New Methods for the Synthesis of Peptides

A convenient general method for synthesis of Nα‐ or Nω‐dithiasuccinoyl (Dts) amino acids and dipeptides: application of polyethylene glycol as a carrier for functional purification*

“…Finally, as reported elsewhere in this journal (9), the library of protected amino acid derivatives thus prepared has been evaluated for orthogonal solidphase peptide synthesis and shown to meet the exacting criteria of this field. (66). The corresponding free acids were obtained either by direct Schotten-Baumann acylation (67), or by removal of the ester as described in the literature (65-67).…”

“…The title compound was prepared on a 6 mmol scale by acid hydrolysis of the corresponding methyl ester 7b according to Kollonitsch et al (66); 85% yield after recrystallization from hot CHCl,, m.p. 7678" [lit.…”

Phenylthiocarbamate orN-Carbothiophenyl Group Chemistry in Peptide Synthesis and Bioconjugation

“…7 The reaction presumably proceeds through the formation of a thiocarbamate sulfoxide intermediate 12 , 8,9 which is further oxidized by the peracid into thiocarbamate sulfone 13 . The latter decomposes spontaneously in the presence of water, with production of carbon dioxide and benzenesulfonic acid 14 .…”

Thiocarbonates as Blocking Groups for the Synthesis of Partial Esters of Carbohydrates

“…The (al1tylthio)carbonyl2 group, R-S-C-, has been utilized as a protective radical for amino groups in peptide synthesis (2). The (benzy1thio)carbonyl derivative of methyl-LY-D-glucopyranoside was encountered (3) as an intermediate during the two-step removal of the xanthate group from methyl 2,3,4-tri-0-benzoyl-G-0-(be1~zylthio)thiocarbonyl-oc-~-glucopyranoside, and was shown to be readily deconlposed by mild oxidation, the parent alcohol being liberated.…”

“…The properties of the thiocarbonate group which contribute to its value as a blocking agent are the following: (1) (benzy1thio)carbonyl chloride, prepared by the action of 1 mole of phosgene on benzyl lnercaptan i11 aqueous alltali (3, 9), call be purified by distillation and is stable during storage; (2) Although (al1cylthio)carbonyl derivatives other than the benzyl analogue are prepared with equal ease, use has bee11 confined chiefly t o the (benzylthio)carbo~~yl ester in this laboratory.…”