Synthesis and Hydrolysis of [Alkenyl(alkoxy)carbene]manganese Complexes: Evidence for a Transient Allylic Intermediate on the Way to α,β-Unsaturated Aldehydes
✍ Scribed by Carole Mongin; Yannick Ortin; Noël Lugan; René Mathieu
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- English
- Weight
- 285 KB
- Volume
- 1999
- Category
- Article
- ISSN
- 1434-1948
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✦ Synopsis
A variety of alkenylcarbene complexes [CpЈ(CO) 2 Mn= with water affords the α,β-unsaturated aldehyde complexes [CpЈ(CO) 2 Mn(η 2 -RCH=CHCHO] (5), from which the C(OEt)CH=CHR] (3) (CpЈ = η 5 -MeC 5 H 4 ) was obtained in a straightforward manner upon aldol condensation of aldehydes RC(H)=C(H)C(H)O (6) were displaced by acetonitrile. The intermediate aldehyde complexes are [CpЈ(CO) 2 Mn=C(OEt)CH 3 ] (1) with aromatic and α,βunsaturated aldehydes RC(H)O (2). The reaction is totally shown to result from the hydrolysis of a transient cationic πallyl species [CpЈ(CO) 2 Mn(η 3 -RCHCHC(OEt)H] + ([4] + ) stereoselective, giving (E)-or (all-E)-alkenylcarbenes only. The protonation of 3 at low temperature followed by reaction formed upon protonation of 3.