Platinum benzyl amines

The ease of hydrogenolysis of benzyl amines depends on the nature of the substituents on the nitrogen atom. The debenzylation of tertiary benzyl amines takes place over palladium on charcoal at 25°-50°C and 2-4 atmospheres of hydrogen (Eqn. 20.43). 2 Platinum and rhodium catalysts generally promote... 

Aliphatic and Benzyl Amines[16] Primary amines are easily oxidized at platinum electrodes, the first step being as follows ... 

Nitro Compounds. Under mild conditions, aromatic nitro compounds are hydrogenated easily to amines.518 The reaction may give partially reduced products, according to the circumstances. Palladium, platinum, and nickel are used frequently for this reaction. For example, nitro and benzyl ester functions are reduced on Pd(OH)2/C on THF and on Pd/C in EtOH.519 Aliphatic nitro groups are reduced more slowly. 

Labetalol Labetalol, 2-hydroxy-5-[l-hydroxy-2-[(l-methyl-3-phenylpropanol)amino)] ethyl] benzamide (12.1.12) is synthesized by the WaUcylation of iV-benzyl-Af(4-phenyl-2-butyl)amine 5-bromacetylsalicylamide and forming aminoketone (12.1.11), which is further debenzylated by hydrogen using a palladium-platinum on carbon catalyst into labetalol (12.1.12) [28-30]. 

In general, the breaking of the carbon—oxygen bond appears difficult to achieve and needs activation by strongly polar groups. For these reasons, alcohol deprotection is carried out cathodically under the form of benzylic[91] and allylic [92] ethers as well as tosylates [91]. Thus, Torii [93] used the 4-nitrobenzyl group to protect alcohols. The deprotection was carried out in two steps (1) reduction of the nitrogroup of the amine and (2) oxidation of the amine at a platinum electrode (yield up to 93%). 

Hydrogenolysis (reduction with bond breaking) of benzylamines resulting in the formation of toluene and debenzylated amine is formally a reduction of the amine. Thus, as shown in Equation 10.39, treatment of A -benzyl-1,23,4-tetrahydroisoquinoline dissolved in ethanol with hydrogen (H2) gas at about 1 atm pressure in the presence of aqueous hydrochloric acid (HCl(aq)) and a platinum (Pt) catalyst, results in formation of the tetrahydroisoquinoUne base (present as is hydrochloric acid salt) and toluene. 

---