Über die Struktur der Thioamide und ihrer Derivate, XXX¹⁾ N‐Sulfonylthioamide

Abstract

N‐Sulfonylthioamide 4 können durch Umsetzung von Grignardverbindungen 3 mit Sulfonyl‐isothiocyanaten 2 erhalten werden. Durch vergleichende IR‐spektroskopische Untersuchungen (Tabellen 4 und 5 ) und durch Bestimmung der Dipolmomente wurden Aufschlüsse über die Konformation der Verbindungen gewonnen. Acidität (Tabelle 2), Alkylierungsverhalten, UV‐ (Tabelle 3) und IH‐NMR‐Daten werden diskutiert.

On‐resin synthesis of novel arginine‐isostere peptides bearing substituted amidine headgroups

“…Our retrofitted approach toward carrying out this solution‐phase chemistry on the solid support utilized the identical N ‐Pmc substituted thioamides as in our previous report but with a resin‐bound Orn side‐chain playing the role of the amine partner. As such, an assortment of N ‐Pmc thioamides was constructed as previously described to explore the scope and limitations of this methodology (Table ), using a variation on the method of Walter , which we had further optimized. Briefly, Pmc isothiocyanate 1 was treated with a variety of Grignard reagents to afford a series of N ‐Pmc‐substituted thioamides 2a–2i .…”

Comprehensive and Facile Entry into Substituted Amidines via the Condensation of N-Pmc-Substituted Thioamides with Amines Using Mukaiyama Reagent as a Thiophile

“…A variation on the method developed by Walter was used to construct the N-Pmc-thioacetamide (2a) test system, through addition of methylmagnesium bromide to N-Pmc-isothiocyanate 1. 15 In addition to the EDCI thiophile, diisopropylcarbodiimide (DIC), 2-(1H-7azabenzotriazol-1-yl)-1,1,3,3-tetramethyl uronium hexafluorophosphate (HATU), benzotriazol-1-yl-oxytripyrrolidinophosphonium hexafluorophosphate (PyBOP), and 2-chloro-1-methylpyridinium iodide (Mukaiyama reagent) were each evaluated under identical conditions for their ability to promote the desired reaction in both N,N-dimethylformamide and dichloromethane. DIC was immediately excluded because it failed to yield any desired product.…”

“…To fully investigate the scope and limitations of the nowviable amidinylation process, a series of N-Pmc-thioamides was synthesized that allowed a full exploration of steric and electronic effects on the reactivity of thioamide and amine partners. The methodology developed by Walter and Röhr 15 was again used to synthesize a series of N-Pmc-thioamides 2, which were obtained from addition of a series of Grignard reagents to N-Pmc-isothiocyanate 1. Table 1 illustrates the range of aryl and alkyl architecture achievable from this process, comprising a spectrum of steric, functional, and electronic properties.…”

“…20 It was used very successfully as a protecting/activating group in our methodology for the synthesis of substituted guanidines. 15 However, when the Pmc-deprotection of the amidines 3 was attempted, NMR analysis of the crude product mixtures showed only partial Pmc-deprotection took place, even in the presence of scavengers such as HSCH 2 CH 2 SH, thioanisole, phenol, etc., and after long reaction times (data not shown). After some optimization, we found that a 95:5 (v/v) mixture of trifluoroacetic acid and trimethylsilyl trifluoromethanesulfonate allowed complete Pmc-deprotection in all cases.…”

Professor Wolfgang Walter in memoriam

“…Rather, their reactivity was explored comprehensively. Publications on alkylation [27], acylation [28], silylation [29], electrophilic amination [30], sulfenylation [31], and sulfonylation [32] reactions of thiocarbamoyl compounds appeared. Furthermore, the preparation and characterization of sulfuranes [33], a remarkable class of compounds with hypervalent sulfur, was described.…”