Chemistry Reference
In-Depth Information
Scheme 2.9
Murakami et al. have utilized bilayer vesicles to study aldolase-type reactions [48].
Formation of
-phenylserine from glycine and benzaldehyde proceeded effectively by
cooperative catalysis of a hydrophobic pyridoxal derivative (
47
) and Zn(
II
) ions in the
bilayer vesicle formed with
32
. The threo isomer was dominantly produced over the
erythro form. A marked enantioselectivity was observed in the co-vesicle of
32
and
35
in combination with
47
and Cu(
II
); the ee for formation of (2S,3R)-
b
-phenylserine over
its enantiomeric (2R,3S)-isomer was 58%. Enantioselectivity also arose with another
bilayer assembly, formed with
32
,
35
, and
37
in the presence of Cu(
II
), where the
(2R,3S) isomer was dominant over the (2S,3R) species in 13% ee. The opposite en-
antioselectivity performed by the second system, as compared with that for
47
, might
reflect a different stereochemical environment around the quinoid intermediate that
allows the attack of benzaldehyde.
b
