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

134 Unimolecular Reactions
H 3 C + H 3 SiSiH 3
H
H 3 C Si SiH 3
H H
68
H
H H
Si
H 3 C SiH 3
69
‡
‡
H 3 CSiH 3 + SiH 3
Scheme 6.14 Backside and frontside substitution reactions of methyl radical with disilane
example of addition of (TMS) 3SiH to the 1,7-diene 75, which affords the
bicyclized product 76 in an isomeric mixture (1.7:1) of cis- and trans-fused
compounds [30].
72
Br
70
I
Si(SiMe3 ) 3
E
E
Si(SiMe 3 ) 3
(TMS) 3 SiH
AIBN, 80 �C
(TMS) 3 SiH (cat.)
AIBN, 80 �C
(TMS) 3 SiH
AIBN, 80 �C
Si(SiMe 3 ) 3
73, 63%
E
E
71, 88%
75, E = CO 2 Me 76, 52%
Si(SiMe 3 ) 2
(6.14)
+ Si(SiMe3 ) 2 (6.15)
74, 24%
Si(SiMe 3 ) 2
(6.16)
The reaction has also been extended to the analogous vinyl bromides [30].
Indeed, the alkenyl bromide 77 under normal reduction conditions gave the
bicyclic compound 78 in good yield by an SHi reaction given by the vinyl radical
(Reaction 6.17). Under these conditions, the reduction products could not be
observed which suggests a very fast unimolecular reaction.