10.1039/b403652b
The study focuses on the synthesis and evaluation of two new zinc ion-dependent oligonucleotide-based artificial nucleases (OBANs), OBAN 4 and OBAN 5. These OBANs are composed of 2'-O-methyl modified RNA oligomers conjugated to 5-amino-2,9-dimethylphenanthroline (neocuproine) via a urea linker. OBAN 4 features the catalytic group on a linker extending from the C-4 of an internal cytosine, while OBAN 5 has two neocuproine units attached via linkers from the C-5 position of uridine moieties. The synthesis involves conjugating the catalytic group to the amino linkers of the modified oligonucleotides by converting 5-amino-2,9-dimethylphenanthroline to phenylcarbamate and reacting it with oligonucleotides carrying primary aliphatic amines in aqueous buffer. Both OBAN systems are found to cleave RNA in bulged-out regions from non-complementary parts of the target sequences in the presence of Zn(II) ions, with differences in efficiency compared to previous systems discussed. The study also explores the influence of linker and linker position, as well as target RNA structure, on cleavage efficiency, providing insights into the development of more efficient OBAN systems for potential applications in life science and biotechnology.
10.1002/chem.200400733
The research focuses on the practical synthesis of (+)-biotin from l-cysteine, a significant endeavor due to biotin's crucial role in human nutrition and animal health. The study aims to address the inefficiencies of the existing Goldberg and Sternbach method, which involves over 14 steps, utilizes toxic reagents, and requires impractical diastereomeric or enzymatic resolution. The researchers developed a novel synthetic approach that eliminates the need for bulky protecting groups and reduces the protection-deprotection sequence steps. This method involves the formation of contiguous stereogenic centers through a highly diastereoselective Strecker reaction, a novel ring transformation and deblocking by S,N-carbonyl migration, and the introduction of the carbon chain at C-4 by the Fukuyama coupling reaction. Key chemicals used in the process include l-cysteine, phenyl chloroformate, benzyl bromide, benzyl chloride, sodium bisulfite, sodium cyanide, and various catalysts and reagents for the reactions involved. The conclusions of the research highlight the successful development of a more efficient synthetic method for (+)-biotin, achieved in 10 steps and with an overall yield of 34% from l-cysteine, offering a high yield, ease of operation, and mild reaction conditions.
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