Author(s)

Hisashi Masui, Masaru Takizawa, Yuki Sakai, Yasuhiro Kajiwara, Kiyofumi Wanibuchi, Mitsuru Shoji^*, Takashi Takahashi^*

Department of Pharmaceutical Sciences, Yokohama University of Pharmacy, Yokohama, Japan.

Desymmetrization reactions provide a powerful approach for the construction of complex molecules. Various methods have been developed for the selective monoprotection of symmetrical diols; however, their application to large-scale operations is limited. In this study, the monotetrahydropyranylation of symmetrical diols in a flow reactor has been developed, whereby the length of the flow reactor tube and the amount of acid were optimized. A higher selectivity for the monoprotected derivative was observed when the reaction was performed in a flow reactor compared with that observed in a conventional batch experiment. The efficient flow method developed herein can be applied to large-scale synthesis by numbering up the flow reactor without affecting the selectivity and yield. Since monoprotection can be achieved without using a large excess of diol, our developed flow method is effective when expensive diol must be used.

Desymmetrization, Selective Monoprotection, Flow Synthesis, Diols, Tetrahydropyranylation

Masui, H. , Takizawa, M. , Sakai, Y. , Kajiwara, Y. , Wanibuchi, K. , Shoji, M. and Takahashi, T. (2018) Selective Monoprotection of Symmetrical Diols in a Flow Reactor. International Journal of Organic Chemistry, 8, 264-271. doi: 10.4236/ijoc.2018.82019.