Mloston, Grzegorz and Urbaniak, Katarzyna and Domagala, Malgorzata and Pfitzner, Arno and Zabel, Manfred and Heimgartner, Heinz (2009) Thermal [2+3]-Cycloadditions of trans-1-Methyl-2,3-diphenylaziridine with C = S and C = C Dipolarophiles: An Unexpected Course with Dimethyl Dicyanofumarate. HELVETICA CHIMICA ACTA, 92 (12). pp. 2631-2642. ISSN 0018-019X,
Full text not available from this repository. (Request a copy)Abstract
The thermal reaction of trans-1-methyl-2,3-diphenylaziridine (trans-1a) with aromatic and cycloaliphatic thioketones 2 in boiling toluene yielded the corresponding cis-2,4-diphenyl-1,3-thiazolidines cis-4 via conrotatory ring opening of trans-la and a concerted [2+3]-cycloaddition of the intermediate (E,E)-configured azomethine ylide 3a (Scheme 1). The analogous reaction of cis-1a with dimethyl acetylenedicarboxylate (5) gave dimethyl trans-2,5-dihydro-1-methyl-2,5-diphenylpyrrole-3,4-dicarboxylate (trans-6) in accord with orbital-symmetry-controlled reactions (Scheme 2). On the other hand, the reactions of cis-1a and trans-la with dimethvl dicyanofumarate (7a), as well as that of cis-1a and dimethyl dicyanomaleate (7b), led to mixtures of the same two stereoisomeric dimethyl 3,4-dicyano-1-methyl-2,5-diphenylpyrrolidine-3,4-dicarboxylates 8a and 8b (Scheme 3). This result has to be explained via a stepwise reaction mechanism, in which the intermediate zwitterions 11a and 11b equilibrate (Scheme 6). In contrast, cis-1,2,3-triphenylaziridine (cis-1b) and 7a gave only one stereoisomeric pyrrolidine-3,4-dicarboxylate 10, with the configuration expected on the basis of orbital-symmetry control, i.e., via concerted reaction steps (Scheme 10). The configuration of 8a and 10, as well as that of a derivative of 8b, were established by X-ray crystallography.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | 1,3-DIPOLAR CYCLOADDITION REACTIONS; AZOMETHINE YLIDES; THIOCARBONYL YLIDES; SUBSTITUTED ETHYLENES; ELECTRON-TRANSFER; THIOKETONES; AZIRIDINES; CHEMISTRY; CRYSTAL; ALKENES; |
| Subjects: | 500 Science > 540 Chemistry & allied sciences |
| Divisions: | Chemistry and Pharmacy > Institut für Anorganische Chemie > Chair Prof. Dr. Arno Pfitzner |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 12 Oct 2020 09:07 |
| Last Modified: | 12 Oct 2020 09:07 |
| URI: | https://pred.uni-regensburg.de/id/eprint/29736 |
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