- Organocatalytic Chlorination of Alcohols by P(III)/P(V) Redox Cycling
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A catalytic system for the chlorination of alcohols under Appel conditions was developed. Benzotrichloride is used as a cheap and readily available chlorinating agent in combination with trioctylphosphane as the catalyst and phenylsilane as the terminal reductant. The reaction has several advantages over other variants of the Appel reaction, e.g., no additional solvent is required and the phosphane reagent is used only in catalytic amounts. In total, 27 different primary, secondary, and tertiary alkyl chlorides were synthesized in yields up to 95%. Under optimized conditions, it was also possible to convert epoxides and an oxetane to the dichlorinated products.
- Longwitz, Lars,Jopp, Stefan,Werner, Thomas
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p. 7863 - 7870
(2019/06/27)
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- Hypervalent Iodine-Based Activation of Triphenylphosphine for the Functionalization of Alcohols
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The use of hypervalent iodine reagents as a general tool for the activation of PPh 3 and its application to the functionalization of alcohols is reported. Combination of PPh 3 with PhICl 2 or TolIF 2 gives dihalophosphoranes that are characterized by 31 P NMR, however, with PhIOAc 2, PhI(OTFA) 2, or the cyclic chloro(benzoyloxy)iodane, no phosphoranes were observed. Reaction of these iodanes with PPh 3 in the presence of primary, secondary, or tertiary alcohols results in either halogenation or acyl-transfer products in moderate to high yield.
- Eljo, Jasmin,Carle, Myriam S.,Murphy, Graham K.
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supporting information
p. 2871 - 2875
(2017/10/06)
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- HETEROCYCLIC SUBSTITUTED PIPERAZINES FOR THE TREATMENT OF SCHIZOPHRENIA
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This invention relates to compounds of the formula 1 wherein X, Y, Z, A, R', R2, R3, R4, R9, W' and W2 are defined as in the specification, pharmaceutical compositions containing them and their use in the treatment of central nervous system and other diso
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Page 132; 133
(2010/02/06)
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- 7-Substituted 5-amino-2-(2-furyl)pyrazolo[4,3-e]-1,2,4-triazolo[1,5-c]pyrimidines as A2A adenosine receptor antagonists: A study on the importance of modifications at the side chain on the activity and solubility
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It was demonstrated in the early 1990s that adenosine exerts many physiological functions through the interaction with four different receptors, named A1, A2A, A2B, and A3. In the past few years, our group has been involved in the development of A2A antagonists, which led to the synthesis of SCH 58261 (1), the first potent and selective adenosine A2A antagonist, which has been widely used as a reference compound. In this paper, we present an extended series of pyrazolotriazolopyrimidines synthesized with the aim to investigate the influence of the substitutions on the pyrazole ring. The choice of the substituents was based on their capability to improve water solubility while retaining high affinity and selectivity at the human A2A adenosine receptor subtype. In this series, some structural characteristics that are important for activity, i.e., tricyclic structure, free amino group at 5-position, furan ring, and substituent at 7-position on the pyrazole moiety, have been maintained. We focused our attention on the nature of the phenyl ring substituent to improve water solubility. Following this strategy, we developed new compounds with good affinity and selectivity for A2A adenosine receptors, such as 8d (Ki 0.12 nM; hA1/hA2A ratio = 1025; Rm = 2.8), 8h (Ki 0.22; hA1/hA2A ratio = 9818; Rm = 3.4), 8i (Ki 0.18 nM; hA1/hA2A ratio = 994; Rm = 2.8), 8k (Ki 0.13 nM; hA1/hA2A ratio = 4430; Rm = 3.6), and 14b (Ki 0.19 nM; hA1/hA2A ratio = 2273; Rm = 2.7). All the new synthesized compounds have no significant interaction with either A2B or A3 receptor subtypes. This new series of compounds deeply enlightens some structural requirements to display high affinity and selectivity for the A2A adenosine receptor subtype, although our goal of identifying new compounds with increased water solubility was not completely achieved. On this basis, other strategies will be devised to improve this class of compounds with a profile that appears to be promising for treatment of neurodegenerative disorders, such as Parkinson's disease.
- Baraldi,Cacciari,Romagnoli,Spalluto,Monopoli,Ongini,Varani,Borea
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p. 115 - 126
(2007/10/03)
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- Nucleotides. Part XL. Synthesis and characterization of modified 2'-5' adenylate trimers - Potential antiviral agents
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2'-5' Adenylate trimers 41-44 carrying the (tert-butyl)dimethylsilyl (tbds) group at the 3'-OH position of various sugar moieties were synthesized via the phosphoramidite method. The use of the (tert-butyloxy)carbony (boc) and (2-(4-nitrophenyl)ethylsulfo
- Schirmeister,Pfleiderer
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- The 2-Dansylethoxycarbonyl (=2-{[5-dimethylamino)naphthalen-1-yl]sulfonyl}ethoxycarbonyl; Dnseoc) group for protection of the 5'-hydroxy function in oligodeoxyribonucleotide synthesis
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Use of the 2-dansylethoxycarbonyl (=2-{[5-(dimethylamino)naphthalen-1-yl]sulfonyl])ethoxycarbonyl; Dnseoc) group as an intermediate 5'-OH protecting group in oligodeoxyribonucleotide synthesis using the automated phosphoramidite approach is described in a model study to an alternative strategy in RNA synthesis.
- Bergmann,Pfleiderer
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p. 203 - 215
(2007/10/02)
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- SYNTHESIS OF O4-p-NITROPHENYLETHYL THYMIDINE AND URIDINE DERIVATIVES
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O4-Protection in thymidine and uridine derivatives has been achieved by the p-nitro-phenylethyl group in a silver-ion catalysed alkylation reaction to form valuable building blocks for oligonucleotides syntheses.
- Schulz, Bernd S.,Pfleiderer, Wolfgang
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p. 3587 - 3590
(2007/10/02)
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