Proficient Procedure for Preparation of Quinoline Derivatives Catalyzed by NbCl₅ in Glycerol as Green Solvent

Table 3

Synthesis of quinolones by the NbCl₅-catalyzed in glycerole^a.

Entry	Substrate 1	Substrate 2	Quinoline 3	Reaction time (min)	Yield (%)^b
1	1a	2a	3a	15	95
2	1b	2a	3b	20	98
3	1a	2b	3c	25	93
4	1b	2b	3d	35	95
5	1a	2c	3e	50	87
6	1b	2c	3f	60	78
7	1a	2d	3g	45	82
8	1b	2d	3h	50	85
9	1b	2e	3i	70	80
10	1a	2f	3j	60	78
11	1b	2f	3k	45	84
12	1a	2g	3l	75	81
13	1a	2h	3m	50	79
14	1b	2i	3n	40	85
15	1b	2j	3o	55	82
16	1b	2h	3p	45	89
17	1b	2k	3q	45	90
18	1b	2l	3r	90	84
19	1b	2m	3s	90	88
20	1a	2n	3t	90	86
21	1b	2o	3u	90	91
22	1a	2p	3v	90	79
23	1a	2s	3w	90	76

^aReaction conditions: carbonyl compounds (1.0 mmol), 2-amino-5-chlorobenzophenone or 2-amino benzophenone (1 mmol), NbCl₅ (0.1 mmol), and glycerol (2 mL); reactions conducted at 110°C.
^bThe yield refers to pure isolated product.