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Hiroshi Suemune

Publications and source records attributed to Hiroshi Suemune.

17 recordsLinked to original sources
PubMed2006

Photochemical generation of C4'-oxidized abasic site containing oligodeoxynucleotide and its efficient amine modification.

[Structure: see text] We synthesized oligodeoxynucleotide (ODN, 3), which contains 4'-o-nitrobenzyloxythymidine (4) as a caged precursor of C4'-oxidized abasic site (1). Photoirradiation of 3 at 365 nm followed by amine treatment under neutral conditions afforded the lactam (2) efficiently. Duplexed ODN 3 was converted to 1 faster and more efficiently than single stranded 3, whereas amine treatment of 1 formed from single stranded 3 resulted in slightly faster lactam formation than with the duplex.

Amines↗
PubMed2006

Photochemical generation of C4'-oxidized abasic site containing oligonucleotide and its amine modification reaction.

We studied photochemical generation of oligodeoxynucleotide (ODN) containing C4'-oxidized abasic site (1) from its caged precursor 3. Photoirradiation of 3 at 365 nm followed by amine treatment under neutral conditions afforded the lactam (2) efficiently. Duplexed ODN 3 was converted to 1 faster and more efficiently than single stranded 3, whereas amine treatment of 1 formed from single stranded 3 resulted in slightly faster lactam formation than with duplex.

Amines↗
PubMed2005

Synthesis and EPR studies of 2-N-tert-butylaminoxylpurine derivatives.

[Structure: see text] 2'-Deoxyribofuranosylpurine derivatives bearing an N-tert-butylaminoxyl group (1a and 2a) were synthesized via oxidation of the corresponding N-tert-butylhydroxylamines (1b and 2b), which were synthesized by lithiation of 8-TIPS-6-chloropurine (3) at the 2-position and the following reaction with 2-methyl-2-nitrosopropane. Treatment of 1b and 2b with 1 equiv of NaIO4 resulted in efficient formation of 1a and 2a, which were isolated as purple and red solids, respectively. The EPR spectra of 1a showed pH dependency due to structural change of purine moiety.

Amines↗
PubMed2005

Amine modification reaction of C4'-oxidized abasic site generated from its caged precursors.

A method for the generation of ODNs containing a C4'-oxidized abasic site (C4'-OAS) from "photocaged" ODNs was investigated. We synthesized C4'-caged ODN 1 and C1'-caged ODN 2 bearing an o-nitrobenzyloxy group at the C-4' position and the C-1' position, respectively. The duplex stabilities of 1 and 2, with their complementary ODNs were studied by Tm measurements. The photochemical reaction of 1 and 2 to generate ODN 3 containing C4'-OAS, and the subsequent amine modification reaction were studied.

Amines↗
PubMed2005

Properties and EPR studies of oligodeoxynucleotides containing 2-N-tert-butylaminoxylpurines.

Oligodeoxynucleotide (ODN; 1) containing 2-N-tert-butylaminoxyladenosine (2) was synthesized by the conventional phosphoramidite method. The thermal stability and structure of the duplex of ODN 1 and the complementary strand were elucidated by UV-melting temperature measurements and CD experiments. In phosphate buffer, ODN 1 showed a three line EPR spectrum. Upon duplex formation, the EPR spectrum of 1 changed which indicates that EPR spectra of 1 can provide information on structures of ODN.

Adenosine↗
PubMed2004

Double-chelation-assisted Rh-catalyzed intermolecular hydroacylation between salicylaldehydes and 1,4-penta- or 1,5-hexadienes.

Intermolecular hydroacylation between salicylaldehydes 1, 26-40 and 1,4-penta- or 1,5-hexadienes 4-13 by Rh-catalyst proceeded under mild reaction conditions to give a mixture of iso- and normal-hydroacylated products 14-25, 41-55, and 57-60. In the hydroacylation reaction, chelation of both salicylaldehyde and diene to the Rh-complex plays a crucial role. The ratio of iso- and normal-hydroacylated products could be regulated by the addition of salicylic acid or amines. The effects of various Rh-complexes, solvents, and additives were examined, and the plausible mechanisms of the catalytic cycle were proposed on the basis of the deuterium-labeling salicylaldehyde experiments.

Journal Article↗
PubMed2004

Synthesis of oligonucleotide containing 4'-o-nitrobenzyloxythymidine and its reactivity.

We synthesized oligonucleotide (1) containing 4'-o-nitrobenzyloxythymidine (2), which was prepared by reaction of 4',5'-unsaturated thymidine with m-CPBA followed by Lewis-acid catalyzed addition of o-nitrobenzylalcohol. The duplex stability of 1 with the complementary oligonucleotide was studied by Tm measurement. Photochemical reaction of 1 to generate C4'-oxidized abasic site containing oligonucleotide (3) was studied.

Chromatography, High Pressure Liquid↗
PubMed2003

An extended planar C5 conformation and a 310-helical structure of peptide foldamer composed of diverse alpha-ethylated alpha,alpha-disubstituted alpha-amino acids.

Optically active peptide foldamers Tfa-[(S)-(alphaEt)Leu]-[(S)-(alphaEt)Nva]-Deg-[(S)-(alphaEt)Nle]-OEt (10) and Tfa-[(S)-(alphaEt)Val]-[(S)-(alphaEt)Leu]-[(S)-(alphaEt)Nva]-Deg-[(S)-(alphaEt)Nle]-OEt (11) composed of diverse alpha-ethylated alpha,alpha-disubstituted alpha-amino acids were synthesized. The dominant conformation of these peptides in solution was an unusual, fully extended planar conformation, and that in the crystal state was both right-handed (P) and left-handed (M) 3(10)-helical structures in 10 and a P 3(10)-helical structure in 11, respectively. The preferred planar C(5) conformation of the peptides prepared from chiral alpha-ethylated alpha,alpha-disubstituted alpha-amino acids was drastically different from the 3(10)-helical structure of the peptides prepared from chiral alpha-methylated alpha,alpha-disubstituted alpha-amino acids.

Amino Acids↗
PubMed2003

A simple and efficient method for synthesis of 5-substituted 2'-deoxyuridine nucleosides using metal-halogen exchange reaction of 5-iodo-2'-deoxyuridine sodium salt.

Treatment of the sodium salt of 2'-deoxy-3', 5'-bis-O-(tert-butyldimethylsilyl)-5-iodouridine (3) with n-BuLi effected regioselective lithiation at the 5-position and the following reaction with various electrophiles afforded 5-substituted 2'-deoxyuridines including 1b, the precursor of stable spin-labeled 1a, in good yields.

Idoxuridine↗
PubMed2003

Double-chelation-assisted Rh-catalyzed intermolecular hydroacylation.

[reaction: see text] Rh-Catalyzed intermolecular hydroacylation between salicylaldehydes and 1,5-hexadienes proceeded under remarkably mild reaction conditions to afford a mixture of iso- and normal-hydroacylated products in good yields. The experiments using deuterated salicylaldehyde-d revealed that "double chelation" of salicylaldehyde and 1,5-hexadiene to Rh-complex played vital roles in the catalytic cycle of intermolecular hydroacylation.

Journal Article↗
PubMed2003

Synthetic studies and properties of N-tert-butylaminoxyl nucleosides.

We synthesized 5-N-tert-butylhydroxylamino-2'-deoxyuridine (9b) via lithium-halogen exchange reaction of sodium salt of 5-iodo-2'-deoxyuridine (8b). This procedure was applicable to synthesis of the corresponding uridine (9a) and N-benzoyl cytidine (13). Obtained 9b was converted into stable aminoxyl (5a) by treatment with Ag2O to study its properties as a novel spin-labeled nucleoside.

Electron Spin Resonance Spectroscopy↗
PubMed2002

Synthesis and properties of N-t-butylaminoxyl nucleosides.

Novel purine nucleosides with a N-tert-butylhydroxylamino group at the 2-position of purine nucleus (1-3) were synthesized, which might prefer anti conformation and would not perturb DNA structure when incorporated into oligonucleotide. Oxidation of 1-3 by treatment with Ag2O or air afforded stable aminoxyl radicals (1'-3') and their properties were studied by EPR spectroscopy. 5-N-tert-butylhydroxylamino uridine (4) was also synthesized.

Electron Spin Resonance Spectroscopy↗
PubMed1996

Chemoenzymatic Synthesis of Antiviral Carbocyclic Nucleosides: Asymmetric Hydrolysis of meso-3,5-Bis(acetoxymethyl)cyclopentenes Using Rhizopusdelemar Lipase.

7-Substituted norbornadienes were stereoselectively converted into the meso-3,5-bis(acetoxymethyl)cyclopentenes by a three-step sequence of ozonolysis, reduction, and acetylation. Rhizopus delemar lipase (RDL)-catalyzed asymmetric hydrolysis of meso-3,5-bis(acetoxymethyl)cyclopentenes afforded the monoalcohols of high enantiomeric purities (>95% ee) in good yields (64-95%). The obtained monoalcohols 11 and 14 could be applied for the synthesis of antiviral carbocyclic nucleosides (-)-carbovir and (-)-BCA.

Journal Article↗