"Front Matter". In: Organosilanes in Radical Chemistry - Index of

58 Reducing Agents
To illustrate the efficiency of dechlorination reactions, a few examples have
been chosen from different areas. Reaction (4.16) shows chlorine atom removal
from the 2 0 -position of sugar moiety whereas Reaction (4.17) shows the formation
of a 3-unsubstituted azetidinone [38,39]. The reduction of the dichloride
depicted in Reaction (4.18) represented the key step in the total synthesis of
dactomelynes, a group of natural products isolated from a marine organism.
The use of (TMS) 3SiH at room temperature allowed the monochloride to be
obtained in high yield and stereoselectively (b: a ¼ 13: 1), whereas other radical-based
reducing systems failed [40]. In this respect, the stereoselective reduction
of gem-dichlorides by (TMS) 3SiH and Bu3SnH was previously reported
and evidenced that the silane has a stronger preference than tin to transfer a
hydrogen atom from the less hindered side of the molecule, due to the different
spatial shapes of the two reagents [41].
Cl
Cl
MeO 2 C
BzO
BzO
Cl
O
O
N
Cl
N
O H
H
O
O
H
O
NH
O
OBz
(TMS) 3SiH
AIBN, 80 �C
(TMS) 3 SiH
AIBN, 100 �C
BzO
BzO
O
92%
N
O H
85%
O
N
NH
O
OBz
Cl Cl
Ph (TMS) 3SiH
H
Cl
MeO 2C
Et 3 B, r.t.
H
O
O
H
O
Ph
+
MeO2C 98% (13:1)
Cl
H
H
O
O
H
O
Ph
(4.16)
(4.17)
(4.18)
Under free-radical conditions, the reaction of (TMS) 3SiH with acid chlorides,
RC(O)Cl, gives the corresponding aldehydes and/or the decarbonylation
products depending on the nature of substituent R [42]. The reduction of
1-adamantanecarbonyl chloride is given in Reaction (4.19).