B. Castro

Synthesis of homogeneous polyoxyethylene perfluorcalkyl surfactants: A new method

Abstract Polyoxyethylene perfluoroalkyl surfactants are synthesized from polyoxyethylene glycols using an appropriate intermediate monooxyphosphonium salt. In contrast with methods involving the polyaddition of ethylene oxide to a fluoroalcohol, the present procedure allows us to obtain surfactant molecules with a definite number of oxyethylene units, i.e. with a well-defined hydrophile lipophile balance (HLB). Fluorinated microemulsions could thus be prepared for the first time by mixing the surfactant of appropriate HLB to water and a fluorocarbon.

Synthesis of LH-RH using a new phenolic polymer as solid support and “BOP” reagent for fragment coupling

Abstract p-Hydroxyphenyl propionic resin (Table I, compound 4) was used to prepare the 1–6 protected fragment of LH-RH which was then condensed with “BOP” (benzotriazolyl N-oxytrisdimethylaminophosphonium hexafluorophosphate) as coupling reagent to the 7–10 residue synthesized on the same resin. Peptidylresin was divided into two aliquots in order to obtain LH-RH after aminolysis and treatment with liquid hydrogen fluoride, LH-RH-COOH after saponification followed by hydrogenation, or treatment with liquid hydrogen fluoride. The resulting hormones were rapidly purified by the sole means of two gel filtrations.

Synthetic porphyrins bearing a lateral peptide chain—V : On the lack of evidence from exafs for a short axial ZN-S bond in the case of cis-endo-3-propenamid-znTPP derivatives featuring a terminal S-alkyl cysteine residue

Abstract “Extended X-Ray Absorption Fine Structure” (EXAFS) spectroscopy has been used for probing the environment of the Zn2+ cation in three 3-propenamid-Zn tetraphenyporphyrin complexes. The lack of evidence for a short axial bond of the zinc atom to the sulfur atom of the cysteine terminal residue of the lateral peptidic chain is discussed, together with the few indications which suggest that a Zn-S interaction, if any, can only be weak and probably long range (4.1 A ?).

Segment coupling in peptide synthesis—II : A simple predictive equation correlating racemization and primary structure

Abstract A predictive equation based on extrathermodynamic assumptions is proposed, that allows the prediction of the degree of epimerization in tripeptide model reactions of condensation of peptide segments as a function of the primary structure. The experimental validation of this equation is presented in the field of the 125 tripeptides containing alanine, leucine, phenylalanine, valine and isoleucine, the prediction requires 13 epimerization measurements on reference reactions. Sixteen statistically chosen predictions are checked experimentally showing a good fit in spite of the drastic basic assumptions needed to set up the equation.

ALKOXYPHOSPHONIUM SALTS. PART 18. COMPARATIVE REACTIVITIES OF FURANOSYLOXYPHOSPHONIUM SALTS

Ohne nahere Angaben wird kurz berichtet, das im Original die Darstellung der Salze (I)-(III) beschrieben ist, die - wie z.B. an (II) aufgefuhrt - mit Arenthiolen in einem SNZ-Prozes zu den Sulfiden wie (IV) reagieren, dagegen mit Ag-tosylat unter Retention zu den labilen Tosylglykosiden wie (V), die in Alkoholen ein Anomerengemisch der Glykoside (VI) liefern.