A simple method for C-6 modification of guanine nucleosides

Lakshman, Mahesh K.; Frank, Josh

doi:10.1039/b905298d

Cited by 31 publications

(57 citation statements)

References 24 publications

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“…Some authors use firm-level, rather than BOP-initiative-level, measures to assess profitability. Lakshman (2009), for instance, cites a 30% increase in market capitalization for ITC Ltd as its focus on BOP markets grows.…”

Section: Outcomes Of Bop Initiativesmentioning

confidence: 99%

Reviewing a Decade of Research on the “Base/Bottom of the Pyramid” (BOP) Concept

2013

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In 1998-1999, Prahalad and colleagues introduced the base/bottom of the pyramid (BOP) concept in an article and a working paper. This article’s goal is to answer the following question: What has become of the concept over the decade following its first systematic exposition in 1999? To answer this question, the authors conducted a systematic review of articles on the BOP, identifying 104 articles published in journals or proceedings over a 10-year period (2000-2009). This count excludes books, chapters, and teaching cases. The review shows that the BOP concept evolved dramatically following Prahalad’s original call to multinational enterprises (MNEs). Deemphasizing the role of MNEs over time, published BOP articles portray a more complex picture, with wide variations in terms of BOP contexts, of BOP initiatives, and of impacts of the BOP approach. A simple framework for organizing the reviewed articles helps discuss findings, identify the gaps that still exist in the literature, and suggest directions for future research.

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Section: Outcomes Of Bop Initiativesmentioning

confidence: 99%

Reviewing a Decade of Research on the “Base/Bottom of the Pyramid” (BOP) Concept

2013

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“…Syntheses of compounds 1 , 4 , 7 , and 8 have been published previously, 11,15 and compounds 9 – 14 were synthesized via analogous procedures.…”

Section: Resultsmentioning

confidence: 99%

“…Conversion of O 6 -(benzotriazol-1-yl)guanosine derivative 7 to the O 6 -allyl compound 15 was accomplished as described. 15 Diazotization-bromination then gave the 2-bromo- O 6 -allyl guanosine derivative 16 . 25 Notably, when this reaction was conducted in CH 2 Cl 2 a minor byproduct ( 17 ) was observed that was consistent with the allyl group dibromination, on the basis of 1 H NMR and HRMS analysis.…”

Section: Resultsmentioning

confidence: 99%

A novel bis(pinacolato)diboron-mediated N–O bond deoxygenative route to C6 benzotriazolyl purine nucleoside derivatives

et al. 2016

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Reaction of amide bonds in t-butyldimethylsilyl-protected inosine, 2′-deoxyinosine, guanosine, 2′-deoxyguanosine, and 2-phenylinosine with commercially available peptide-coupling agents (benzotriazol-1H-yloxy)tris(dimethylaminophosphonium) hexafluorophosphate (BOP), (6-chloro-benzotriazol-1H-yloxy)trispyrrolidinophosphonium hexafluorophosphate (PyClocK), and (7-azabenzotriazol-1H-yloxy)trispyrrolidinophosphonium hexafluorophospate (PyAOP) gave the corresponding O6-(benzotriazol-1-yl) nucleoside analogues containing a C–O–N bond. Upon exposure to bis(pinacolato)diboron and base, the O6-(benzotriazol-1-yl) and O6-(6-chlorobenzotriazol-1-yl) purine nucleoside derivatives obtained from BOP and PyClocK, respectively, underwent N–O bond reduction and C–N bond formation, leading to the corresponding C6 benzotriazolyl purine nucleoside analogues. In contrast, the 7-azabenzotriazolyloxy purine nucleoside derivatives did not undergo efficient deoxygenation, but gave unsymmetrical nucleoside dimers instead. This is consistent with a prior report on the slow reduction of 1-hydroxy-1H-4-aza and 1-hydroxy-1H-7-azabenzotriazoles. Because of the limited number of commercial benzotriazole-based peptide coupling agents, and to show applicability of the method when such coupling agents are unavailable, 1-hydroxy-1H-5,6-dichlorobenzotriazole was synthesized. Using this compound, silyl-protected inosine and 2′-deoxyinosine were converted to the O6-(5,6-dichlorobenzotriazol-1-yl) derivatives via in situ amide activation with PyBroP. The O6-(5,6-dichlorobenzotriazol-1-yl) purine nucleosides so obtained also underwent smooth reduction to afford the corresponding C6 5,6-dichlorobenzotriazolyl purine nucleoside derivatives. A total of 13 examples were studied with successful reactions occurring in 11 cases (the azabenzotriazole derivatives, mentioned above, being the only unreactive entities). To understand whether these reactions are intra or intermolecular processes, a crossover experiment was conducted. The results of this experiment as well as those from reactions conducted in the absence of bis(pinacolato)diboron and in the presence of water indicate that detachment of the benzotriazoloxy group from the nucleoside likely occurs, followed by reduction, and reattachment of the ensuing benzotriazole, leading to products.

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“…The authors were surprised to find that electron transfer was more efficient in duplexes containing a mismatch, possibly because the mismatch site enables electron injection or hopping beyond this site. Synthetic methods of relevance to DNA and RNA chemistry continue to be developed (Lakshman & Frank, 2009, Kaloudis et al, 2009, Edwards et al, 2009& Ohkubo et al, 2009). The chemical biology of DNA quadruplexes continues to develop.…”

Section: The Chemical Biology Of Nucleic Acidsmentioning

confidence: 99%