We report a refined and expanded synthetic study of 4,4-difluoro-1,3,5,7-tetramethyl-8-(aryl)-4-bora-3a,4a-diaza-s-indacene under treatment with POCl3/DMSO. The 2-chloro-6-methylsulfide derivative (Kim TI, Park S, Choi Y and Kim Y. Chem. Asian J. 2011; 6: 1358-61.) was one of five co-eluants, including 2,6-disulfido and -dichloro species, and mono-substituted counterparts. The 8-meso tail group modifies product distribution. The different sulfur-containing products undergo different "off-on" responses with NaOCl (10 equiv.). Compounds 4b and 2b exhibit low toxicity and were found to enter juxtanuclear regions in neuroblastoma.
Thiocyanation and formation of thioalkylated BODIPYs is a simple and reliable way for their chemical modification and photophysical tuning.