Synthesis of oxytocin and related diastereomers deuterated in the half-cystine positions. Comparison of solid-phase and solution methods

Abstract

Ultraviolet spectra were recorded on a Cary 14 double-beam recording spectrophotometer. Infrared spectra were taken on a Beckman IR-10 spectrophotometer. Mass spectra were determined on a Hitachi Perkin-Elmer RMU-6D single-focusing mass spectrometer operating at 70 eV. Circular dichroism curves were recorded in n-pentane at room temperature on a Cary 61 spectropolarimeter. Optical rotations were determined on a ETL-NPL (Ericsson Telephone Unlimited) automatic polarimeter. (19) H. Morrison, J. Chem. Educ., 44, 161 (1967). (20) Multiple! collapses to an AB quartet (J = -20 Hz) when Irradiated at 5.6 ppm.(21) Only a carbon-13 nmr spectrum of a 1:1 mixture of 16 and 17 was obtained:

Interactions of oxytocin with bovine neurophysins I and II. Use of carbon-13 nuclear magnetic resonance and hormones specifically enriched with carbon-13 in the glycinamide-9 and half-cystine-1 positions

“…TVG-Tosyl protection was used for arginine. Labeled S-benzyl-DL-[2-13C]cysteine was added at a much reduced excess (1.6 equiv) as previously reported (Upson and Hruby, 1976;Spatola et al, 1974).…”

Synthesis of specifically deuterated S-benzylcysteines and of oxytocin and related diastereomers deuterated in the half-cystine positions

“…(20). 45 Analysis by the Folin-Lowry method54 showed a small by-product peak at Rj 0.61, and a large, poorly resolved peak at Rj 0.38-0.20 of the incompletely separated diastereomeric oxytocin derivatives. 9 The preparation was done on a 1.5-mmol scale, which required 3.19 g of the resin 19.…”

“…44 The isomers were separated from each other and from by-products by partition chromatography on Sephadex G-25 using the solvent system l-butanol-3.5% HOAc in 1.5% aqueous pyridine (1:1).45 At Rf 0.32, the peak for the hemi-D-cysteine derivatives of oxytocin appeared, and at Rf 0.24, the peak for the oxytocin derivatives appeared, both Rf values in close agreement with our previous experience with diastereomeric mixtures. 45 The diastereomers were isolated and further purified by gel filtration on Sephadex G-25 using 0.2 N HOAc as eluting solvent. The purity of the products was checked by thin layer chromatography in three solvent systems, quantitative amino acid analysis, and optical rotation determination.…”

Comparative use of benzhydrylamine and chloromethylated resins in solid-phase synthesis of carboxamide terminal peptides. Synthesis of oxytocin derivatives

“…The protected specifically deuterated amino acid Boc-S-benzyl-DL-[a-2H1]cyste-ine19 was used to introduce the TV-terminal amino acid residue (see Experimental Section). The peptide resin Boc-DL-[a-2Hi]Cys(Bzl)-Tyr-Ile-Gln-Asn-Cys(DMB)-Pro-Leu-Gly-NH-resin was treated with anhydrous HF containing 10% anisóle at 20 °C for 1 h, and the residual S-benzyl protecting groups27 were removed by treatment of the peptide material obtained from the HF treatment with sodium in anhydrous liquid ammonia. 28 The peptide was oxidized with 0.01 N KsFe(CN)629 under nitrogen.…”