Page 398 - Advanced Organic Chemistry Part B - Reactions & Synthesis

Scheme 5.1. Stereochemistry of Hydrogenation of Some Alkenes 371
A. Examples of preferential syn addition from less hindered side SECTION 5.1
1 a CH 3 CH 3 CH 3 Addition of Hydrogen at
H Pt H CH H Carbon-Carbon Multiple
Bonds
CH 2 3 + H
H 2 H CH 3
70% 30%
2 b CH 3 Pt CH 3 CH 3

+
H 2 CH
CH 3 3 CH 3
70 – 85% 15–30%
3 a
CH 3 Pt CH 3 CH 3
+
CH 3 H 2 CH 3 CH 3
70% 30%
4 c H
CH 3
H
CH 3 H C CH 3
3
5 b CH 2 CH 3
–
Pt(BH ) C H
4
H 2
B. Exceptions 95%
6 d Pt, H 2
acetic H +
acid H
CH 3 CH 3 CH 3
80% 20%
7 e
2
2
2
2
CH 2 CH CO CH 3 CH CH CO CH 3
2
Pt
H 2
H CO CH
H CO CH 3 2 3
2
8 f H
Ni, H 2
H +
OH OH OH
95% 5%
a. S. Siegel and G. V. Smith, J. Am. Chem. Soc., 82, 6082, 6087 (1960).
b. C. A. Brown, J. Am. Chem. Soc., 91, 5901 (1969).
c. K. Alder and W. Roth, Chem. Ber., 87, 161 (1954).
d. S. Siegel and J. R. Cozort, J. Org. Chem., 40, 3594 (1975).
e. J. P. Ferris and N. C. Miller, J. Am. Chem. Soc., 88, 3522 (1966).
f. S. Mitsui, Y. Senda, and H. Saito, Bull. Chem. Soc. Jpn., 39, 694 (1966).