Stereoselective synthesis of substituted 1,2-ethylenediaziridines and their use as ligands in palladium-catalyzed asymmetric allylic alkylation |
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Authors: | Andrea Gualandi |
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Institution: | Dipartimento di Chimica “G. Ciamician”, Universita' di Bologna, via Selmi 2, 40126 Bologna, Italy |
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Abstract: | The double addition of organometallic reagents to fused oxazino-oxazines prepared from glyoxal and (S)-phenylglycinol afforded C2- or C1-symmetric 1,2-ethylenebis(β-aminoalcohols), depending on the nature of the organometallic reagent. This route was modified by the use of (S)-valinol and phenylglyoxal as starting materials, and by reduction of the oxazino-oxazines by diborane. Cyclization of the β-aminoalcohol moieties gave 1,2-ethylenediaziridines bearing one substituent/stereocenter on the ring carbon and one, two or no substituents/stereocenters in the ethylene tether. These bis(aziridines) were used as ligands in the Pd-catalyzed allylic alkylation of dimethyl malonate. It was established that the substituent(s) in the carbon tether and the configuration of the corresponding stereocenters have limited influence on the enantioselectivity. |
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Keywords: | Asymmetric allylic alkylation Aziridine Diastereoselective organometallic reaction Oxazine Palladium |
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