Rhenium oxide carboxylic acid hydrogenation

Selective oxidation of N-1 of adenine derivatives is typically carried out with peracids <1998JOC3213>, but has also been achieved with hydrogen peroxide and catalytic methyltrioxorhenium (Scheme 10) <2000T10031>. The inclusion of pyridazine-2-carboxylic acid as a stabilizer for reactive rhenium peroxides led to increased yields. Caffeine did not react under these conditions. 

Rhenium catalysts. H. Smith Broadbent and co-workers have reported the preparation of a number of oxides of rhenium (RcbOt. ReOj, ReOa, ReO), which are effective hydrogenation catalysts, particularly for the reduction of carboxylic acids to primary alcohols. Kor the reduction of aromatic, olefinic. carbonyl, and nitro groups they are less aclivc than nickel or plutimim calalysts hence selective hydrogenation is possible. Bcn/ylic hydroxyl groups are stable to hydrogenolysis. 

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