An Efficient Synthesis of Bis-indolylindane-1,3-diones, Indan-1,3-diones, and Indene-1,3(2H)-denies Using [Hbim]BF₄ Ionic Medium

Table 2

Preparation of 5 in ionic liquid [Hbim]BF₄.

Entry	R^1	R^2	R^3	R^4	Product	Time (min)	Yield (%)^a	Melting Point
								Report, m.p. (°C)	Li. m.p. (°C) [Ref]
1	H	H	H	H	5aa	10	93	277–279	276–278 [9]
2	H	H	F	H	5ab	12	90	224–226	Prepared for the first time
3	H	H	Br	H	5ac	8	92	275–277	274–276 [9]
4	H	CH3	H	H	5ad	7	94	195–197	Prepared for the first time
5	CH3	H	H	H	5ae	5	95	183–185	182–184 [9]
6	H	H	H	CH3	5ba	7	93	217–219	218–220 [9]
7	H	H	F	CH3	5bb	7	92	210–212	Prepared for the first time
8	H	H	Br	CH3	5bc	7	95	219–221	Prepared for the first time
9	H	CH3	H	CH3	5bd	5	97	205–207	204–206 [9]
10	CH3	H	H	CH3	5be	3	95	171–173	170–172 [9]
11	H	H	H	Cl	5ca	10	94	228–230	Prepared for the first time
12	H	H	F	Cl	5cb	15	91	199–201	Prepared for the first time
13	H	H	Br	Cl	5cc	8	93	223–225	Prepared for the first time
14	H	CH3	H	Cl	5cd	7	94	253–255	Prepared for the first time
15	CH3	H	H	Cl	5ce	5	95	185–187	186–188 [9]

aYield refers to pure products after crystallization.