Orthoamides. IL. Reactions of Orthoamide Derivatives with Sulfur and Selenium, Syntheses of 1,3‐Thiazole‐ und 1,3‐Selenazole Derivatives N,N‐Dimethylformamide acetal reacts with elemental selenium to give a mixture of selenocarbonic acid derivatives 2 and 3, which can be converted to the pure N,N‐dimethylcarbamidic acid Se‐methylester 2 by treatment with methyl iodide. Analogously from the orthoformic acid derivatives 5 and 6 and selenium the N,N,N′,N′‐tetramethyl‐selenurea 7 can be prepared. In the reaction of 12 with elemental sulfur and selenium the amidines 14 and 15, respectively, are formed. By treatment of 14 and 15 with α‐halogenated carbonyl compounds and triethylamine the 1,3‐thiazoles 18 and 1,3‐selenazoles 19 can be prepared. The synthesis of the propynoic acid orthoamide 26b is described. 26b reacts with the guanidinium salt 24b to give the bis‐orthoamide of butynedioic acid 20b. Other orthoamides of butynedioic acid 20b–20e can be synthesized from the orthoamide 20a by transamination. The thiolation of the orthoamides affords the bisamidinium‐dithiolates 21a–c, which can be alkylated to give the bisamidinium salts 27. By treatment with α‐halogene carbonyl compounds and triethylamine the dithiolates 21a–c are cyclized to give thieno [3,2b] thiophenes 28a–n. The quadrupoles 21 undergo cycloadditions with dimethyl‐butynedioate which afford the bis(3H‐thiophene‐2‐ylidenes) 29a–c. Treatment of 29a with methyl tosylate gives rise to the dithiophene 30a. The dithiophene 30b can be obtained by heating 21b with dimethylbutynedionate.

Gold berichtete im Jahr 1960 über eine einfache Synthese azavinyloger Formamidiniumsalze aus Cyanurchlorid und N,N-Dialkylformamiden sowie über die Darstellung eines Azavinylogen des N,.Der Bildungsmechanismus der azavinylogen Formamidiniumsalze wurde aufgeklärt [3 -5]; dabei wurde eine Reihe weiterer Synthesen für derartige Salze gefunden. Die Chemie der azavinylogen Formamidiniumsalze wurde auch schon zusammenfassend behandelt [6]. Im Rahmen unserer Arbeiten über Orthoamide und Iminiumsalze haben wir immer wieder auch über Formamidiniumsalze 1 und azavinyloge Orthoameisensäurederivate 2 -4 berichtet [7a -h]:Abstract. The azavinylogous aminalester 3 reacts with primary amines to give amidines 5 and 6. In the reaction of 3 with aniline the azavinylogous amidine 7 is produced additionally to the amidine 5c. Ethylendiamine is formylated at both aminogroups, the bis-amidine 8 thus formed is transformed to the salts 9a,b. Benzoxazole and benzimidazole can be prepared from 3 and o-aminophenol and o-phenylenediamine, resp. Carboxylic acid amides, urea, thiourea, aromatic acid hydrazides 17 and the sulfonylhydrazide 19 are formylated by 3 at nitrogen to give N-acylated formamidines 14, 16, 18, 20. From 3 and aliphatic acid hydrazides 17 and alkylhydrazines, resp., can be obtained 1,2,4-triazole 21 and 1-alkyl-1,2,4-triazoles 22a,b, resp. N,N-Dimethylcyanacetamide (32) reacts with 3 and the orthoamide 4a, resp., to give a mixture of the formylated compound 34 and the amidine 33. The reaction conditions are of low influence on the ratio in which 33 and 34 are formed. The orthoamide 4b and 32 react to afford a mixture of the amidine 35 and the enamine 36. Hydrogensulfide acts on 3 giving N,N-dimethylthioformamide (37). From 3 and 1-alkynes 41 can be prepared the amidines 42. ⊕ ⊕ ⊕ ⊕ ⊕ Ó 682

Preparation of Organic Dications by Protonation of Iminium‐Salts. – NMR‐Spectroscopic Evaluation of the Topomerisation Barriers in the Bis(dimethylamino)‐dimethylammonio‐carbeniumion 1,3‐Bis(dimethylamino)‐2‐aza‐2‐propenylium‐chloride (4a) is protonated by inorganic acids as HCl, HBr, HI, H2SO4, HBF4 and HClO4 to give the corresponding 1,3‐bis(dimethylamino)‐2‐azapropan‐1,3‐diylium‐salts (7a–f) which are isolated and characterized by elemental analysis and their 1H‐NMR‐spectra. N, N, N′, N′, N″, N″‐Hexamethylguanidinium‐chloride (5a) can be protonated only by super acid systems e.g. HFSO3/SbF5. The dication thus formed presents 3 topomerisation barriers. Two of them are explained as restricted rotations, whereas the third is assumed to be a frozen torsional vibration.

Condensation reactions of azavinylogue orthoamides 5a and 6a with CH2‐acidic compounds are described. Reaction products are formylated ‐ or azavinylogue formylated compounds 8 and 9 resp. The condensation reactions of 5a can be enhanced by addition of trimethyl borate. Under these conditions the formylations reaction‐leading to compounds of type 8 ‐ is preferred.

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