Table 3.
entry | R1 | R2 | R3 | 13 | yield, %a |
---|---|---|---|---|---|
1 | F3C | H | H | a | 90 |
2 | F | H | H | b | 97 |
3 | Me | H | H | c | 90 |
4 | H | F | H | d | 88 |
5 | H | MeO | H | e | 92 |
6 | H | Me | H | f | 88 |
7 | H | H | MeO | g | 85 |
8 | H | H | Et | h | n.r. |
9 | H | −HC=CH−CH=CH− | i | 83 | |
10 | j | 59 |
Isolated after silica gel chromatography.