Table I.

Synthesis and Characterization^e of New Xanthine Derivatives (compound suffixes a, b, and c refer to R = Me, Et, and Pr, respectively)

no.	% yield	mp, °C	formula	anal.
2b	67a	>310	C17H18N4O5·H2O	C, H, N.
3a	61	294–296	C17H18N4O5·1/4H2O	C, H, N
3b	86	267–269	C19H22N4O5	C, H, N
4b	71	275–277	C20H24N4O5·1/2DMF	C, H, N
5b	88	300–302	C19H23N5O4·1/2H2O	C, H, N
6a	99	255–258	C17H20N6O4·1/4H2O	C, H, N
6b	92	233–235	C19H24N6O4·H2O·DMF	C; H, Nb
7b	58	>310	C24H26N5O4·4/5H2O	C, H, N
8a	60	>310	C24H23N5O6	H, N; Cc
8b	92	310–313	C26H27N6O6·1/2H2O	C, H, N
9a	94	280 dec	C25H27N7O5	H, N; Cd
9b	77	273–278d	C27H31N7O5·3/4H2O	C, H, N
10b	79	215–219	C38H50N8O9·1/2H2O	C, H, N
10c	95	207–211	C40H54N8O9	C, H, N
11b	100	270–275	C25H36N8O5·2HB·2H2O	C, H, N
11c	83	dec begin 190	C27H40N8O5·3HBr	C, H, N

^aYield calculated from 6-amino-1,3-diethyl-5-nitrosouracil, which was treated with Na₂S₂O₄ and then condensed with [(4-formylphenyl)oxy]acetic acid, and the benzylidene adduct was oxidized with NaIO₄ as in ref 12.

^bH calcd 6.77, found 6.25; N calcd 19.95, found 18.97.

^cC calcd 60.37, found 52.82.

^dC calcd 59.40, found 51.49.

^eProton NMR resonances (300 MHz) in ppm from Me₄Si for selected compounds in (CD₃)₂SO. 6b: δ 8.15 (t, 1 H, amide NH), 8.05 and 7.05 (each d, J = 8.7 Hz, 2 H, Ar), 4.54 (s, 2 H, CH₂O), 4.08 and 3.94 (each q, 2 H, Et methylene), 3.21 (m, 2 H, CH₂NHCO), 2.68 (t, J = 6.2 Hz, 2 H, CH₂NH₂), 1.26 and 1.13 (each t, 2 H, J = 6.8 Hz, CH₃). 8a: δ 8.10 (d, 2 H, Ar, meta to O), 7.58 (d, 2 H, Ar, ortho to NH), 7.23 (d, 2 H, Ar, ortho to CH₂), 7.13 (d, 2 H, Ar, ortho to O), 4.79 (s, 2 H, CH₂O), 3.63 (s, 2 H, CH₂Ar), 3.61 (s, 3 H, OCH₃), 3.49 and 3.27 (each s, 3 H, NCH₃). 9a: δ 8.06 (d, 2 H, Ar, meta to O), 8.02 (1 H, amide NH), 7.56 (d, 2 H, Ar, ortho to NH), 7.21 (d, 2 H, Ar, ortho to CH₂), 7.13 (d, 2 H, Ar, ortho to O), 4.75 (s, 2 H, CH₂O), 3.48 and 3.24 (each s, 3 H, NCH₃), 3.36 (s, 2 H, CH₂Ar), 3.07 (m, 2 H, CH₂NHCO), 2.60 (t, J = 6.7 Hz, 2 H, CH₂NH₂).