The Nobel trail of Vincent du Vigneaud.

The Nobel Prize for chemistry of 1955 was awarded to Vincent du Vigneaud. After a brief outline of his career and accomplishments, some archive material related to this decision of the Royal Swedish Academy of Sciences is presented. Other archive studies have shown that du Vigneaud was also considered for the corresponding prize in physiology or medicine.

Acidity of di- and triprotected hydrazine derivatives in dimethyl sulfoxide and aspects of their alkylation.

The pK(a) values in DMSO for 22 di- and triprotected hydrazine NH acids and two monosubstituted hydrazines have been determined using potentiometric titration. The results of density functional theory calculations at the B3LYP/6-311+G level of gas-phase acidities of a representative selection of mono-, di-, and trisubstituted hydrazines are compared with both the relevant published and novel experimental titration data. In the course of this work, a rough estimation of the pK(a) value of hydrazine in DMSO (ca.

Synthesis and utilization of 13C and 15N backbone-labeled proline: NMR study of synthesized oxytocin with backbone-labeled C-terminal tripeptide amide.

The 13C and 15N backbone-labeled proline was prepared using Oppolzer's method based on application of a sultam as chiral auxiliary. This isotopomer was used in the synthesis of the 13C, 15N backbone-labeled C-terminal tripeptide amide fragment of neurohypophyseal hormone oxytocin. Finally, this tripeptide amide was coupled by segment condensation with N-Boc- or N-Fmoc-tocinoic acid, followed by N-deprotection with TFA or piperidine.

Reagent for synthesis of secondary amines by two consecutive N-alkylations and its application to orthogonally protected spermidine.

A novel reagent, tert-butyl 2-naphthalenesulfonylcarbamate, has been designed to allow the stepwise synthesis of secondary aliphatic amines by two consecutive N-alkylations with intermediate Boc-cleavage and final desulfonylation under mild and experimentally convenient conditions. Its application was demonstrated to make an orthogonally protected spermidine derivative, suitable for further selective modification. Each individual step, including the final cleavage of 2-naphthalenesulfonyl to provide the secondary amine nitrogen, took place in high yield.

Solid phase synthesis of partially protected tocinoic acid: optimization with respect to resin and protecting groups.

A few solid phase and solution approaches of good repute were applied in parallel with the aim to provide optimized routes to Boc- and Fmoc-tocinoic acid (3a and 3c) and the corresponding Tyr(Bu(t)) derivatives (3b and 3d). Boc-tocinoic acid is known to couple with tripeptide amides to give substituted oxytocin precursors in high yields, requiring only Boc-cleavage to furnish the corresponding hormone analogs with minimal loss of material. For comparison, two protected linear hexapeptides (2a and 2b) were prepared on three polystyrene supports, two with acid-labile handles and one a conventional chloromethylated resin, in yields of 62-82 and 58-76%, respectively.