Advices For Studying Organic Chemistry

BH B

OBn OBn

B

OBn

H

NB-EnantrideTM

Li

nopol benzyl ether NB-EnantraneTM

t-BuLi

3) Reagents derived from LiAlH 4 and chiral amines have also been developed.

4) Often it is necessary to test several reaction conditions in order to achieve

optimal stereoselectivity.

5. Prochirality
   
   
   1. For a given enzymatic reaction only one specific hydride from C4 in NADH is
      transferred.
   
   
   
   

N

HR

HS

R

O

H 2 N

Nicotinamide ring NADH, showing the pro-R and pro-S hydrogens

2) The hydrogens at C4 of NADH are prochiral.

3) Pro-R and pro-S hydrogens:

i) If the configuration is R when the hydrogen is “replaced” by a group of higher

priority than hydrogen it is a pro-R hydrogen.

ii) If the configuration is S when the hydrogen is “replaced” by a group of higher

priority than hydrogen it is a pro-S hydrogen.

3) Pro-chiral center:

i) Addition of a group to a trigonal planar atom or replacement of one of two

identical groups at a tetrahedral atom leads to a new stereocenter ⇒ a

prochiral center.