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Eleuteri A, Cheruvallath ZS, Capaldi DC, Krotz AH, Cole DL, Ravikumar VT. Oligodeoxyribonucleotide Phosphorothioates: Substantial Reduction of (N-1)-Mer Content Through the Use of Blockmer Phosphoramidite Synthons. ACTA ACUST UNITED AC 2006. [DOI: 10.1080/07328319908044665] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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2
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Krotz AH, Cole DL, Ravikumar VT. Dimethoxytrityl Removal in Organic Medium: Efficient Oligonucleotide Synthesis Without Chlorinated Solvents. ACTA ACUST UNITED AC 2006. [DOI: 10.1080/07328319908044664] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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3
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Rentel C, Wang X, Batt M, Kurata C, Oliver J, Gaus H, Krotz AH, McArdle JV, Capaldi DC. Formation of modified cytosine residues in the presence of depurinated DNA. J Org Chem 2006; 70:7841-5. [PMID: 16277303 DOI: 10.1021/jo050767f] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
[Chemical reaction: See text] Depurination is an important degradation pathway for antisense phosphorothioate oligonucleotides under conditions of thermal stress. We present evidence showing that depurinated oligonucleotides react with cytosine-containing sequences giving products containing a 6-(2-deoxy-beta-D-erythro-pentofuranosyl)-3-(2-oxopropyl)imidazo[1,2-c]pyrimidin-5(6H)-one residue. Further, we demonstrate that the same product is formed upon treatment of 2'-deoxycytidine with 4-oxo-2-pentenal, the latter being an expected byproduct of serial elimination reactions at apurinic sites. In addition to being important for synthetic oligonucleotides, apurinic site formation in cellular DNA is a common occurrence. Because repair of these sites can result in the production of 4-oxo-2-pentenal, it is interesting to speculate whether 6-(2-deoxy-beta-D-erythro-pentofuranosyl)-3-(2-oxopropyl)imidazo[1,2-c]pyrimidin-5(6H)-one residues can form in vivo.
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Affiliation(s)
- Claus Rentel
- Isis Pharmaceuticals, Inc., 1896 Rutherford Road, Carlsbad, California 92008, USA
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Krotz AH, Hang A, Gorman D, Scozzari AN. Polysulfide reagent in solid-phase synthesis of phosphorothioate oligonucleotides: greater than 99.8% sulfurization efficiency. Nucleosides Nucleotides Nucleic Acids 2005; 24:1293-9. [PMID: 16252666 DOI: 10.1080/15257770500230384] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
A solution of sulfur (0.1 M) and sodium sulfide (0.01M) in 3-picoline, referred to as polysulfide reagent, rapidly converts trialkyl and triaryl phosphite triesters to the corresponding phosphorothioate derivatives. Greater than 99.8% average stepwise sulfurization efficiency is obtained in the solid-phase synthesis of DNA and RNA phosphorothioate olgonucleotides via the phosphoramidite approach.
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Affiliation(s)
- Achim H Krotz
- Isis Pharmaceuticals, Inc., Carlsbad, California 92008, USA
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Krotz AH, Gaus H, Hardee GE. Formation of oligonucleotide adducts in pharmaceutical formulations. Pharm Dev Technol 2005; 10:283-90. [PMID: 15926677 DOI: 10.1081/pdt-54464] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
During preformulation studies, we observed that oligonucleotide extracted from topical formulations contained considerable amounts of covalently modified oligonucleotide adducts. In this report, we describe the identification and characterization of reaction products that form when PS-oligodeoxyribonucleotide ISIS 2302 (1) is brought into contact with aqueous solutions of glycerol-derived excipients. Compatibility tests showed that the presence of certain glycerides in the formulation lead to adduct formation (1+58x amu, 1+72x amu, 1+58x+72y amu, x, and y are the number of modifications on one oligonucleotide strand). No adduct formation was observed in the presence of triglycerides or propylene glycol-derived excipients used in the study. Using nucleosides as model compounds, two modifications of deoxyguanosine were isolated by preparative reversed phase (RP)-high pressure liquid chromatography (HPLC) and characterized by nuclear magnetic resonance (NMR) and HPLC-mass spectrometry (MS). Modifications were identified as N2-(1-carboxymethyl)- and N2-(1-carboxyethyl) derivatives of 2'-deoxyguanosine. The mechanism of formation of these adducts may involve advanced glycation reactions possibly caused by excipient impurities or degradation products such as glyceraldehyde or glyceraldehyde derivatives.
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Affiliation(s)
- Achim H Krotz
- Isis Pharmaceuticals, Inc., 2292 Faraday Avenue, Carlsbad, CA 92008, USA.
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Abstract
Desulfurization at the internucleotide phosphorothioate linkage of antisense oligonucleotides (ASOs) in dermatological formulations has been investigated using strong ion exchange chromatography and mass spectroscopy. The formation of phosphate diester linkages appeared to arise from a reaction between the phosphorothioate oligonucleotide and a potent oxidizing agent. Screening of excipients used in the formulation indicated that the cause of desulfurization was related to the presence of polyethylene glycol-derived nonionic surfactants MYRJ 52 or BRIJ 58. Autoxidation of the polyethylene glycol chain is suggested as the probable origin for the observed incompatibility. The ability of various antioxidants to prevent oxidative degradation of ASO-1 in simple test systems and in oil-in-water emulsions is described. It is found that in test systems both lipophilic and hydrophilic antioxidants are effective. However, in cream formulation (oil-in-water emulsions) of ASO-1 the addition of hydrophilic antioxidants L-cysteine or DL-alpha-lipoic acid has been shown to be superior in protecting the oligonucleotide from desulfurization upon storage.
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Affiliation(s)
- Achim H Krotz
- Isis Pharmaceuticals, Inc., 2292 Faraday Ave., Carlsbad, California 92008, USA.
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Capaldi DC, Gaus HJ, Carty RL, Moore MN, Turney BJ, Decottignies SD, McArdle JV, Scozzari AN, Ravikumar VT, Krotz AH. Formation of 4,4'-dimethoxytrityl-C-phosphonate oligonucleotides. Bioorg Med Chem Lett 2005; 14:4683-90. [PMID: 15324888 DOI: 10.1016/j.bmcl.2004.06.088] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2004] [Accepted: 06/28/2004] [Indexed: 11/18/2022]
Abstract
Incomplete sulfurization during solid-phase synthesis of phosphorothioate oligonucleotides using phosphoramidite chemistry was identified as the cause of formation of two new classes of process-related oligonucleotide impurities containing a DMTr-C-phosphonate (DMTr=4,4'-dimethoxytrityl) moiety. Phosphite triester intermediates that failed to oxidize (sulfurize) to the corresponding phosphorothioate triester react during the subsequent acid-induced (dichloroacetic acid) detritylation with the DMTr cation or its equivalent in an Arbuzov-type reaction. This leads to formation of DMTr-C-phosphonate mono- and diesters resulting in oligonucleotides modified with a DMTr-C-phosphonate moiety located internally or at the 5'terminal hydroxy group. DMTr-C-phosphonate derivatives are not detected when optimized sulfurization conditions are employed.
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Affiliation(s)
- Daniel C Capaldi
- Isis Pharmaceuticals, Inc., 2292 Faraday Avenue, Carlsbad, CA 92008, USA
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Krotz AH, Rentel C, Gorman D, Olsen P, Gaus HJ, McArdle JV, Scozzari AN. Solution stability and degradation pathway of deoxyribonucleoside phosphoramidites in acetonitrile. Nucleosides Nucleotides Nucleic Acids 2005; 23:767-75. [PMID: 15281365 DOI: 10.1081/ncn-120039215] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The impuritiy profiles of acetonitrile solutions of the four standard O-cyanoethyl-N,N-diisopropyl-phosphoramidites of 5'-O-dimethoxytrityl (DMT) protected deoxyribonucleosides (dG(ib), dA(bz), dC(bz), T) were analyzed by HPLC-MS. The solution stability of the phosphoramidites decreases in the order T, dC>dA>dG. After five weeks storage under inert gas atmosphere the amidite purity was reduced by 2% (T, dC), 6% (dA), and 39% (dG), respectively. The main degradation pathways involve hydrolysis, elimination of acrylonitrile and autocatalytic acrylonitrile-induced formation of cyanoethyl phosphonoamidates. Consequently, the rate of degradation is reduced by reducing the water concentration in solution with molecular sieves and by lowering the amidite concentration. Acid-catalyzed hydrolysis could also be reduced by addition of small amounts of base.
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Affiliation(s)
- Achim H Krotz
- Drug Substance Manufacturing, Isis Pharmaceuticals, Inc., Carlsbad, California 92008, USA.
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Krotz AH, Gorman D, Mataruse P, Foster C, Godbout JD, Coffin CC, Scozzari AN. Phosphorothioate Oligonucleotides with Low Phosphate Diester Content: Greater than 99.9% Sulfurization Efficiency with “Aged” Solutions of Phenylacetyl Disulfide (PADS). Org Process Res Dev 2004. [DOI: 10.1021/op040208v] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Achim H. Krotz
- Isis Pharmaceuticals, Inc., 2292 Faraday Avenue, Carlsbad, California 92008
| | - Dennis Gorman
- Isis Pharmaceuticals, Inc., 2292 Faraday Avenue, Carlsbad, California 92008
| | - Paul Mataruse
- Isis Pharmaceuticals, Inc., 2292 Faraday Avenue, Carlsbad, California 92008
| | - Craig Foster
- Isis Pharmaceuticals, Inc., 2292 Faraday Avenue, Carlsbad, California 92008
| | - James D. Godbout
- Isis Pharmaceuticals, Inc., 2292 Faraday Avenue, Carlsbad, California 92008
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Affiliation(s)
- Max N. Moore
- Isis Pharmaceuticals, Inc., 2292 Faraday Avenue, Carlsbad, California 92008, U.S.A
| | - Mark Andrade
- Isis Pharmaceuticals, Inc., 2292 Faraday Avenue, Carlsbad, California 92008, U.S.A
| | - Anthony N. Scozzari
- Isis Pharmaceuticals, Inc., 2292 Faraday Avenue, Carlsbad, California 92008, U.S.A
| | - Achim H. Krotz
- Isis Pharmaceuticals, Inc., 2292 Faraday Avenue, Carlsbad, California 92008, U.S.A
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Capaldi DC, Gaus H, Krotz AH, Arnold J, Carty RL, Moore MN, Scozzari AN, Lowery K, Cole DL, Ravikumar VT. Synthesis of High-Quality Antisense Drugs. Addition of Acrylonitrile to Phosphorothioate Oligonucleotides: Adduct Characterization and Avoidance. Org Process Res Dev 2003. [DOI: 10.1021/op020090n] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Daniel C. Capaldi
- Isis Pharmaceuticals, Inc., 2292 Faraday Avenue,Carlsbad, California 92008, U.S.A
| | - Hans Gaus
- Isis Pharmaceuticals, Inc., 2292 Faraday Avenue,Carlsbad, California 92008, U.S.A
| | - Achim H. Krotz
- Isis Pharmaceuticals, Inc., 2292 Faraday Avenue,Carlsbad, California 92008, U.S.A
| | - Jim Arnold
- Isis Pharmaceuticals, Inc., 2292 Faraday Avenue,Carlsbad, California 92008, U.S.A
| | - Ricaldo L. Carty
- Isis Pharmaceuticals, Inc., 2292 Faraday Avenue,Carlsbad, California 92008, U.S.A
| | - Max N. Moore
- Isis Pharmaceuticals, Inc., 2292 Faraday Avenue,Carlsbad, California 92008, U.S.A
| | - Anthony N. Scozzari
- Isis Pharmaceuticals, Inc., 2292 Faraday Avenue,Carlsbad, California 92008, U.S.A
| | - Kirsten Lowery
- Isis Pharmaceuticals, Inc., 2292 Faraday Avenue,Carlsbad, California 92008, U.S.A
| | - Douglas L. Cole
- Isis Pharmaceuticals, Inc., 2292 Faraday Avenue,Carlsbad, California 92008, U.S.A
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Abstract
The removal of 4,4'-dimethoxytrityl (DMTr) groups from oligonucleotides at low pH and the acid lability of the glycosidic linkage of purine nucleotides constitute an inherent conflict in preparative oligonucleotide chemistry. The use of a mildly acidic NaOAc buffer (10 mM, pH 3.0-3.2) allows adjustment of the pH in a range where the progress of the DMTr removal reaction can be monitored conveniently by HPLC and the optimum reaction time can be calculated. As a result, oligonucleotides with minimum depurination are obtained.
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Affiliation(s)
- Achim H Krotz
- Isis Pharmaceuticals, Inc., Carlsbad, California 92008, USA.
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Affiliation(s)
- Achim H. Krotz
- Isis Pharmaceuticals, Inc., 2292 Faraday Avenue, Carlsbad, California 92008, U.S.A
| | - Bethany McElroy
- Isis Pharmaceuticals, Inc., 2292 Faraday Avenue, Carlsbad, California 92008, U.S.A
| | - Anthony N. Scozzari
- Isis Pharmaceuticals, Inc., 2292 Faraday Avenue, Carlsbad, California 92008, U.S.A
| | - Douglas L. Cole
- Isis Pharmaceuticals, Inc., 2292 Faraday Avenue, Carlsbad, California 92008, U.S.A
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Krotz AH, Kuo LY, Barton JK. Metallointercalators: syntheses, structures, and photochemical characterizations of phenanthrenequinone diimine complexes of rhodium(III). Inorg Chem 2002. [DOI: 10.1021/ic00078a012] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Krotz AH, Barton JK. Rational Construction of Metallointercalators: Syntheses, Structures, and Characterizations of Isomers of ((2S,9S)-Diamino-4,7-diazadecane)(9,10-phenanthrenequinone diimine)rhodium(III). Inorg Chem 2002. [DOI: 10.1021/ic00087a034] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Krotz AH, Hudson BP, Barton JK. Assembly of DNA recognition elements on an octahedral rhodium intercalator: predictive recognition of 5'-TGCA-3' by .DELTA.-[Rh(R,R)-Me2trien]phi]3+. J Am Chem Soc 2002. [DOI: 10.1021/ja00079a044] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Krotz AH, Kuo LY, Shields TP, Barton JK. DNA recognition by rhodium(III) polyamine intercalators: considerations of hydrogen bonding and van der Waals interactions. J Am Chem Soc 2002. [DOI: 10.1021/ja00063a004] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Abstract
High-quality oligonucleotides are obtained by selective modification of sequences containing aldehyde apurinic sites with a new chromatographic tag followed by RP-HPLC separation. Hydroxylamine derivative 1 of a water soluble nonionic surfactant modifies oligonucleotides selectively at abasic sites leading to significantly increased retention.
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Affiliation(s)
- A H Krotz
- Isis Pharmaceuticals Inc., 2292 Faraday Avenue, 92008, Carlsbad, CA, USA.
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Eleuteri A, Capaldi DC, Krotz AH, Cole DL, Ravikumar VT. Pyridinium Trifluoroacetate/N-Methylimidazole as an Efficient Activator for Oligonucleotide Synthesis via the Phosphoramidite Method. Org Process Res Dev 2000. [DOI: 10.1021/op9900378] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
| | - Daniel C. Capaldi
- Isis Pharmaceuticals, 2292 Faraday Avenue, Carlsbad, California 92008
| | - Achim H. Krotz
- Isis Pharmaceuticals, 2292 Faraday Avenue, Carlsbad, California 92008
| | - Douglas L. Cole
- Isis Pharmaceuticals, 2292 Faraday Avenue, Carlsbad, California 92008
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Krotz AH, Carty RL, Scozzari AN, Cole DL, Ravikumar VT. Large-Scale Synthesis of Antisense Oligonucleotides without Chlorinated Solvents. Org Process Res Dev 1999. [DOI: 10.1021/op990183d] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Achim H. Krotz
- Isis Pharmaceuticals, Inc., 2292 Faraday Avenue, Carlsbad, California 92008, U.S.A
| | - Recaldo L. Carty
- Isis Pharmaceuticals, Inc., 2292 Faraday Avenue, Carlsbad, California 92008, U.S.A
| | - Anthony N. Scozzari
- Isis Pharmaceuticals, Inc., 2292 Faraday Avenue, Carlsbad, California 92008, U.S.A
| | - Douglas L. Cole
- Isis Pharmaceuticals, Inc., 2292 Faraday Avenue, Carlsbad, California 92008, U.S.A
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Cheruvallath ZS, Carty RL, Moore MN, Capaldi DC, Krotz AH, Wheeler PD, Turney BJ, Craig SR, Gaus HJ, Scozzari AN, Cole DL, Ravikumar VT. Synthesis of Antisense Oligonucleotides: Replacement of 3H-1,2-Benzodithiol-3-one 1,1-Dioxide (Beaucage Reagent) with Phenylacetyl Disulfide (PADS) As Efficient Sulfurization Reagent: From Bench to Bulk Manufacture of Active Pharmaceutical Ingredient. Org Process Res Dev 1999. [DOI: 10.1021/op990077b] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | - Recaldo L. Carty
- Isis Pharmaceuticals, 2290 Faraday Avenue, Carlsbad California 92008, U.S.A
| | - Max N. Moore
- Isis Pharmaceuticals, 2290 Faraday Avenue, Carlsbad California 92008, U.S.A
| | - Daniel C. Capaldi
- Isis Pharmaceuticals, 2290 Faraday Avenue, Carlsbad California 92008, U.S.A
| | - Achim H. Krotz
- Isis Pharmaceuticals, 2290 Faraday Avenue, Carlsbad California 92008, U.S.A
| | - Patrick D. Wheeler
- Isis Pharmaceuticals, 2290 Faraday Avenue, Carlsbad California 92008, U.S.A
| | - Brett J. Turney
- Isis Pharmaceuticals, 2290 Faraday Avenue, Carlsbad California 92008, U.S.A
| | - Stephen R. Craig
- Isis Pharmaceuticals, 2290 Faraday Avenue, Carlsbad California 92008, U.S.A
| | - Hans J. Gaus
- Isis Pharmaceuticals, 2290 Faraday Avenue, Carlsbad California 92008, U.S.A
| | | | - Douglas L. Cole
- Isis Pharmaceuticals, 2290 Faraday Avenue, Carlsbad California 92008, U.S.A
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Krotz AH, Cole DL, Ravikumar VT. Synthesis of an antisense oligonucleotide targeted against C-raf kinase: efficient oligonucleotide synthesis without chlorinated solvents. Bioorg Med Chem 1999; 7:435-9. [PMID: 10220029 DOI: 10.1016/s0968-0896(98)00253-3] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
It is demonstrated that a solution of dichloroacetic acid in toluene removes dimethoxytrityl groups from the 5'-terminus of an antisense phosphorothioate oligodeoxyribonucleotide (ISIS 5132/CGP69846A) during synthesis on solid support cleanly and efficiently. It is therefore suggested to replace health hazardous dichloromethane which is typically used in oligonucleotide synthesis as solvent for DMTr-removal by toluene.
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Affiliation(s)
- A H Krotz
- Isis Pharmaceuticals Inc., Carlsbad, CA 92008, USA
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Abstract
'Retro-inverso' peptide nucleic acid (PNA) monomers of thymine (T*: N-(amidomethyl)-N-(N1-thyminyl-acetyl)-beta-alanyl) (and adenine) have been prepared and introduced in PNA oligomers. A homo 'retro-inverso' T*8 PNA was found not to hybridize to a complementary DNA or RNA oligonucleotide, whereas introduction of one retro-inverso thymine unit into the middle of a normal PNA 15-mer resulted in a c.a. 8 degrees C destabilization of the complex of this oligomer with a complementary DNA or RNA oligomer. In an effort to compensate for the structural nucleobase 'phase-shift' caused by the T* monomer by also introducing a beta-alanine monomer it is concluded that the effect of the T* backbone is -7 degrees C when hybridizing to DNA and -4.5 degrees C when hybridizing to RNA. Nonetheless, the T* unit shows good sequence discrimination comparable to that of normal PNA. Molecular dynamics simulations indicate an unfavourable conformation of the backbone amide carbonyl group resulting in reduced interaction with the aqueous medium and an 'electrostatic clash' with the carbonyl of the nucleobase linker. These results show that a simple inversion of an amide bond in the PNA backbone has a dramatic, and hardly predictable, effect on the DNA mimicking properties of the oligomer.
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Affiliation(s)
- A H Krotz
- Center for Biomolecular Recognition, H. C. Orsted Institute, University of Copenhagen, Denmark
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Krotz AH, Klopchin P, Cole DL, Ravikumar VT. Improved Impurity Profile of Phosphorothioate Oligonucleotides Through the Use of Dimeric Phosphoramidite Synthons. ACTA ACUST UNITED AC 1997. [DOI: 10.1080/07328319708006244] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Krotz AH, Klopchin PG, Walker KL, Srivatsa G, Cole DL, Ravikumar VT. On the formation of longmers in phosphorothioate oligodeoxyribonucleotide synthesis. Tetrahedron Lett 1997. [DOI: 10.1016/s0040-4039(97)00798-3] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Krotz AH, Klopchin P, Cole DL, Ravikumar VT. Phosphorothioate oligonucleotides: Largely reduced (N-1)-mer and phosphodiester content through the use of dimeric phosphoramidite synthons. Bioorg Med Chem Lett 1997. [DOI: 10.1016/s0960-894x(96)00573-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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27
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Krotz AH, Buchardt O, Nielsen PE. Synthesis of ‘retro-inverso’ peptide nucleic acids: 2. Oligomerization and stability. Tetrahedron Lett 1995. [DOI: 10.1016/0040-4039(95)01375-r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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31
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Krotz AH, Buchardt O, Nielsen PE. Synthesis of ‘retro-inverso’ peptide nucleic acids: 1. Characterization of the monomers. Tetrahedron Lett 1995. [DOI: 10.1016/0040-4039(95)01374-q] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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32
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Ravikumar VT, Krotz AH, Cole DL. Efficient synthesis of deoxyribonucleotide phosphorothioates by the use of DMT cation scavenger1. Tetrahedron Lett 1995. [DOI: 10.1016/00404-0399(50)1346-j] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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