Table 1.

Different groups (-R₁ and -R₂) in Scheme 1.

Compd.	-R 1	-R 2
4a, 6a, 7a	-H	-H
4b, 6b, 7b	2-CH3	-H
4c, 6c, 7c	3-CH3	-H
4d, 6d, 7d	-H	4-CH3
4e, 6e, 7e	2-CH3	4-CH3
4f, 6f, 7f	2-CH3	5-CH3
4g, 6g, 7g	2-CH3	6-CH3
4h, 6h, 7h	3-CH3	4-CH3
4i, 6i, 7i	3-CH3	5-CH3
4j, 6j, 7j	2-CH2-CH3	-H
4k, 6k, 7k	-H	4-CH2-CH3
4l, 6l, 7l	-H	4-O-CH2-CH3