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Intermediate ring
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Ebook "Chemical transformations of vinylidenecyclopropanes" review their investigations on the chemistry of VDCPs, mainly including the preparation, the reactivities upon treatment with Lewis or Brønsted acid, as well as transition metal catalysts and some other miscellaneous analogues. The contributions aroused a renaissance of cationic intermediates in the chemistry of VDCPs.
73p
coduathanh1122
27-03-2024
2
1
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The reaction mechanism between propadienylidene and methyleneimine was systematically investigated employing the second-order Møller–Plesset perturbation theory (MP2) method with the 6 – 31 + G* basis set. Geometry optimization, vibrational analysis, and energy property of the involved stationary points on the potential energy surface were calculated. The energies of the different species were corrected by single point energy calculations at the CCSD (T) // MP2 / 6 – 31 + G* level.
9p
langthannam
29-12-2021
15
0
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New fused tetrazolone derivatives were synthesized using homophthalic and maleic anhydrides. Treatment of anhydrides with trimethylsilyl azide opened the lactone rings and formed the corresponding intermediates, which bore 1,3-dipole and dipolarophile functionalities in ortho positions. The intermediates partially underwent internal 1,3-dipolar cycloaddition to produce fused tetrazolone derivatives. When the carbonyl groups in anhydride were not conjugated with any double bond, then a triazine-fused tetrazolone derivative was formed.
9p
langthannam
29-12-2021
14
0
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Two novel clusters of cephalosporin based on calixarene were synthesized directly or by ring expansion of the penicillin arms of calixpenams to the corresponding cephem arms via sulfoxide intermediates. Antibiotic tests showed that calixcephems have a noteworthy increase in antibacterial activity against methicillin-resistant strains of Staphylococcus aureus (MRSA) with respect to parent calixpenams and their corresponding single cephems.
9p
langthannam
29-12-2021
4
0
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In this study, nine different C-2 aroyl imidazole derivatives were synthesized in a one pot reaction with two steps, and the reduction reactions of these derivatives with NaBH4 were carried out under mild conditions. Substitution reaction of obtained imidazo methanol derivatives with chloroacetylchloride reagent and ring reaction of substitution products were investigated. It was determined that 1,4-imidazoxazinone derivative was obtained as a result of the cyclization reaction.
42p
tudichquannguyet
29-11-2021
6
1
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This paper a Buchsbaum ring R which is not Cohen-Macaulay and we construct a Cohen-Macaulay intermediate ring A ∈ Y. In order to solve the problem, we apply the method investigated by S. Goto in 1983, L. T. Nhan and M. Brodmann 2012.
6p
nguaconbaynhay12
13-06-2021
8
1
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Synthesis of 6-isomer of 5,8-O-dimethyl ether of shikonin (13), a promising anticancer scaffold, always remains a huge challenge. Herein a key intermediate for 13, 2-(1-hydroxyl-4-methyl-3-pentenyl)-1,4,5,8-tetramethoxynaphthalene (10), was obtained on the large-scale synthesis
8p
vijiraiya2711
27-05-2020
14
1
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Wehave examined the effectsof three ring-sizeanalogsof the cyclicb-sheet antimicrobial peptidegramicidinS (GS) on the thermotropic phase behavior and permeability of phos-pholipid model membranes and on the growth of the cell wall-less Gram-positive bacteriaAcholeplasma laidlawiiB. These three analogs have ring sizes of 10 (GS10), 12 (GS12) or 14 (GS14) amino acids, respectively.
10p
tumor12
22-04-2013
31
1
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GTP cyclohydrolase II catalyzes the hydrolytic release of formate and pyrophosphate from GTP producing 2,5-diamino-6-ribosylamino-4(3H)-pyrimidinone 5¢-phos-phate, the first committed intermediate in the biosynthesis of riboflavin. The enzyme was shown to contain one zinc ion per subunit. Replacement of cysteine residue 54, 65 or 67 with serine resulted in proteins devoid of bound zinc and unable to release formate fromthe imidazole ring ofGTPor from the intermediate analog, 2-amino-5-formylamino-6-ribosylamino-4(3H)-pyrimidinone 5¢-triphosphate. ...
7p
tumor12
22-04-2013
41
1
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The Na + -dependent F-ATP synthases ofIlyobacter tartaricusandPropioni-genium modestum contain membrane-embedded ring-shaped c subunit assemblies with a stoichiometry of 11. Subunit c from either organism was overexpressed in Escherichia coliusing a plasmid containing the corres-ponding gene, extracted from the membrane using detergent and then puri-fied.
10p
fptmusic
12-04-2013
35
1
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During anaerobic cobalamin (vitamin B12) biosynthesis, CbiL catalyzes methylation at the C-20 position of a cyclic tetrapyrrole ring usingS-aden-osylmethionine as a methyl group source. This methylation is a key modifi-cation for the ring contraction process, by which a porphyrin-type tetrapyrrole ring is converted to a corrin ring through elimination of the modified C-20 and direct bonding of C-1 to C-19.
11p
inspiron33
23-03-2013
35
2
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The mechanism of the ring contraction process during vitamin B12 biosyn-thesis by the anaerobe Propionibacterium shermaniiwas investigated under both aerobic and anaerobic conditions by means of feeding experiments withd-amino[1-13 C]levulinic acid (a biosynthetic intermediate of tetra-pyrrole) and d-amino[1-13 C,1,1,4-18 O3]levulinic acid in combination with 13 C-NMR spectroscopy.
7p
galaxyss3
19-03-2013
40
3
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Approximately 400-420 yds of fingering weight yarn I used Skinny Bugga by Cephalopod Yarns in Blue Ringed Octopus *Size 6 or 7 needles *Stitch markers (optional) *Blocking mat, wires, and pins *Large needle to weave in ends *Wool wash Abbreviations and Key k = knit p = purl sts = stitches ** = repeat these stitches ssk = slip, slip, knit k2tog = knit 2 together yo = yarn over pm = place marker (optional) RS = right side WS = wrong side
5p
new_would
01-03-2013
33
3
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We summarize the currently available information regarding the state of ionization and tautomerization of the 4¢-aminopyrimidine ring of the thia-mine diphosphate on enzymes requiring this coenzyme. This coenzyme forms a series of covalent intermediates with its substrates as an electro-philic catalyst, and the coenzyme itself also carries out intramolecular pro-ton transfers, which is virtually unprecedented in coenzyme chemistry.
15p
viettel02
22-02-2013
46
2
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Protein ubiquitination mediated by ubiquitin ligases plays a very important role in a wide spectrum of biological processes including development and disease pathogenesis. RING finger protein 13 (RNF13) is a recently identi-fied ubiquitin ligase which contains an N-terminal protease-associated domain and a C-terminal RING finger domain separated by a transmem-brane region.
7p
mobifone23
08-01-2013
48
3
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They stay at their table all evening. The men take it in turns to sit next to each woman and have a very quid conversation. After three minutes a bell rings and, even if you are in mid-sentence, it is time for the man to move to the next table. If you like the person you have just spoken to, you put a tick in the 'yes' box on a scorecard.
12p
kathy204
25-07-2010
93
26
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. The men take it in turns to sit next to each woman and have a very quid conversation. After three minutes a bell rings and, even if you are in mid-sentence, it is time for the man to move to the next table.
10p
kathy204
25-07-2010
78
27
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After three minutes a bell rings and, even if you are in mid-sentence, it is time for the man to move to the next table. If you like the person you have just spoken to, you put a tick in the 'yes' box on a scorecard.
10p
kathy204
25-07-2010
74
24
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The men take it in turns to sit next to each woman and have a very quid conversation. After three minutes a beli rings and, even if you are in mid-sentence, it is time for the man to move to the next table. If you like the
10p
kathy204
25-07-2010
86
29
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