2885-02-1Relevant articles and documents
Novel tenofovir mixed ester-amide prodrugs
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Paragraph 0058-0060, (2020/04/17)
The invention relates to novel tenofovir mixed ester-amide prodrugs or pharmaceutically acceptable salts thereof, a preparation method thereof, pharmaceutical compositions containing the prodrug compounds, and application of the prodrugs in preparation of drugs for treating virus infection such as hepatitis B virus (HBV) or human immunodeficiency virus (HIV) infection.
A mild removal of Fmoc group using sodium azide
Chen, Chun-Chi,Rajagopal, Basker,Liu, Xuan Yu,Chen, Kuan Lin,Tyan, Yu-Chang,Lin, Fui,Lin, Po-Chiao
, p. 367 - 374 (2014/03/21)
A mild method for effectively removing the fluorenylmethoxycarbonyl (Fmoc) group using sodium azide was developed. Without base, sodium azide completely deprotected Nα-Fmoc-amino acids in hours. The solvent-dependent conditions were carefully studied and then optimized by screening different sodium azide amounts and reaction temperatures. A variety of Fmoc-protected amino acids containing residues masked with different protecting groups were efficiently and selectively deprotected by the optimized reaction. Finally, a biologically significant hexapeptide, angiotensin IV, was successfully synthesized by solid phase peptide synthesis using the developed sodium azide method for all Fmoc removals. The base-free condition provides a complement method for Fmoc deprotection in peptide chemistry and modern organic synthesis. Graphical Abstract: [Figure not available: see fulltext.]
Preparation of 2,3,4-trisubstituted piperidines by a formal hetero-ene reaction of amino acid derivatives
Laschat, Sabine,Froehlich, Roland,Wibbeling, Birgit
, p. 2829 - 2838 (2007/10/03)
N-Benzyl- or N-tosyl-N-(4-methyl-3-pentenyl)amino aldehyde benzylimines, which are obtained from alanine, leucine, or phenylalanine methyl esters in five steps, can be cyclized diastereoselectively in the presence of Lewis acids to give 3-amino-2,4-dialkyl-substituted piperidines. The product distribution and diastereoselectivity depends on the type of Lewis acid and nitrogen-protecting group. Benzyl-protected imines give 2-alkyl-3-(benzylamino)-4-isopropenyl piperidines with FeCl3 and 2-alkyl-3-(benzylideneamino)-4-isopropylpiperidines with TiCl4. Tosyl-protected imines show a decreased level of selectivity. The relative configurations of the piperidines were established by NMR and X-ray crystal structure analyses. Iminium ion cyclization followed by two competitive ionic pathways, i.e. either proton elimination or hydride transfer are discussed for these reactions.