Copper- and Ligand-Free Sonogashira Cross-Coupling: Access to Novel 3-Aminoindole Derivatives and Their Biological Evaluations

Table 1

Copper- and ligand-free Sonogashira type reaction to produce indole 8 from 2-iodoaniline 5.

Entry	Solvent	Pd (II) cat.	Acid	Salt	Time (h)	T (°C)	Yield (%)
							7	8
1	DMSO	PdCl2	HCl	TBAF	24	80	15	0
2	DMSO	Pd (OF3Ac)2	AcOH	TBAF	24	80	0	0
3	DMSO	Pd (OAc)2	AcOH	TBAF	24	80	12	21
4	DMSO	Pd (OAc)2	AcOH	TBAF (2 eq.)	24	80	13	28
5	DMSO	Pd (OAc)2	AcOH	TBAF (3 eq.)	24	80	21	50
6	DMSO	Pd (OAc)2	AcOH	TBAF (4 eq.)	24	80	18	60
7	DMSO	Pd (OAc)2	AcOH	TBAF (5 eq.)	24	80	10	70
8	DMSO	Pd (OAc)2	AcOH	TBAF (6 eq.)	24	80	3.4	89
9	DMSO	Pd (OAc)2	AcOH	Cs2CO3 (6 eq.)	24	80	73	22
10	DMSO	Pd (OAc)2	AcOH	K2CO3 (6 eq.)	24	80	55	41
11	DMSO	Pd (OAc)2	AcOH	Na2CO3 (6 eq.)	24	80	0	96
12	DMSO	Pd (OAc)2	AcOH	Et3N (6 eq.)	24	80	6	86