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

176 Consecutive Radical Reactions
PhSe
X
O
73
CO 2Et
X = Ph
X = OPh
(TMS) 3 SiH,
80 atm CO
AIBN, 80 �C
O
O
X CO2Et 86%, trans:cis = 9:1
82%, trans:cis = 4:1
(7.81)
The field of alkyl radical macrocyclization reactions was further augmented
with an (n þ 1) strategy, which incorporates a CO unit in the macrocycle
[93]. Thus, in the presence of highly diluted (0.005–0.01 M) (TMS) 3SiH,
v-iodoacrylates underwent an efficient three-step radical chain reaction to
generate 10- to 17-membered macrocycles in 28–78 % yields, respectively (Reaction
7.82).
O I
n
O
(TMS) 3SiH,
30 atm CO
AIBN, 80 �C
n = 1,2,4,6,7,8 28-78%
O
O
O
n
(7.82)
Free-radical reaction of vinyl iodides having dienoate function in the presence
of (TMS) 3SiH and AIBN in refluxing benzene caused a tandem cyclization
reaction to produce (4 þ 1) and (4 þ 2) annulated compounds [94]. Reaction
(7.83) shows the transformation resulted from a tandem 5-exo, 6-endo cyclization
to give the isoindole skeleton where the stereogenic centres were highly
controlled, whereas Reaction (7.84) proceeded via a tandem 6-exo, 5-exo cyclization
to furnish a (4 þ 1) cycloadduct.
I
MeO2C I
MeO 2 C
N
Ts
N
Ts
Ph
Ph
(TMS) 3 SiH
AIBN, 80 �C
(TMS) 3SiH
AIBN, 80 �C
MeO 2C
H
MeO 2C
H
N
Ts
66%
N
Ts
Ph
H
Ph
H
70%, α:β = 3:2
(7.83)
(7.84)