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

66 Reducing Agents
RH
(TMS) 3 SiH
(TMS) 3 Si
R
R O SMe
S Si(TMS) 3
O SMe
S
R O SMe
S Si(TMS) 3
Scheme 4.3 Propagation steps for the reaction of cyclohexyl xanthate with
(TMS) 3 SiH
variety 2 0 ,3 0 -didehydro-2 0 ,3 0 -dideoxy derivatives of ribonucleosides were prepared.
From a mechanistic point of view, the initial propagation steps are
similar to Scheme 4.3 until the formation of R:, followed by a b-elimination
to give the olefin and a radical fragment that continues the chain by hydrogen
abstraction from the silane.
O
O
PhNHC(S)O
OC(S)NHPh
O
O
(TMS) 3SiH
AIBN, 80 �C
4.3.4 MISCELLANEOUS REACTIONS
O
O
84%
O
O
(4.39)
Isocyanides can be reduced to the corresponding hydrocarbon by (TMS) 3SiH
[43]. The reaction can be considered a smooth route for the deamination
of primary amines, through the preparation of isocyanides via formylation
and dehydration. The efficiency of the reduction is independent from the nature
of the alkyl substituent. That is, primary, secondary, and tertiary isocyanides
at 80 8C gave the corresponding hydrocarbons in good yields. Two examples
are given in Reactions (4.40) and (4.41) [1,43]. The key step for these chain
reactions is expected to be the fragmentation of the intermediate radical
derived from the fast addition of (TMS) 3Si: radical to the specific substrate
(Table 4.3).