An Efficient and Practical Method for the Synthesis of Saxagliptin Intermediate 2-(3-Hydroxy-1-adamantane)-2-oxoacetic Acid and Its Optimization

Table 2

The results of central composite design-response surface methodology.

Number	X a (mol/mol)	X b (h)	X c (°C)	X d (g)	Actual yield (%)
1	0	0	0	2	53.3
2	2	0	0	0	56.9
3	0	−2	0	0	58.9
4	0	0	2	0	50.5
5	1	−1	1	1	63.22
6	−1	−1	1	1	60.7
7	0	0	0	−2	50.3
8	0	0	0	0	72.6
9	−1	1	−1	1	60.3
10	−1	−1	1	−1	55
11	−1	−1	−1	−1	56.44
12	1	−1	−1	−1	55.5
13	1	1	1	−1	62.7
14	−2	0	0	0	49.5
15	1	1	−1	1	59.9
16	0	0	−2	0	46.1
17	−1	−1	−1	1	60.5
18	0	0	0	0	73.45
19	1	1	1	1	61.22
20	0	2	0	0	53.5
21	1	1	−1	−1	57.9
22	0	0	0	0	74.7
23	−1	1	1	−1	60.2
24	0	0	0	0	75.8
25	0	0	0	0	73.9
26	0	0	0	0	69.9
27	1	−1	1	−1	59.7
28	1	−1	1	1	56.9
29	−1	1	1	1	54.9
30	1	−1	−1	1	61.2