Perfluoroalkanesulfonyl fluorides are effective dehydroxy-fluorination agents for the hydroxyl group at the sugar moiety of nucleoside derivatives and give the corresponding fluorinated nucleosides in good yield with an inversion of configuration in a single step.

Nucleic acids Nucleic acids U 0700Convenient Synthesis of Fluorinated Nucleosides with Perfluoroalkanesulfonyl Fluorides. -Perfluoroalkanesulfonyl fluorides can be used for dehydroxy-fluorination in a single step with inversion of configuration. A combination of perfluoro-1-butanesulfonyl fluoride with N-ethylpiperidine or N,N-dimethylcyclohexylamine as a base provides satisfactory results regarding selectivity between fluorination and elimination. Thus, the 2'-hydroxyl group of (I) is converted into the 2'-β fluoride (II), which is further transformed into the anti-HIV nucleoside FddA (IV), after decomposition of elimination product (III). The applicability of this system for dehydroxy-fluorination is further demonstrated with other nucleosides. This method avoids corrosive reagents or column separation. -(TAKAMATSU*, S.; KATAYAMA, S.; HIROSE, N.; DE COCK, E.; SCHELKENS, G.; DEMILLEQUAND, M.; BREPOELS, J.; IZAWA, K.; Nucleosides, Nucleotides Nucleic Acids 21 (2002) 11-12, 849-861; AminoSci. Lab., Ajinomoto Co., Inc., Kawasaki 210, Japan; Eng.) -H. Hoennerscheid 16-214 2003 Nucleic acids

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The peptide bond between Pro‐Leu or Leu‐Gly in Pro‐Leu‐Gly‐NH2 was replaced by a CH2‐NH function. The 1H and 13C n.m.r. studies demonstrated that HCl·Pro‐Leu (CH2‐NH)Gly‐NH2 10 adopted a conformation in DMSO that is similar to the previously postulated β‐turn for the natural hormone. This was not the case for the other analogue. In vivo tests on 10 revealed an activity approximately equal to the natural compound and an increased toxicity.

The synthesis of bradykinin analogues is described in which the Gly'-Phes, Phes-Ser6 or the Pro7-Phea peptide bond has been replaced by a trans carbon-carbon double bond or by a "reduced" peptide bond. Some of the analogues display high potency and prolonged activity in the rat blood pressure test, indicating increased metabolic stability. A clear selectivity is obtained towards the myotropic effect in the guinea pig i leum.Bradykinin (BK) Arg' -Pro2 -Pro3 -Gly' -Phes -Ser6 -Pro7 -Phe* -Argg A r g -P r o -P r o -G l y -P h e -S e r -P r o $