Original scientific paper

Hydropyrimidines. II. Observations on Selective Hydrogenation of Some Hydroxypyrimidines

V . Škarić ; Institute »Ruder Boskovic«, Zagreb, Croatia, Yugoslavia
B. Gašpert ; Institute »Ruder Boskovic«, Zagreb, Croatia, Yugoslavia
Đ. Škarić ; Institute »Ruder Boskovic«, Zagreb, Croatia, Yugoslavia

Abstract

Contrary to the generally accepted principle that selective
reduction of pyrimidines occurs art the ~5 • 6 position, the partial
hydrogenation of 2-hydroxypyrimidine (I) over Adams' catalyst in
ethanol was shown to afford 3,6-dihydro-2-hydroxypyrimidine (II).
Upon subsequent reduction 3,4,5,6-tetrahydro-2-hydroxypyrimidine
(III) was obtained.
In order to ascertain the structure of the dihydro compound
structurally unambiguous 1-methyl-2-oxopyrimidine (IV) was
subjected to the same partial hydrogenation. The NMR spectra of so
obtained dihydro-1-methyl-2-oxopyrimidine (V) and the corresponding
tetrahydro derivative VI, in particular the chemical
shifts of their methyl groups (n 7.08 and 7.06 resp.), complied
with the requirements for a 3,6-dihydro compound.
4-Hydroxypyrimidine (IX) did not react with hydrogen under
the above mentioned conditions. However, very slow reduction to
1,2,3,6-tetrahydro-4-hydroxypyrimidine . (X) occured with rhodium
on carbon as catalyst. On the other h and rhodium on carbon was
shown to be very active for reduction of 3-methyl-4-oxopyrimidine
(XII) yielding 1,2,3,6-tetrahydro-3-methyl-4-hydroxypyrimidine
(XIII). In this series the isolation of dihydro derivatives failed.

Keywords

Hrčak ID:

208313

URI

https://hrcak.srce.hr/208313

Publication date:

30.9.1964.

Visits: 567 *