Download Sources of hydride ion

Sources of hydride ion
H
Na+
H
H
B
H
B
H
H
NaBH4
less
reactive
LiAlH4
very
reactive
H
H
Li+
H
H
Al
H
Al
H
H
H
H
Al
D
DIBALH
specially
i ll used
d ffor
ester  aldehyde
diisob t lal min m hydride
diisobutylaluminum
h dride
1
Reduction reactions with
h NaBH4
2
Reduction reactions with
h NaBH4
esters
carboxylic acids
NaBH4
reduction products DO NOT form
amides
3
Reduction of esters with
h LiAlH4
-- LiAlH4 is more reactive th
han NaBH4
4
Reduction of carboxylic acids with LiAlH4
5
Reduction of amides witth
th LiAlH4
6
7
Reduction of esters with
h DIBALH
-- DIBALH is less reactive than LiAlH4
8
Sodium borrohydride
9
Lithium alum
minum hydride
10
DIBALH (i-Bu2AlH)
11
Stereochem
mistry
12
Definition of Re fa
ace and Si face
1
O
Re
C
Si
CH2CH3
H3C
2
3
13
Stereochem
mistry
14
Stereochem
mistry
15
Reactions for ketone/alldehyde
ldehyde – type II:
16
Reactions wiith water
Water adds to an aldehyde or kettone to form a hydrate:
H+
17
Mechanism for acid-cata
alyzed
y
hydrate
y
formation
18
19
20
Reactions wiith
ith alcohols
21
Mechanism for acid-catalyzed ace
etal or ketal formation:
etal
22
Formation of cyclic
y c ketals and acetals
-- act as protecting
g groups
23
Why
yp
protecting
gg
gro
oups?
p
Utilization of protecting groups
g
in synthesis:
24
Protecting
gg
groups
p
25
Protecting
gg
groups
p
26
Reactions wiith
ith thiols
Hg2+
Hg2+
27
Desulfurization replace
p es the C-S bonds
with C-H bonds
28
Reactions of ketones/alde
ehydes with primary amines
ehydes
29
Reactions of ketones/alde
ehydes with 2o amines
ehydes
30