(Benzylthio)‐ und (Arylthio)‐substituierte Nitril‐ylide: Thermische Erzeugung und Reaktionen

Abstract

Thermal Generation and Reactions of (Benzy1thio)-and (Ary1thio)-Substituted Nitrile YlidesThermolysis of 4-(benzy1thio)-and 4-(ary1thio)-1,3-oxazol-5(2H)-ones 6, at 1 10-1 55" in the presence of dipolarophiles with activated CEC, C=C, C=O, C=S, and N=N bonds, led to 5-membered cyclo-adducts and C 0 2 (el: Schemes 3, 5-7). Heating 6a and 6c in the presence of ethyl propiolate yielded ethyl quinoline-3-carboxylate (19) and ethyl pyridine-3-carboxylate (22), respectively (cf. Scheme 8 ) . These results are rationalized on the basis of the intermediate formation of thio-substituted nitrile ylides of type 7 (cf. Scheme 2 ) , which undergo regioselective 1,3-dipolar cycloadditions with reactive dipolarophiles. In the absence of such a dipolarophile, the nitrile ylides isomerize uia a [1,4]-H shift to give 2-aza-1,3-butadienes of type 20. The latter are trapped in a Diels-Alder reaction with ethyl propiolate (cf. Scheme 8).

Chemoselectivity of the Reactions of Diazomethanes with 5‐Benzylidene‐3‐phenylrhodanine

“…Elemental analyses and mass spectra indicated that the isomeric compounds were CH 2 adducts of 2. Furthermore, the 13 C-NMR spectra evidenced that in both products the C¼S and the C¼O group were retained, i.e., the reaction of 7a had occurred at the benzylidene group. Whereas the spectroscopic data of the minor product were in accordance with the spirocyclic structure 9a, the major product exhibited the signals of a Me group at 2.76 ( 1 H) and 21.8 ( 13 C) 2 ) (Scheme 1).…”

“…Evaporation of the solvent and washing of the residue with boiling hexane gave 11 in 93% yield (Scheme 1). The structure was confirmed by the 13 C-NMR, elemental-analysis, and MS data, and was established by X-ray crystallography (Fig. 3).…”

“…Because the 13 C-NMR data of our compound did not correspond to those described in the literature [28], we synthesized 10 independently from benzophenone and NH 2 NH 2 · H 2 O in EtOH at 1608 according to [29] and from 7c according to the procedure described in [27b]. The 13 C-NMR data given in [28] correspond to those of benzophenone.…”

“…1) as dipolarophiles. All reactions with nitrile imines [12], nitrile ylides [12] [13], thiocarbonyl ylides [14], carbonyl ylides [15], azomethine ylides [16], and diazo compounds [17] occurred at the C¼S bond leading to spirocyclic products. Similarly, organic azides and benzonitrile oxide underwent a cycloaddition with the C¼S bond of 1, but the initially formed spirocyclic products were not stable, and the corresponding 1,3-thiazol-5(4H)-imines [18] and 1,3-thiazol-5(4H)-one [19], respectively, were obtained.…”

N‐(1,3‐Thiazol‐5(4H)‐yliden)amine aus 1,3‐dipolaren Cycloadditionen von Aziden mit 1,3‐Thiazol‐5(4H)‐thionen

“…Erhitzen der CI -(Acylamino)-thioamide 10 und AlC1, in Toluol in geringer Ausbeute 1,3-Thiazol-5(4H)-imine 11 (Schema 4 ) im Gemisch mit weiteren Cyclisierungsprodukten [27]. Neben Nitrilium-betainen (s. [18][19][20][21]) gehen offensichtlich auch Azide, d. h. Vertreter der Diazonium-betaine, rnit der (C=S)-Gruppe von 2 1,3-dipolare Cycloadditionen ein. Nach Sustmann [28] Mit den berechneten AO-Koeffizienten und Energien der Grenzorbitale (Fig, 1 ) lassen sich auch die iibrigen bisher beobachteten Cycloadditionen von 1,3-Thiazol-5(4H)-thionen befriedigend erklaren (Fig.…”