ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Synthesis of new 5-bromo derivatives of indole and spiroindole phytoalexins

Lucia Očenášová, Peter Kutschy, Jozef Gonda, Martina Pilátová, Gabriela Gönciová, Ján Mojžiš, and Pavel Pazdera

^aDepartment of Organic Chemistry, Institute of Chemical Science, Faculty of Science, P. J. Šafárik University, Moyzesova 11, 040 01 Košice, Slovakia

E-mail: lucia.ocenas@gmail.com

Abstract: Electrophilic aromatic substitution is one of the most thoroughly studied reactions in organic chemistry. In the present paper, the 5-brominated spirobrassinol methyl ethers VII, VIII were obtained by electrophilic substitution of the aromatic core of indoline at the C-5 position in the presence of various brominating agents. The same products were also prepared from 5-bromoindole (IX) following the sequence for the synthesis 1-methoxyspirobrassinol methyl ether (V) from indoline. In addition, the new related 5-bromospiroindoline derivatives XX–XXIII were synthesised and their biological activity on human tumour cell lines was examined. The presence of bromine in the indole or indoline skeleton at the C-5 position resulted in the partial increase in anticancer activity on leukaemia cell lines (Jurkat, CEM). The structures of the newly prepared products were determined by ¹H and ¹³C NMR spectroscopy, including HSQC, HMBC, COSY, NOESY and DEPT measurements.

Keywords: 5-bromobrassinin – spiroindole phytoalexins – bromination – spirocyclisation – anti-proliferative activity

Full paper is available at www.springerlink.com.

DOI: 10.1515/chempap-2015-0230

Chemical Papers 70 (5) 635–648 (2016)