Table 1.
compd | R1 | R2 | R4 | mp1 (°C) (lit. mp) | yield1 (%) |
---|---|---|---|---|---|
11a | CH3 | H | CH3 | 290–295 | a |
11b | H | H | benzyl | >250 (>300)34 | 90 |
11c | CH3 | H | H | >270 (>330)16 | 75 |
11d | H | phenyl | CH3 | >250 (>360)35 | 46 |
11e | CH3 | phenyl | H | >250 | 80 |
11f | CH3 | phenyl | CH3 | >250 (300)36 | 85 |
11g | H | styryl | CH3 | >270 | 80 |
11h | CH3 | styryl | CH3 | >270 | 88 |
Theobromine (11a) was commercially available.