C-2-13
Toward Crowdsourcing Evaluation ofSynthetic Accessibility
1

Yukino Baba 	  	 yukino_baba@mist.i.u-tokyo.ac.jp
Hisashi Kashima 1

kashima@mist.i.u-tokyo.ac.jp

12
3

Tetsu Isomura 2

isomura.tetsu@mx.kaiteki-institute.com

Hirofumi Nakano 3

h-nakano@mol.f.u-tokyo.ac.jp

Department of Mathematical Informatics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku,
Tokyo 113-8656, JapanThe KAITEKI Institute, Inc., 1-1-1 Marunouchi, Chiyoda-ku, Tokyo 100-8251, Japan
Open Innovation Center for Drug Discovery, The University of Tokyo, 7-3-1 Hongo,Bunkyo-ku, Tokyo 113-0033, Japan

Keywords: Synthetic accessibility, Crowdsourcing, Human computation
A rapid method for the assessment of synthetic accessibility for a vast number of chemicalcompounds is expected to bring about a breakthrough in the drug discovery. Although several
computational methods have been proposed for estimating the synthetic accessibility [1-3], they do
not meet the requirements of both quick computation time and high estimation accuracy. In thefield of computer science, crowdsourcing has received considerable attention for being an efficientand scalable approach for solving complicated tasks that are difficult for computers but relatively
easier for humans. Using crowdsourcing platforms such as Amazon Mechanical Turk [5], one caneasily outsource various professional and non-professional tasks to a large group of people online.
Jobs on crowdsourcing are typically decomposed into small and simple tasks that can be solved inparallel by different workers.
As the first step toward creating a crowdsourcing platform where the synthetic accessibility of anumber of compounds is assessed by people with different levels of expertise and backgrounds, weinvestigate the consistency among experienced medicinal chemists in assessing syntheticaccessibility. Unlike previous studies [2, 4], we prepared the following three compound groups:
Already existing compounds, ones having substructures that are hard to be synthesized, and ones
having novel substructures. We picked ten compounds from each group and asked the experienced
medicinal chemists to rate the synthetic accessibility of each compound on a five-point scale
within several minutes. Results show that there is a high correlation between the assessments given
by a subset of the chemists.
[1] Baber, J. C., Feher, M.: Predicting Synthetic Accessibility: Application in Drug Discovery andDevelopment. Mini Reviews in Medicinal Chemistry, 4:681-692, 2004.
[2] Boda, K., Seidel, T., Gasteiger, J.: Structure and Reaction based Evaluation of SyntheticAccessibility. Journal of Computer-Aided Molecular Design, 21:311-325, 2007.
[3] Ertl, P., Schuffenhauer, A.: Estimation of synthetic accessibility score of drug-like molecules
based on molecular complexity and fragment contributions, Journal of Cheminformatics, 1:8,2009.
[4] Takaoka, Y., Endo, Y., Yamanobe, S., Kakinuma, H., Okubo, T., Shimazaki, Y., Ota, T.,
Sumiya, S., Yoshikawa, K.: Development of a Method for Evaluating Drug-Likeness and Ease ofSynthesis Using a Data Set in Which Compounds Are Assigned Scores Based on Chemists'
Intuition. Journal of chemical information and computer sciences, 43:1269-1275, 2003.
[5] http://mturk.com