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31.
We have recently described an efficient preparation of ketones (or esters) from organomanganous iodides (RMnI) and acid chlorides2 (or chloro-carbonates3). The scope of this reaction is very large and RMnI is often superior to other organometallics. However, the major limitations of this reaction are2b: 相似文献
32.
Suely L. Galdino Maria C. A. Lima Alexandre J. S. Góes Ivan R. Pitta Cuong Luu-Duc 《光谱学快报》2013,46(7-8):1013-1021
In the present investigation, a study of the electron impact mass spectrometry data is reported for seven compounds of a series of some 3-(4-chlorobenzyl)-5-benzylidene-imidazolidine-2, 4-diones and 3-(4-fluoro or chlorobenzyl)-5-benzylidene-thiazolidine-2, 4-diones previously synthesized. 相似文献
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In this paper we report a simple methodology for obtaining (+) trans - 1,2 - epoxylimonene (1b) in high purity (>99% HRGC) and reasonable quantity. The mixture of 1a and 1b in CH2Cl2 is stirred with 1M NaHSO3 in water. Under these conditions 1a is completely destroyed, while 1b is only partially destroyed. 相似文献
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Andrea Paesano Jr. Alexandre Christófaro Silva Flávio Francisco Ivashita Carla Fabiana Cerqueira Machado-Flavio Sives Flávio Sives Roberto Carlos Mercader José Domingos Fabris 《Hyperfine Interactions》2014,226(1-3):585-592
A peatland in Pinheiro, Diamantina City, Minas Gerais State - Brazil, was sampled at different depths of two profiles with diverse vegetation coverings (grassland field and bush) in order to collect materials that might reflect changes in the chemical states of iron over the peat formation coming from original minerals such as hematitic phyllite surrounding the boggy pedon. Samples collected were chemically, structurally and magnetically characterized. The results show that both series of peats are composed of organic matter and minerals such as quartz, kaolinite, gibbsite, rutile and muscovite. Deeper layers present only quartz. Mössbauer spectroscopy shows that iron is present in both electron states, Fe2+ and Fe3+, under both vegetations, each valence appearing in the spectra in the form of a discrete doublet. No hyperfine magnetic splitting was observed in any spectrum at room temperature. The Mössbauer subspectral area of Fe2+ tended to increase from the upper to deeper layers. Magnetic measurements reveal that the magnetic response of the surface samples is the highest, displaying a sharp decrease below 15 cm and that the magnetic signal is a superposition of (super)paramagnetic and ferrimagnetic contributions. Samples from the grassland field also show a diamagnetic component for the deeper layers. 相似文献
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Xu‐Wen Li Alexandre Ear Lukas Roger Dr. Nassima Riache Alexandre Deville Dr. Bastien Nay 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(48):16389-16393
A bio‐inspired strategy was used to complete the formal synthesis of the antitubercular hirsutellone B and congeners A and C, through construction of its decahydrofluorene core from a linear polyene strand activated at both ends by a silyl enol ether and an allyl acetate. Our synthesis features a key electrophilic cyclization, starting with the remote activation (by [Yb(OTf)3] or BF3 ? OEt2) of the allyl acetate and stereoselectively affording the C ring. This was followed by an intramolecular Diels–Alder reaction to get the tricyclic core of the natural product. The stereoselective reduction of the resulting ketone towards the formal intermediate was critical to the success of this strategy. 相似文献
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