Page 459 - Advanced Organic Chemistry Part B - Reactions & Synthesis

432 Scheme 5.8. Dehalogenation with Stannanes

CHAPTER 5 1 a Bu SnH
3
Br H
Reduction of
Carbon-Carbon Multiple
Bonds, Carbonyl 2 b CF 3 CF 3
Groups, and Other Ph SnH
3
Functional Groups Br H
99%
3 c O O
Bu SnH
3
Cl H
Cl Cl 84%
4 d Cl Bu SnH
3
F F
5 e O O
O O
(CH ) SnCl
3 3
I CH OCH 3 NaBH 4 CH OCH 3
2
2
hν
O CCH 3 O CCH 3
2
2
6 f Br D
1) Bu SnD
3
Br 2) KF, H O D
Br 2 D 92%
Br D
a. H. G. Kuivila, L. W. Menapace, and C. R. Warner, J. Am. Chem. Soc.,
84, 3584 (1962).
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c. W. T. Brady and E. F. Hoff, Jr., J. Org. Chem., 35, 3733 (1970).
d. T. Ando, F. Namigata, H. Yamanaka, and W. Funasaka, J. Am. Chem.
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out under illumination to provide for chain initiation, and the reactant was prepared
by an iodolactonization reaction. The sequence iodolactonization-dehalogenation is
frequently used in the synthesis of five-membered lactones. Entry 6 illustrates the
use of dehalogenation with deuterium incorporation. The addition of the fluoride salt
facilitates workup by precipitation of tin by-products.
Hypophosphorous acid has been used as a hydrogen atom donor in the dehalo-
genation of nucleosides. 202

O O
N NH N NH
H PO 2
3
CO radical initiator
CH 3 2 O N N CH CO 2 O N N
3
Br DME
2
O 2 CCH 3 O CCH 3
202
S. Takamatsu, S. Katayama, N. Hirose, M. Naito, and K. Izawa, Tetrahedron Lett., 42, 7605 (2001).