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Push–pull alkenes from cyclic ketene-N,N′-acetals: a wide span of double bond lengths and twist angles
- Source :
- Tetrahedron. 66:2919-2927
- Publication Year :
- 2010
- Publisher :
- Elsevier BV, 2010.
-
Abstract
- Push–pull alkenes can be quickly accessed by cyclic ketene-N,N′-acetal chemistry. A number of push–pull structures with a wide span of double bond lengths and twist angles were synthesized from the reactions of (1) N,N′-dimethyl cyclic ketene-N,N′-acetals with isocyanates, (2) the products from (1) with isocyanates, (3) 2-methylimidazoline and 2-methyl-1,4,5,6-tetrahydropyrimidine with diacid chlorides, (4) 2-methylimidazoline, and 1,2-dimethyl-1,4,5,6-tetrahydropyrimidine with benzoyl chlorides, and (5) 1,2-dimethylimidazoline and 1,2-dimethyl-1,4,5,6-tetrahydropyrimidine with aryl isocyanates. These reactions proceed under very mild conditions and give moderate to excellent yields. X-ray crystallographic analysis of eight pxush–pull alkenes indicates that the central double bond lengths and twists are sensitive to the ring sizes (5 or 6), ring structures (fused or non-fused), electron donating and withdrawing strengths of pushing and pulling portions, respectively, number of electron pushing or pulling groups and substituent steric effects.
Details
- ISSN :
- 00404020
- Volume :
- 66
- Database :
- OpenAIRE
- Journal :
- Tetrahedron
- Accession number :
- edsair.doi...........efa36300bc14fbc9f497b78b7f61d272