Practical synthetic strategies towards lipophilic 6-iodotetrahydroquinolines and -dihydroquinolines.
The synthesis of novel tetrahydroquinolines (THQ) and dihydroquinolines (DHQ) are reported using three practical, scalable synthetic approaches to access highly lipophilic analogues bearing a 6-iodo substituent, each with a different means of cyclisation. A versatile and stable quinolin-2-one intermediate was identified, which could be reduced to the corresponding THQ with borane reagents, or to the DHQ with diisobutylaluminium hydride via a novel elimination that is more favourable at higher temperatures. Coupling these strongly electron-donating scaffolds to electron-accepting moieties caused the resulting structures to exhibit strong fluorescence.
Centre for Sustainable Chemical Processes, Department of Chemistry, Durham University, South Road, Durham, DH1 3LE, UK.
David R
DR
Chisholm
Centre for Sustainable Chemical Processes, Department of Chemistry, Durham University, South Road, Durham, DH1 3LE, UK.
Garr-Layy
GL
Zhou
Centre for Sustainable Chemical Processes, Department of Chemistry, Durham University, South Road, Durham, DH1 3LE, UK; Biophysical Sciences Institute, Durham University, South Road, Durham, DH1 3LE, UK.
Ehmke
E
Pohl
High Force Research Limited, Bowburn North Industrial Estate, Bowburn, Durham, DH6 5PF, UK.
Roy
R
Valentine
Centre for Sustainable Chemical Processes, Department of Chemistry, Durham University, South Road, Durham, DH1 3LE, UK.
Andrew
A
Whiting
cyclisation; dihydroquinoline; elimination; reduction; tetrahydroquinoline