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

158 Consecutive Radical Reactions
O
O
28
O
SePh
CO2Me (TMS) 3SiH
Et 3B, O 2, r.t.
H
O
O
H
O
91%, ds>95:5
CO 2Me
(7.34)
The use of PhSeSiR3 coupled with a photoinduced electron transfer methodology
has been used for the C w C bond formation via the group transfer
radical reactions. Two examples are given in Reaction (7.35) starting either
from a bromide or phenylselenide, which afford the same furanic compound
[45,46]. The reaction mechanism of a certain complexity has been understood in
some detail. Scheme 7.5 shows the mechanistic paths, concerning the construction
of C w C bond (for the mechanistic paths of PhSeSiR3 : formation see
Section 1.1). In particular, silyl radicals generated from the mesolysis of
PhSeSiR3 : abstract Br or PhSe groups to generate alkyl radicals, while oxidative
dimerization of the counteranion PhSe to PhSeSePh functions as the
radical terminator of the cyclized radical.
O
X
PhSe
DMA, AH2 + t-BuPh2SiSePh (7.35)
CH
OEt
3CN, hν
O
OEt
X = Br
X = SePh
PhSe
DMA = 9,10-dimethoxyanthracene
AH 2 = ascorbic acid
O 2
PhSeSePh
PhSe
PhSeSiR 3
mesolysis
R 3 Si
81%, cis:trans = 16:84
75%
X
R 3 SiX
Scheme 7.5 Group transfer radical reation using a photoinduced electron transfer method
for the generation of PhSeSiR 3 : (see Scheme 1.1 in Chapter 1)