Synthesis and structure-activity relationship (SAR) studies of 1,2,3-triazole, amide, and ester-based benzothiazole derivatives as potential molecular probes for tau protein.

The pyridinyl-butadienyl-benzothiazole (PBB3 15) scaffold was used to develop tau ligands with improved and properties for imaging applications to provide insights into the etiology and characteristics of Alzheimer's disease. The photoisomerisable -butadiene bridge of PBB3 was replaced with 1,2,3-triazole, amide, and ester moieties and fluorescence staining studies revealed that triazole derivatives showed good visualisation of Aβ plaques, but failed to detect the neurofibrillary tangles (NFTs) in human brain sections. However, NFTs could be observed using the amide 110 and ester 129.

An investigation of the allylation cascade reactions of substituted indigos.

In a continuation of the exploration of indigo cascade reactions, a series of -OMe, -Ph, -Br and -NO substituted indigos 1a-i were synthesised to probe electronic effects upon the outcome of allylation cascade reactions. When indigos 1a-i in the presence of base were reacted with allyl bromide, spiroindolinepyridoindolones 17-25 (36-75%) were obtained as the major products in each case, marking a shift in outcome relative to that previously reported for unsubstituted indigo. In electron-rich derivatives (-OMe, -Ph), -allylspiroindolinepyridoindolediones 26-29 (3-11%) were also isolated, which are most likely formed a Claisen rearrangement of the respective spiroindolinepyridoindolones 18-21.