Propiniminium‐Salze: Ambifunktionelle Reaktivität gegenüber S‐ und N‐Nucleophilen

Abstract

Propyne Iminium Salts: Ambifunctional Reactivity towards Sulfor and Nitrogen NucleophilesPropyne iminium ions 2 s -d have been studied by both ab initio (3-21G//3-21G for 2a) and MNDO calculations (2s-d). It is found that the amino group stabilizes the propargyl cation structure at the expense of the allenyl cation structure. Furthermore, the highest positive charge density is located at the amino-substituted carbon atom. -Reactions of 2-propyne iminium triflates 6a, b with thiols, thiolates, morpholine, lithium morpholide, and phenylhydrazine have been investigated. C-1 attack at 6, expected under kinetically controlled conditions, is observed in a few cases only. In all other cases, products resulting from C-3 attack takes place leading either to 1.3-donorsubstituted allenes (8, 10, 12) in the absence of proton sources or to their C-2-protonated forms (9, 11, 13-15) otherwise.kurzlebige kationische Zwischenstufen verlaufenden Umlagerung von Propargyl-Derivaten in Allene, in mechanistisch modifizierter Form auch bei der Konkurrenz von sN2-und SN2'-Reaktionen an neutralen Propargyl-Verbindungen5'.Wir berichten hier iiber einige nucleophile Additionen an Propiniminium-Ionen des Typs 2 in Verbindung mit MORechnungen zum Bindungszustand und zur Ladungsverteilung in diesen Systemen.

Reaction of arylhydrazines with an α-alkynyl-carbonylic compound: an unexpected hydration reaction

“…As we had expected, the two arylhydrazones 1.1 and 1.2, were obtained by a classically reported methodology, although the synthesis of entry 1.1 was previously reported by Maas et al, by means of the reaction of a 2-propyne iminium triflate with phenylhydrazine. 7 These compounds were identified by their spectroscopic data, mainly from those that reveal both the alkyne and imine functions, and from the corresponding molecular ion by EIMS.…”

Synthesis and reactivity of 3-(dialkylamino)allenyl phosphonium salts. PPh3-mediated synthesis of pyrroles from propyne iminium triflates

“…In some cases, we have gone one step further and have not even isolated the (also moisture-sensitive) iminium salts 1; rather, the multi-step synthesis of pyrroles 10 from enaminoketones 9 has been performed in one pot without isolation of any reaction intermediates. Although the yields of pyrroles 10 were only moderate in most cases, we have not been able to isolate any other product; however, products from the hydrolysis of intermediate allenes (see above) could be detected by 1 H NMR septroscopy in most of the crude reaction mixtures.…”

“…Addition of HOTf to this mixture led to an increase of 5d but full conversion was not achieved. NMR data of 5d: 1 …”

Thioamides and Thioformamides for Sequential Reactions with Organolithium and Grignard Reagents

“…Furthermore, alkynyl S,N-acetal 8 derived from 6g slowly underwent 1,3-rearrangement, and after 24 h, the ratio between 8 and 9 changed from 97:3 to 17:83. 17 The reaction in eq 1 was then extended to thioiminium salts derived from thioformamides (eq 3). Methylation of thioformamide 10a with MeOTf was complete within 30 s to afford thioiminium salt 11a, and to the salt 11a was then added lithium acetylide 3d.…”