Publikationsdatum:
2012-07-12
Beschreibung:
By combining enamines, derived from aldehydes and diphenylprolinol trimethylsilyl ether (the Hayashi catalyst), with nitroethenes ((D 6 )benzene, 4-Å molecular sieves, room temperature) intermediates of the corresponding catalytic Michael -addition cycles were formed and characterized (IR, NMR, X-ray analysis; Schemes 3 – 6 and Fig. 1 – 3 ). Besides cyclobutanes 2 , 1,2-oxazine N -oxide derivatives 3 – 6 and 8 have been identified for the first time, some of which are very stable compounds. It may not be a lack of reactivity (between the intermediate enamines and nitro olefins) that leads to failure of the catalytic reactions ( Schemes 3 – 5 ) but the high stability of catalyst resting states. The central role zwitterions play in these processes is discussed ( Schemes 1 and 2 ).
Print ISSN:
0018-019X
Digitale ISSN:
1522-2675
Thema:
Chemie und Pharmazie
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