Trifluormethyl‐substituierte, heterocyclisch anellierte Pyridine durch intramolekulare Diels‐Alder‐Cycloaddition mit inversem Elektronenbedarf

Abstract

Wu beschreiben eine Synthese von 3-Methylthiod-trifluormethyl-l,2, hiszin (5) aus Trifluordibromaceton (1) und S-Methylthiosemicarbazid. Nucleophile Substitution der Thiomethylgruppe von 5 durch die Alkoxide von 6a-c bzw. durch das ~Amino-l-alkin 11 f W t m den Triazinen 7 bzw. 12, die uber eine Sauerstoff-bzw. eine NH-Briicke mit dem Seitenkettendienophil verkniipft sind Triazine mit Schwefel als Bindeglied zwischen Dien und Dienophil wie 2 h -c werden aus 1 und dem Isothiosemicarbazid-Salz 17 hergestellt. Die Triazine 7,12 und 20 reagieren beim Erhitzen in Chlorben-Zen bzw. Diphenylether zu den muen kterocyclisch anellierlen Pyridinen 8-10,13 und 23-25. Wie wir kiirzlich fanden", entstehen nach der Reaktionsfolge 1 + 2 -) 4 + 5 die konstitutionsisomeren trifluormethylsubstituierten Triazine 4 und 5 im Verhiiltnis 9 5 :~~) . F3C, /CHBrZ C II 0 **) H e m Prof. Dr. K . Dehnicke mit den besten Wiinschen zum 60. Geburtstag gewidmet. giert. Erst anschlieknd kondensiert die Ketofunktion von 2 8 B 10 Schema 2

Diels–Alder Reaction in the Synthesis of Fluorinated (Hetero)Aromatic Compounds

“…Similarly, tricyclic compounds 102 and 103 (from corresponding phenols) and fused pyridines 104 (from corresponding amines) were obtained (Scheme ). Later a similar approach was applied for the synthesis of S ‐containing analogues of compounds 101 …”

“…Later a similar approach was applied for the synthesis of S-containing analogues of compounds 101. [42] Scheme 38. Synthesis of fused CF 3 -containing heterocycles 101-104 by intramolecular Diels-Alder reaction.…”

Direct Synthesis of Imines from gem-Dibromomethylaryl Derivatives: Application to Unsymmetrically Substituted Bipyridine Frameworks

“…Examples for the preparation of an imino compound from molecules where the aldehyde function is masked in the form of a gem -dibromomethyl derivative appeared to be rare and not specifically designed for preparative purposes . However, in some cases, the intermediate imino derivative is postulated to undergo an intramolecular rearrangement, leading to substituted heterocycles such as pyrazines, benzopyrazines, triazines, benzimidazoles, and elaborated poly-heteroaromatic derivatives . As a result of our recent interest in the design of ligands for complexation of lanthanide(III) cations, we have been interested in the reactivity of gem -dibromomethyl-functionalized aromatic compounds. − The scope of application was investigated with dibromomethylbenzene and 6-bromo-5‘-dibromomethyl-2,2‘-bipyridine with various primary aliphatic amines, polyamines, and aniline derivatives.…”

Fluorinated Triazines

“…A synthesis of 3-methylthio-5-trifl uoromethyl-1,2,4-triazine 30 was described using dibromotrifl uoroaceton 3 and S-methylthiosemicarbazide 27 as starting materials (Scheme 15 ) [ 23 ]. The synthesis of 3-methylthio-6-trifl uoromethyl-1,2,4-triazine 31 was achieved by using trifl uoropyruvaldehyde 28 and S-methylthiosemicarbazide 27 as starting materials (Scheme 15 ) [ 24 ].…”