Molecular structures enumeration and virtual screening in the chemical space with RetroPath2.0

Table 1 Number of generated alkane isomers by canonical augmentation algorithm and isomer transformation algorithm

No. of carbon atoms	No. of structures output by canonical augmentation algorithm	No. of structures output by isomer transformation algorithm	No. of iterations for isomer transformation algorithm
1	1	1	1
2	2	1	1
3	3	1	1
4	5	2	2
5	8	3	3
6	13	5	3
7	22	9	4
8	40	18	5
9	75	35	5
10	150	75	6
11	309	159	7
12	664	355	7
13	1466	802	8
14	3324	1858	9
15	7671	4347	9
16	18,030	10,359	10
17	42,924	24,894	10
18	103,447	60,523	10

The numbers agree with earlier calculations [30]. For a given number of carbon atoms (N), the canonical augmentation generates all alkanes from 1 to N carbon atoms, while the isomer transformation enumeration generates alkanes having only N carbon atoms, one can thus verify that at any given number of carbon atoms N, the numbers of structures generated by the canonical augmentation algorithm equals the sum of numbers of isomers generated by the transformation algorithm up to N

ISSN: 1758-2946