NIS-promoted guanylation of amines

Ohara, Kenichi; Vasseur, Jean‐Jacques; Smietana, Michaël

doi:10.1016/j.tetlet.2009.01.073

Cited by 28 publications

(23 citation statements)

References 26 publications

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“…[ 18 F]MFBG was synthesized manually with a procedure (Figure 1) that was modified from previously published methods [13, 22]. Dry tetrabutylammonium [ 18 F]fluoride (TBA[ 18 F]F) was prepared with azeotropic evaporation under a mild flow of nitrogen [23].…”

Section: Methodsmentioning

confidence: 99%

Synthesis and evaluation of 18F-labeled benzylguanidine analogs for targeting the human norepinephrine transporter

Zhang

Huang

Pillarsetty

et al. 2013

Eur J Nucl Med Mol Imaging

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PURPOSE Both 131I- and 123I-labeled meta-iodobenzylguanidine (MIBG) have been widely used in the clinic for targeted imaging of the norepinephrine transporter (NET). The human NET (hNET) gene has been imaged successfully with 124I-MIBG PET at time points of >24 h post-injection. [18F]Fluorine-labeled MIBG analogs may be ideal to image hNET expression at time points of <8 h post-injection. We developed improved methods for the synthesis of known MIBG analogs, [18F]MFBG and [18F]PFBG and evaluated them in hNET reporter gene-transduced C6 rat glioma cells and xenografts. METHODS [18F]MFBG and [18F]PFBG were synthesized manually using a 3-step synthetic scheme. Wild-type and hNET reporter gene-transduced C6 rat glioma cells and xenografts were used to comparatively evaluate the 18F-labeled analogs with 123I/[124I]MIBG. RESULTS The fluorination efficacy on benzonitrile was predominantly determined by the position of the trimethylammonium group. The para-isomer afforded higher yields (75±7%) than meta-isomer (21±5%). The reaction of [18F]fluorobenzylamine with 1H–pyrazole-1-carboximidamide was more efficient than with 2-methyl-2-thiopseudourea. The overall radiochemical yields (decay-corrected) were 11±2% (n = 12) for [18F]MFBG, and 41±12% (n = 5) for [18F]PFBG, respectively. The specific uptakes of [18F]MFBG and [18F]PFBG were similar in C6-hNET cells, but 4-fold less than that of 123I/[124I]MIBG. However, in vivo [18F]MFBG accumulation in C6-hNET tumors was 1.6-fold higher than that of [18F]PFBG at 1 h p.i., whereas their uptakes were similar at 4 h. Despite [18F]MFBG having a 2.8-fold lower affinity to hNET and approximately 4-fold lower cell uptake in vitro compared to 123I/[124I]MIBG, PET imaging demonstrated that [18F]MFBG was able to visualize C6-hNET xenografts better than [124I]MIBG. Biodistribution studies showed [18F]MFBG and 123I-MIBG had a similar tumor accumulation, which was lower than that of no-carrier-added [124I]MIBG; but [18F]MFBG showed a significantly more rapid body clearance and lower uptake in most non-targeting organs. CONCLUSION [18F]MFBG and [18F]PFBG were synthesized in reasonable radiochemical yields under milder conditions. [18F]MFBG is a better PET ligand to image hNET expression in vivo at 1 to 4 h post injection, than both [18F]PFBG and 123I/[124I]MIBG.

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Section: Methodsmentioning

confidence: 99%

Synthesis and evaluation of 18F-labeled benzylguanidine analogs for targeting the human norepinephrine transporter

Zhang

Huang

Pillarsetty

et al. 2013

Eur J Nucl Med Mol Imaging

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“…Lewis acid, and thus coordinate the protected thio and S-methylisothioureas also adding Et 3 N. [63] Yeung et al in 2011 developed, a general and efficient one-pot guanidine synthesis using an olefin, NBS, an amide, and a cyanimide (Scheme 41.). A wide range of guanidine derivatives could be synthesized using this methodology.…”

Section: From Substituted Methaniminesmentioning

confidence: 99%

Guanidines from ‘toxic substances’ to compounds with multiple biological applications – Detailed outlook on synthetic procedures employed for the synthesis of guanidines

Tahir

Badshah

Hussain

2015

Bioorganic Chemistry

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“…In the case of guanidinylation of resin‐bound amines using di‐Boc‐protected thiourea 6 under Mukaiyama's conditions, the reaction efficacy depends on the steric hindrance of the amino group and the solvent . In addition, reaction of resin‐bound amine may react with Mukaiyama's reagent 7 , or reaction with thiourea 6 via S‐atom may result in corresponding S ‐aminoisothiourea . Our experience concerning the solid‐phase guanidinylation of amino‐precursors for fusaricidin/LI‐F analogs synthesis using 5 mirrors published results, whereas use of 6 under Mukaiyama's reaction conditions afforded inconsistent yields and purities of the desired products .…”

Section: Introductionmentioning

confidence: 99%

Solid‐phase synthesis of fusaricidin/li‐f class of cyclic lipopeptides: Guanidinylation of resin‐bound peptidyl amines

2013

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Fusaricidins/LI-Fs and related cyclic lipopeptides represent an interesting new class of antibacterial peptides with the potential to meet the challenge of antibiotic resistance in bacteria. Our previous study (N. Bionda et al. ChemMedChem 2012, 7, 871-882) revealed the significance of the guanidinium group located at the termini of the lipidic tails of these cyclic lipopeptides for their antibacterial activities. Therefore, devising a synthetic strategy that will allow incorporation of guanidinium functionality into their structure is of particular practical importance. Since appropriately protected guanidino fatty acid building blocks are not commercially available, our strategy toward guanidinylated fusaricidin/LI-F analogs include solid-phase synthesis of a cyclic lipopeptide precursor possessing a lipidic tail with a terminal amino group followed by its conversion into corresponding guanidine. To find the optimal method for this conversion, we have examined commonly used guanidinylation reagents under the conditions compatible with standard solid-phase peptide synthesis. Described experimental results demonstrated superiority of N,N′-di-Boc-N″-triflylguanidine in solid-phase preparation of fusaricidin/LI-F class of cyclic lipopeptides. The triflylguanidine reagent gave a single monoguanidinylated product in excellent yield independently of the type of solid-support.

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NIS-promoted guanylation of amines

Cited by 28 publications

References 26 publications

Synthesis and evaluation of 18F-labeled benzylguanidine analogs for targeting the human norepinephrine transporter

Synthesis and evaluation of 18F-labeled benzylguanidine analogs for targeting the human norepinephrine transporter

Guanidines from ‘toxic substances’ to compounds with multiple biological applications – Detailed outlook on synthetic procedures employed for the synthesis of guanidines

Solid‐phase synthesis of fusaricidin/li‐f class of cyclic lipopeptides: Guanidinylation of resin‐bound peptidyl amines

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