocytopenia, or for cartilage repair or connective tissue repair.