- Development of pH-activatable fluorescent probes for rapid visualization of metastatic tumours and fluorescence-guided surgeryviatopical spraying
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A series of pH-activatable aza-BODIPY-based fluorescent probes were developed for rapid cancer visualization and real-time fluorescence-guided surgery by harnessing topical spraying. These probes exhibited good water-solubility, a tunable pKafrom 5.0 to 7.9, and stable intense NIR emission at ~725 nm under acidic conditions.AzaB5with a pKavalue of 6.7 was able to rapidly and clearly visualize pulmonary and abdominal metastatic tumours including tiny metastases less than 2 mmviatopical spraying, further improving intraoperative fluorescence-guided resection. We believe thatAzaB5is promising as a powerful tool to rapidly delineate a broad range of malignancies and assist surgical tumour resection.
- Cao, Wenwen,Li, Xiaoxin,Wu, Peng,Xiong, Hu
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supporting information
p. 10636 - 10639
(2021/10/19)
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- Transfer of a positively charged acyl group between substituted phenolate ion nucleophiles: The Bronsted β for the calibrating equilibrium for N-methylisonicotinyl (4-carbonyl-N-methylpyridinium) transfer
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Rate constants have been measured for the reaction of substituted phenolate ions with aryl acetate esters and with aryl N-methylisonicotinate esters? in aqueous solution. A new method is demonstrated for determining βeq for group transfer from 4-nitrophenyl esters; it employs the rate constant for the reaction of 2,6-difluorophenolate ion with substituted phenyl ester as a surrogate for the reactivity of the 4-nitrophenolate ion and yields βeq = 1.55 for the N-methylisonicotinyl transfer reaction. The Bronsted-type plot of the rate constant for phenolate ion attack on 4-nitrophenyl N-methylisonicotinate is linear over a range of pKa values from 5.5 to 10 and provides good evidence for a concerted displacement mechanism for this reaction. The reactivity of the N-methylisonicorinate esters to phenolate ions is some 300 times larger than that of the corresponding acetate esters but the larger βnuc value (0.90 compared with 0.74) suggests a 'later' transition structure. Calibration of the β values with the corresponding βeq gives a Leffler αnuc = 0.58 and 0.42 for N-methylisonicotinate and acetate respectively, which contrasts with the order expected from reactivity-selectivity. The tighter transition structure indicated by comparison of these α values is explained by a less favourable acylium ion in the case of the N-methylisonicotinyl transfer reaction.
- Colthurst, Matthew J.,Nanni, Matilde,Williams, Andrew
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p. 2285 - 2291
(2007/10/03)
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- Synthesis of pentafluorobenzyloxy mono- to tetrafluoroacetophenones
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Pentafluorobenzyloxyacetophenones are formed by reacting 2',3',4',5',6'-pentafluoroacetophenone and 2',3',4',5'-tetrafluoroacetophenone with pentafluorobenzyl alcohol (PFBA) in refluxing toluene under phase-transfer conditions.This provided seven new such
- Xu, Linxiao,Giese, Roger W.
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- UNUSUAL REACTIVITY OF PENTAFLUOROBENZYL AROMATIC ETHERS UNDER FRIEDEL-CRAFTS REACTION CONDITIONS
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A pentafluorobenzyl (PFBz) ether of 2,6-dimethylphenol undergoes a PFBz rearrangement, which appears to be intermolecular, yielding a 2:3 ratio of meta to para migration.Only ether bond cleavage takes place in a corresponding PFBz ether of 2,6-difluorophenol.Both sets of products are unusual, and it is suggested that they are both due to high reactivity of the PFBz-oxy moiety with the AlCl3 catalyst.
- Xu, Linxiao,Giese, Roger W.
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p. 3829 - 3832
(2007/10/02)
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- Structure-reactivity correlations for reactions of substituted phenolate anions with acetate and formate esters
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The reactions of substituted phenolate anions with m-nitrophenyl, p-nitrophenyl, and 3,4-dinitrophenyl formates follow nonlinear Br?nsted-type correlations that might be taken as evidence for a change in the rate-limiting step of a reaction that proceeds through a tetrahedral addition intermediate. However, the correlation actually represents two different Br?nsted lines that are defined by meta- and para-substituted phenolate anions and by meta- and para-substituted o-chlorophenolate anions. A concerted mechanism for both acetyl- and formyl-transfer reactions is supported by the absence of a detectable change in the Br?nsted slope at ΔpK = 0 for the attacking and leaving phenolate anions within each class of Br?nsted correlations. Regular increases in the dependence of log k on the pKa of the nucleophile with increasing pKa of the leaving group correspond to a positive interaction coefficient pxy = ?β1g/?(pKnuc) = ?βnuc/?(pK1g). The observation of two different Br?nsted lines for the reactions of substituted phenolate anions with phenyl acetates is attributed to a steric effect that decreases the rate of reaction of substituted o-chlorophenolate anions by 25-50%. The reactions of meta- and para-substituted phenolate and o-chlorophenolate anions with substituted phenyl acetate esters follow values of βnuc = 0.53-0.66 and -β1g = 0.50-0.63. The reactions of meta- and para-substituted phenolate anions with formate esters are ~ 103 times faster and follow smaller values of βnuc = 0.43-0.64 and -β1g = 0.31-0.48. However, the reactions of meta- and para-substituted o-chlorophenolate anions with the same formate esters follow larger values of βnuc = 0.63-0.90 and -β1g = 0.46-0.90. The large values of βnuc and -β1g for the reactions of substituted o-chlorophenolate anions with formate esters may arise from destabilization by the o-chloro group of a stacking interaction that is present in the transition state for reactions of formate esters, but not acetate esters.
- Stefanidis, Dimitrios,Cho, Sayeon,Dhe-Paganon, Sirano,Jencks, William P.
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p. 1650 - 1656
(2007/10/02)
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