Academic Journal
Synthesis and Thermolysis of a Chiral, Non-Racemic Iminoaziridine
| العنوان: | Synthesis and Thermolysis of a Chiral, Non-Racemic Iminoaziridine |
|---|---|
| المؤلفون: | Quast, Helmut, Schmitt, Edeltraud, Schäfer, Peter, Heller, Eberhard, Aldenkortt, Sven |
| سنة النشر: | 1994 |
| المجموعة: | Würzburg University: Online Publication Service |
| مصطلحات موضوعية: | ddc:540 |
| الوصف: | The 2-halo imidoyl chlorides 7 are obtained from the amide 5 and the 2-halo amides 6 by the action of phosphorus pentachloride and thionyl chloride, respectively. Non-racemic (S)-6a is converted into 7a which is racemic, however. The reaction of Lawesson's reagent with 6a furnishes the diastereomeric 1,3.2-thiazaphospholidine derivatives 15. Treatment of (S)-6a (98% eel with methyl triflate affords 2-chloro imidate 8 (95% eel which reacts with methanamine in the presence of methanammonium chloride to yield the 2-chloro amidine (S)-9a (90% eel. The 2-halo imidoyl halides 7a and b react with methanamine to produce the 2-halo amidines 9a and b. - Strong bases, e.g. potassium tert-butoxide or sodium hydride in the presence of catalytic amounts of tertbutyl alcohol, eliminate hydrogen chloride or bromide from the 2-halo amidines 9a and band (S)-9a to yield mixtures of Recently, we demonstrated that the formation of the chiral non-racemic aziridinone (R)-2 from the a-chloro amide (5)-1 by base-promoted dehydrochlorination[2) as well as the nucleophilic cleavage of the N-C(3) bond of (R)_2[3,4) occur with inversion of configuration, thus excluding the intervention of achiral (acyclic) intermediates. In the temperature range of lOO-170°C, however, slow racemization accompanies the thermolysis of (R)-2 and indicates the existence of an achiral or a racemic transient, e. g. (M)-3 + (P)-3. Indeed, high-level quantum-chemical calculations reveal that an activation energy of (170 ± 25) kJmol- 1 is required for the unimolecular ring opening of the parent aziridinone which affords a species of high diradical character[41. Subsequently, the unstable N-phenylaziridinone invoked in the decomposition of the (5)-2-bromopropananilide anion was shown to react with tert-butylamine or dimethylformamide with inversion of configuration at C(3)[51. Thus, the stereochemical evidence in the series of 3-alkylaziridinones excludes achiral (acyclic) aziridinone isomers as intermediates at low tempera tures [6J. Similar stereochemical studies ... |
| نوع الوثيقة: | article in journal/newspaper |
| وصف الملف: | application/pdf |
| اللغة: | English |
| Relation: | https://opus.bibliothek.uni-wuerzburg.de/frontdoor/index/index/docId/3226; urn:nbn:de:bvb:20-opus-38298; https://nbn-resolving.org/urn:nbn:de:bvb:20-opus-38298; https://opus.bibliothek.uni-wuerzburg.de/files/3226/Heller_Synthesis.pdf |
| الاتاحة: | https://opus.bibliothek.uni-wuerzburg.de/frontdoor/index/index/docId/3226 https://nbn-resolving.org/urn:nbn:de:bvb:20-opus-38298 https://opus.bibliothek.uni-wuerzburg.de/files/3226/Heller_Synthesis.pdf |
| Rights: | info:eu-repo/semantics/openAccess |
| رقم الانضمام: | edsbas.1BF2E94C |
| قاعدة البيانات: | BASE |
| الوصف غير متاح. |