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1.
An efficient three-step synthesis of 2-halo-3-aryl-4(3H)-quinazoliniminium halides from commercially available materials is described. Upon reaction with hydrogen halides, generated in situ from a Lewis acid (MX) and trace water, a variety of easily accessible heteroenyne-allenes underwent facile intramolecular cyclization to afford the title compounds in good yields. The method is highly versatile and provides a general way to construct quinazoliniminium ring systems with a variety of different substitutions. 相似文献
2.
The homoallyl cation formed from a cyclopropyl carbinol that was vicinally substituted by a silylmethyl function underwent smooth Prins cyclization with aldehydes and ketones to form 2,4,6-trisubstituted tetrahydropyrans with very high stereoselectivity. 相似文献
3.
A Gurtu P K Malhotra I S Mittra P M Sood SC Gupta VK Gupta GL Kaul LK Mangotra Y Prakash NK Rao ML Sharma 《Pramana》1974,3(5):311-322
This is a continuation of our earlier investigation (Gurtuet al 1974Phys. Lett. 50 B 391) on multiparticle production in proton-nucleus collisions based on an exposure of emulsion stack to 200 GeV/c beam at the NAL. It is found that the ratioR em = 〈n s〉/〈n ch〉, where 〈n ch〉 is the charged particle multiplicity in pp-collisions, increases slowly from about 1 at 10 GeV/c to 1·6 at 68 GeV/c and attains a constant value of 1·71 ± 0·04 in the region 200 to 8000 GeV/c. Furthermore,R em = 1·71 implies an effectiveA-dependence ofR A =A 0.18,i.e., a very weak dependence. Predictions ofR em on various models are discussed and compared with the emulsion data. Data seem to favour models of hadron-nucleon collisions in which production of particles takes place through adouble step mechanism,e.g., diffractive excitation, hydrodynamical and energy flux cascade as opposed to models which envisage instantaneous production. 相似文献
4.
Heteroaryl 2-silylmethyl-substituted cyclopropyl ketones rearrange under Lewis acid conditions via heteroaromatic homo-Nazarov cyclization to form 2,3-heteroaromatic ring fused 4-t-butyldiphenylsilylmethyl-substituted cyclohexanones. 相似文献
5.
The eigen frequencies of radial pulsations of neutron stars are calculated in a strong magnetic field. At low densities we
use the magnetic BPS equation of state (EOS) similar to that obtained by Lai and Shapiro while at high densities the EOS obtained
from the relativistic nuclear mean field theory is taken and extended to include strong magnetic field. It is found that magnetized
neutron stars support higher maximum mass whereas the effect of magnetic field on radial stability for observed neutron star
masses is minimal. 相似文献
6.
Munshi G Mustafa Sudhir Raniwala T Awes B Rai RS Bhalerao JG Contreras RV Gavai SK Ghosh P Jaikumar GC Mishra AP Mishra H Mishra B Mohanty J Nayak J-Y Ollitrault SC Phatak L Ramello R Ray PK Sahu AM Srivastava DK Srivastava VK Tiwari 《Pramana》2006,67(5):961-981
This is the report of Heavy Ion Physics and Quark-Gluon Plasma at WHEPP-09 which was part of Working Group-4. Discussion and
work on some aspects of quark-gluon plasma believed to have created in heavy-ion collisions and in early Universe are reported. 相似文献
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8.
The combination of homo-Nazarov cyclization of 2-(tert-butyldiphenylsilylmethyl)cyclopropyl vinyl ketone leading to oxyallyl cation and its subsequent [3+2] capture by allylsilane has been demonstrated as an useful strategy for the construction of functionalized bicyclo[3.2.1]octan-8-ones. The [3+2] capture proceeds exclusively in the exo mode to make the overall reaction diastereoselective. The less substituted end of the oxyallyl cation was found to react nearly two times faster than the more substituted end. 相似文献
9.
Vicinal silylmethyl-substituted cyclopropyl carbinols undergo tandem intermolecular cation-arylacetylene cyclization to generate indene derivatives. 相似文献
10.
Ce0.8Eu0.2O2?δ was synthesized by conventional solid state route as well as wet chemical route (i.e. cation complexation, combustion method). The crystallite size obtained for cation complexation and combustion samples is 14 and 19 nm while their surface area is 11.70 and 29.63 m2g?1 respectively. Cation complexation synthesized product lead to formation of agglomerates and hence the sintered sample showed porosity compared to combustion synthesized sample. However, despite high packing density the combustion synthesized sample showed lower grain boundary, total conductivity than cation complexation synthesized product due to the formation of siliceous film at the grain boundary. 相似文献