Adam’s catalyst

Cyclopropane rings are opened hydrogenolytically, e.g., over platinum on platinum dioxide (Adam s catalyst) in acetic acid at 2 - 4 bars hydrogen pressure. The bond, which is best accessible to the catalyst and most activated by conjugated substituents, is cleaved selectively (W.J. Irwin, 1968 R.L. Augustine, 1976). Synthetically this reaction is useful as a means to hydromethylate C—C double bonds via carbenoid addition (see p. 74f. Z. Majerski, 1968 C.W. Woodworth, 1968). 

Nitro groups in the homocyclic ring of 1,2-benzisoxazoles have been reduced to the corresponding amino groups without opening of the isoxazole nucleus. SnCU/HCl and Adam s catalyst/H2 have both proved effective in this respect. Similar behavior was observed for nitro groups in the isomeric 2,1-benzisoxazoles (67AHC(8)277,pp.295,33l). 

A novel synthesis of 2-aminoquinoxalin-3-one 1-oxide has been effected by the hydrogenation of o-nitro-l-cyanoformanilide in ethanol in the presence of Adam s catalyst.- ... 

Thus, all five triple bonds in decamethyl[5]pericycline 3 can be completely hydrogenated to yield the corresponding saturated cyclic hydrocarbon 78 under platinum catalysis (Pt02, Adam s catalyst), albeit with some difficulty (Fig. 6). 

Acyloin condensation of diester 30a with sodium in liquid ammonia, followed by direct hydrogenation in the presence of Adam s catalyst, furnished the diol 32 in 49% yield. Diol 32 was transformed into the cyclic thiocarbonyl derivative (80% yield) which after heating with trimethylphosphite [14] afforded twistene 33 in 50% yield. Hydrogenation of 33 gave a compound identical in all respects with twistane 1. From the diester (-)-30a (+)-twistene was obtained, m.p. 35.5-36.5 °C, +... 

Cyclopentadiene adducts (mono-, tetra- and hexa-adducts) of were stabilized against retro-reaction by selective hydrogenation and bromination of the pendant groups [21]. Utilization of Adam s catalyst and dilute bromine solutions exclusively leads to an addition to the cyclopentene double bonds, because itself is inert towards these reagents. The increased stability of the reduced cycloadducts can be demonstrated by mass spectrometry [21]. 

Addition of hydrogen atoms in the presence of a metal catalyst to double or triple bonds is known as hydrogenation or catalytic hydrogenation. Alkenes and alkynes are reduced to alkanes by the treatment with H2 over a finely divided metal catalyst such as platinum (Pt—C), palladium (Pd—C) or Raney nickel (Ni). The platinum catalyst is also frequently used in the form of Pt02, which is known as Adams s catalyst. The catalytic hydrogenation reaction is a reduction reaction. 

In step b, Mander s reagent was used to recover (R)-47 after treatment of the intermediate with LDA, followed by methyl chloroformate. Reduction of the acetylene functionality to (R)-48 was proceeded with Adam s catalyst in MeOH under hydrogen. Final cyclization could not be achieved with NaH, although more vigorous reaction conditions using -BuLi gave (R)-50 in moderate yield. 

Jacobs has used Adam s catalyst with a lipase enzyme to effect the DKR of a variety of amines in high yield and optical purity (Table 13.1 [16]). The nature of the Pd catalysts may prevent wide application, as they are nonspecific and can affect other groups in the substrate. 

The original conditions, called the Gattermann Reaction / Formylation, were to add HCN, HC1 and ZnCh (known as Adam s Catalyst) directly. Use of Adam s catalyst avoids using gaseous HCN. 

Brown-black, insoluble, anhydrous, platinum(IV) oxide is made by fusing hexachloroplatinic(IV) add with NaN03 at about 500VC. The alkali salts are washed out with H20 to free the fine insoluble residue of platinum(IV) oxide. This compound is known as Adam s catalyst. 

Reduction of the pyridine ring as well as the 9,10-double bond was achieved using Adams s catalyst in the presence of 1 equiv. of 0.1 M HCI in methanol. The resulting mixture of diastereomers (404) was then saponified to afford (405) as a mixture of four diastereomers. 

DeoxyanthracyclinesHydrogenation of anthracyclines la or lb catalyzed by Pd/BaSQ, gives 7-deoxy-l (97% yield), which on further hydrogenation is converted into a 5,7-bisdeoxy product. However, hydrogenation of 1 catalyzed by Adam s catalyst in methanol containing chloroacetic acid affords the 5-deoxy product 2 in about 70% yield. 

Adams s catalyst is formally Pt02, and you have already seen this at work in one or two examples. The actual catalyst is, however, not the oxide of platinum, but the platinum metal that forms by reduction of Pt02 to Pt during the hydrogenation... 

---