Modular Bis(oxazoline) Ligands for Palladium Catalyzed Allylic Alkylation: Unprecedented Conformational Behaviour of a Bis(oxazoline) Palladium η3-1,3-Diphenylallyl Complex
✍ Scribed by Miquel Angel Pericàs; Cristina Puigjaner; Antoni Riera; Anton Vidal-Ferran; Montserrat Gómez; Francisco Jiménez; Guillermo Muller; Mercè Rocamora
- Publisher
- John Wiley and Sons
- Year
- 2002
- Tongue
- English
- Weight
- 286 KB
- Volume
- 8
- Category
- Article
- ISSN
- 0947-6539
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✦ Synopsis
New families of enantiopure bis(oxazolines) with 4,5-trans (5 a-g) or 4,5-cis (6 c) stereochemistry at the individual rings have been prepared in high yield. Their eta(3)-allyl palladium complexes (8 a-g, 9 c and 10) have been used as catalytic precursors in allylic alkylation reactions with excellent enantioselectivities (up to 96 %) for the trans oxazoline derivatives, while Pd/6 c system was inactive. NMR studies on palladium eta(3)-1,3-diphenylallyl intermediates (11 a, c and e) showed the presence of syn/syn- and syn/anti-allyl isomers in solution; this resembles the first example of eta(3)-eta(1)-eta(3) isomerism in Pd allylic complexes containing bis(oxazolines) derived from malonic acid.