Abstract
In kinetic resolutions of the racemic aldehyde 1 by reaction with
chiral phosphonates of type 2, all of which contain the same
chiral auxiliary in the same enantiomeric form, any of the four
diastereomers 3a, 3b, 4a or 4b can be obtained as the main product
by an appropriate choice of reaction parameters (geometric
selectivities from 66:34 to 98:2, diastereomer ratios between 93:7
and *99:1). The switch in stereoselectivity observed when KHMDS or
NaHMDS is used as base instead of KHMDS/18-crown-6 is rationalized
as resulting from a change in influence of the aldehyde
a-stereocenter from Felkin-Anh-Eisenstein to chelation control.
| Original language | English |
|---|---|
| Journal | Tetrahedron Letters |
| Volume | 38 |
| Issue number | 52 |
| Pages (from-to) | 9035-9038 |
| Publication status | Published - 1997 |