110317-87-8Relevant articles and documents
2-Alkylidenimidazolidines - Ketene Equivalents in the Inverse Diels-Alder Reaction
Gruseck, Ursula,Heuschmann, Manfred
, p. 2065 - 2074 (2007/10/02)
2-Alkylideneimidazolidines 1 and 2,4-dienoates 2 form cycloadducts at or below room temperature, which are mildly hydrolysed by dilute acid to form derivatives of 2-cyclohexenone and 1,3-cyclohexadienol.The structures of the cis/trans-disubstituted cyclohexenones 14 and 15 were determined by means of 13C-NMR spectroscopy.The cis/trans ratio can be influenced through the choice of the 2-alkylideneimidazolidines 1.Especially N-phenylsubstituted derivatives form trans products 15 stereoselectively but not stereospecifically.The reason for this selectivity is discussed with regard to the multi-step mechanism of the cycloaddition.Depending on the structure of the starting materials 1 and 2, michael additions and acid-base reactions are observed besides cycloadditions.