Page 1050 - Advanced Organic Chemistry Part A - Structure and Mechanisms, 5th ed (2007) - Carey _ Sundberg

1034 styrene. The -bromoaldehyde additive was shown to increase the regioselectivity.
A similar effect has been noted for PBr , 173 but the mechanistic basis is not estab-
3
CHAPTER 11 lished in either case. The reaction in Entry 3 was carried out under irradiation from
Free Radical Reactions

Scheme 11.5. Free Radical Additions to Alkenes
A. Addition of Hydrogen Bromide
1 a CH 3 CH C(CH ) HBr CH CHCH(CH )
3 2
3 2
3
(PhCO )
2 2
Br 55%
2 b PhCH CH 2 HBr PhCH CH Br
2
2
(CH ) CCH O
3 2
Br
3 c CH 2 CHCH C(CH ) CCH 3 HBr BrCH CH CH C(CH ) CCH 3
2
3 2
3 2
2
2
2
hv
O O 76%
B. Additions of Tetrahalomethanes
(PhCO )
2 2
4 d CCl 4 + H C CH(CH ) CH 3 Cl CCH CH(CH ) CH 3
2 5
3
2
2
2 5
90 –105°C
Cl 75%
5 e BrCCl 3 + H C C(C H ) hv Cl 3 CCH C(C H )
2 5 2
2
2
2 5 2
Br 91%
(PhCO ) CCl 3 CCl 3
2 2
6 f CCl 4 + + Cl
73% Cl 4%
Cl
(PhCO )
7 g CCl 4 + H C CHC(CH ) 2 2 Cl CCH CHCH(CH )
2
3 2
3
2
3 2
80°C
OH OH 70%
Fe
8 h BrCl 3 + PhCH 2 CH CH 2 PhCH CHCH CCl 3
2
2
Br 96%
C. Addition of other Carbon Radicals
hv
2 7
9 i CH CH O + H C CH(CH ) CH 3 CH C(CH ) CH 3
2 5
3
2
3
O 64%
j
10 CH CH O + C CCO C(CH ) hv CH CCH CH CO C(CH )
3 H 2 2 3 3 3 2 2 2 3 3
O 99%
O
(PhCO )
2 2
k
11 CH (CH ) CH O + H C CHCO CH CH (CH ) C(CH ) CO CH
3 2 2 2 2 3 3 2 2 2 2 2 3
N-hydroxy-
phthalimide 80%
O
t BuON NOt Bu
l
12 CH (CH ) CH O + H C CCH 3 CH CH CH CCH CHCH 3
3
2 2
2
2
2
2
3
CO CH
HSCH 2 2 3
O CCH 3 O CCH 3
2
2
80%
(Continued)
173
G. A. Olah and T. R. Hockswender, Jr., J. Org. Chem., 39, 3478 (1974).