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

168 Consecutive Radical Reactions
radical species with expulsion of a methoxymethyl radical and generation of the
carbonyl group (Reaction 7.60) [70].
O
O
O
O
N
Br
O
(TMS) 3SiH AIBN, 140 �C
58 41% (7.2:1) 22%
O
O
N
O
+
O
O
N
O
(7.60)
Reaction (7.61) shows an example of macrocyclization which represents the
key step in the total synthesis of the macrolide ( )-zearalenone [71].
MeO
MeO O
O
Br
O
(TMS) 3 SiH O
AIBN, 85 �C
MeO
MeO O
55%
7.4 FORMATION OF CARBON–HETEROATOM BONDS
O
(7.61)
Alkyl, vinyl and aryl radicals can give homolytic substitution at a heteroatom
either inter- or intramolecularly thus forming C–heteroatom bonds.
A new entry for the synthesis of vinyl- and arylphosphonates has been
achieved by reaction of vinyl or aryl halides with trialkyl phosphites in the
presence of (TMS) 3SiH under standard radical conditions [72]. An example of
this intermolecular C w P bond formation is given in Reaction (7.62). Interestingly,
the reaction works well either under UV irradiation at room temperature
or in refluxing toluene.
Br
OMe
+
P(OMe) 3
(TMS) 3 SiH
AIBN, 110 �C
or
AIBN, hν, r.t.
O
P(OMe) 2
OMe
90-93%
(7.62)
Reaction (7.63) shows an example of C w S bond formation [73,74]. In
fact, the aryl radical formed by iodine abstraction by (TMS) 3Si: radical rearranged
by substitution to the sulfur atom, with expulsion of the acyl radical
and concomitant formation of dihydrobenzothiophene (60). This procedure