Table 1.

Synthesis of the target 3-nitro-2H-chromenes 5.

“Synthesis Route”
Aldehyde	R1	R2	Nitrostyrene	R3	Chromene	Yield
3a	H	H	4a	H	5a	60
3b	OMe	H	4a	H	5b	67
3c	Me	H	4a	H	5c	63
3d	F	H	4a	H	5d	50
3e	Cl	H	4a	H	5e	40
3f	Br	H	4a	H	5f	50
3g	OCF3	H	4a	H	5g	59
3h	NO2	H	4a	H	-	-
3i	H	OMe	4a	H	5h	65
3j	H	Me	4a	H	5i	52
3k	H	OEt	4a	H	5j	66
3l	tBu	tBu	4a	H	-	-
3a	H	H	4b	OMe	5k	71
3a	H	H	4c	Me	5l	40
3a	H	H	4d	F	5m	82
3a	H	H	4e	Cl	5n	86
3a	H	H	4f	Br	5o	95
3f	Br	H	4f	Br	5p	71
3e	Cl	H	4f	Br	5q	70
3m	Br	Br	4f	Br	5r	44
3n	Br	Cl	4f	Br	5s	51
3o	Cl	Cl	4f	Br	5t	47