Asymmetric ethylation of aromatic aldehyde by diethylzinc in the presence of chiral auxiliaries derived from (S)-[4-HOC6H4CH2CH(NH2)CPh2OH]
✍ Scribed by James L. Wardell; Attera Worayingyong
- Publisher
- John Wiley and Sons
- Year
- 1995
- Tongue
- English
- Weight
- 398 KB
- Volume
- 9
- Category
- Article
- ISSN
- 0268-2605
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✦ Synopsis
A comparative study has been carried out on enantioselective ethylation of aromatic aldehydes (ArCHO) by diethylzinc (EGZn) in the presence of catalytic amounts of (S)-[4-HOC,H4CH,CH(NH2)CPh,0H] (1) or chiral auxiliaries derived from (1). Various procedures have been adopted; these involved (i) different sequences of addition of the reagents ArCHO, Et,Zn and (l), and (ii) use of titanium(1-V)isopropoxide [Ti(OPr'),] or the boranetetrahydrofuran addition compound (BH, THF) as additional reagents. In all but one of the procedures adopted, (S)-ArCH(0H)Et was selectively formed; enantiomeric excess values up to 87% were obtained.