ISSN:
0947-6539
Keywords:
assymetric substitution
;
cerium reagents
;
enamino ketones
;
regioselectivity
;
synthetic methods
;
Chemistry
;
General Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Stereoselective construction of trisubstituted alkenes has wide applicability to the synthesis of many natual products Specifically, β-disubstituted enones are important functionalized trisubstituted alkene targets. The reaction of organocerium reagents with secondary β-enamino ketones affords β=disubsituted α,β-unsaturated ketones in fairly good yields. This process shows considerable stereoselectivity, and α,β-unsaturated ketones of (E) configuration are predominantly observed. Organolithium-derived cerium reagents display better stereoselectivity than organomagnesium-based ones. The mechanism of the reaction varies with nitrogen substitution: N-phenyl groups give 1,2-addition products, whereas substitution products are observed with N-alkyl groups. When organocerium reagents were used with β-enamino ketones bearing secondary alkyl groups at the nitrogen atom, a lack of reactivity was observed.
Additional Material:
2 Tab.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/chem.1460020802
