A Clean, Simple, and Efficient Synthesis of 2-Substituted Aryl (Indolyl) Kojic Acid Derivatives by Kaolin/Ag Nanocomposite as a Reusable Catalyst: A Green Protocol

Table 5

Condensation of aromatic aldehyde, kojic acid, and indole derivatives in the presence of Kaolin/Ag nanocomposite catalyst.

Entry	Aldehyde	Indole	Product^a	Time; (min)	Yield (%)^b	M.p.; (°C) [Ref.]
1			4a	60	98	79–81 [18]
2			4b	65	83	96–98 [18]
3			4c	55	87	89-90 [18]
4			4d	60	92	86–88 [18]
5			4e	75	82	96–98 [18]
6			4f	70	90	96–98 [18]
7			4g	60	92	87–89
8			4h	65	90	Oil
9			4i	75	82	87–89
10			4j	90	85	169–171
11			4k	80	80	172–174
12			4l	87	82	167–169
13			4m	90	85	170–172

aAll the products were identified by 1H NMR and 13C NMR spectra and also by comparing of melting point and 1H NMR spectra with those of authentic samples reported in the literature.
bYields refer to isolated products.