Page 418 - Advanced Organic Chemistry Part B - Reactions & Synthesis

Table 5.2. Conditions for Catalytic Reduction of Various Functional Groups a 391
Reactant Product Catalyst Conditions SECTION 5.2
Catalytic Hydrogenation
of Carbonyl and Other
C C C C Pd, Pt, Ni, Rapid at room temperature (R.T.) and 1 atm Functional Groups
Ru, Rh except for highly substituted or hindered cases
H H
C C C C Lindlar R. T. and low pressure, quinoline or lead added to
deactivate catalyst
H H
Rh, Pt Moderate pressure (5–10 atm), 50–100°C

Ni, Pd High pressure (100–200 atm), 100–200°C
O RCHR
Pt, Ru Moderate rate at R. T. and 1–4 atm. acid-catalyzed
RCR OH
O RCHR Cu–Cr, Ni High pressure, 50–100°C
RCR OH
O
CR
R. T., 1–4 atm. acid-catalyzed
or CH R Pd
OR 2
CHR
NR 2
50–100°C, 1–4 atm
CHR CH 2 R Pd, Ni
O O
Pd R. T., 1 atm. quinoline or other catalyst
RCCI RCH moderator used
O
RCOH RCH 2 OH Pd, Ni, Ru Very strenuous conditions required
O
RCH OH Cu–Cr, Ni 200°C, high pressure
RCOR 2
RC N RCH NH 2 Ni, Rh 50–100°C, usually high pressure, NH 3 added to
2
O increase yield of primary amine
RCNH 2 RCH NH 2 Cu–Cr Very strenuous conditions required
2
RNO 2 RNH 2 Pd, Ni, Pt R. T., 1–4 atm
NR
CHNHR Pd, Pt R. T., 4–100 atm
RCR R 2
R Cl
R Br R H Pd Order of reactivity: I > Br > Cl > F, bases
R I promote reactions for R = alkyl
O H OH
C C C C Pt, Pd Proceeds slowly at R. T., 1–4 atm, acid-catalyzed

a. General References: M. Freifelder, Catalytic Hydrogenation in Organic Synthesis: Procedures and Commentary, John
Wiley & Sons, New York, 1978; P. N. Rylander, Hydrogenation Methods, Academic Press, Orlando FL, 1985.

Many enantioselective catalysts have been developed for reduction of functional
groups, particularly ketones. BINAP complexes of Ru II Cl or Ru II Br give good
2 2
enantioselectivity in reduction of -ketoesters. 49 This catalyst system has been shown
to be subject to acid catalysis. 50 Thus in the presence of 0.1 mol % HCl, reduction
proceeds smoothly at 40 psi of H at 40 C.

2
49 R. Noyori, T. Ohkuma, M. Kitamura, H. Takaya, N. Sayo, H. Kumobayashi, and S. Akutagawa, J. Am.
Chem. Soc., 109, 5856 (1987).
50
S. A. King, A. S. Thompson, A. O. King, and T. R. Verhoeven, J. Org. Chem., 57, 6689 (1992).