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Syntheses of a Novel Class of 5/6/5‐Heterocycles: Convenient Routes from Aldehydes to Bis(1,3,4‐thiadiazolo)‐1,3,5‐triazinium Halides
Author(s) -
Anders Ernst,
Wermann Kurt,
Wiedel Bernd,
Günther Wolfgang,
Görls Helmar
Publication year - 1998
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/(sici)1099-0690(199812)1998:12<2923::aid-ejoc2923>3.0.co;2-2
Subject(s) - chemistry , pyridinium , electrophile , thiadiazoles , halide , medicinal chemistry , ab initio , alkylation , computational chemistry , proton nmr , carbon 13 nmr , stereochemistry , organic chemistry , catalysis
Novel 5/6/5 heterocycles, 1,3,4‐thiadiazolo[3,2‐ a ]‐1,3,4‐thiadiazolo[3,2‐ d ]‐1,3,5‐triazinium halides 7 , have been synthesized by the reaction of 2‐amino‐1,3,4‐thiadiazoles 6 with either 1‐(haloalkyl)pyridinium halides 4 or N , N′ ‐methylenebis(pyridinium) dibromides 5 . The tricyclic compounds 7 are generated in the course of several successive reaction steps in which specific proton migrations, bond‐breaking and bond‐forming processes occur. The structures 7 have been verified by spectral data ( 1 H and 13 C NMR, MS), X‐ray analysis and ab initio calculations. The latter show that both sp 2 ‐C atoms C(10) and C(12) of 7 are significantly positively charged and, therefore, exhibit electrophilic properties towards the primary amino group of the amino‐thiadiazoles 6 . In the course of a multi‐step reaction cascade of the 6 / 7 mixture, novel multi‐aza/thia heterocycles 8 are formed. The structures of the latter compounds have been confirmed by X‐ray analysis as well as by detailed experimental and theoretical NMR‐spectroscopic studies.