Organocopper reactions with allylic acrylates. The preparation of {gamma},{delta}-unsaturated acids and the subsequent transformation to {gamma}-lactones
- Chalmers Univ. of Technology, Goeteborg (Sweden)
The conjugate addition of organocopper reagents to {alpha},{beta}-unsaturated ketones and esters is a commonly used method for carbon-carbon bond formation. When this is applied on allylic enoates, the primary ester enolates/silyl ketene acetals from the addition undergo Claisen rearrangement at room temperature to afford diastereomeric mixtures of {gamma},{delta}-unsaturated acids after hydrolytic work-up. The E/Z ratio for the primary ester enolates/silyl ketene acetals controls the erythro:threo ratio for the {gamma},{delta}-unsaturated acids. The present work is an investigation of different organocopper reagents (e.g. RCu(LiI)-TMSI) in reactions with crotyl and cinnamyl acrylate. The diastereomeric ratio is strongly influenced by the organocopper reagent (RCu(LiI) vs R{sub 2}CuLi(LiI)) as well as the additive (TMSCl vs TMSI). Subsequent iodolactonization of the {gamma},{delta}-unsaturated acids followed by reduction give trisubstituted {gamma}-lactones in good overall yields.
- OSTI ID:
- 250125
- Report Number(s):
- CONF-9508100--
- Country of Publication:
- United States
- Language:
- English
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