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The synthesis, X-ray structure, aromaticity and chemistry of 9-germafluorenyl dianion are reported. The X-ray structure of 9-germafluorenyl dianion shows C-C bond length equalization in the five-membered ring and C-C bond length alteration in benzenoid rings, indicating aromatic delocalization of electrons into the five-membered germole ring of 9-germafluorenyl dianion.

Our lab has developed a new series of self‐immolative MR agents for the rapid detection of enzyme activity in mouse models expressing β‐galactosidase (β‐gal). We investigated two molecular architectures to create agents that detect β‐gal activity by modulating the coordination of water to GdIII. The first is an intermolecular approach, wherein we designed several structural isomers to maximize coordination of endogenous carbonate ions. The second involves an intramolecular mechanism for q modulation. We incorporated a pendant coordinating carboxylate ligand with a 2, 4, 6, or 8 carbon linker to saturate ligand coordination to the GdIII ion. This renders the agent ineffective. We show that one agent in particular (6‐C pendant carboxylate) is an extremely effective MR reporter for the detection of enzyme activity in a mouse model expressing β‐gal. [ABSTRACT FROM AUTHOR]

The chemistry, structure of 1-silafluorenyl dianion, its derivatives are studied. Synthesis of 1-silafluorene dianion was done by potassium reduction of 1,1-dichloro-1-silafluorene in refluxing THF, the structure of which showed C-C bond length equalization in the five membered silole rings and C-C bond length alternation in the six-membered benzene rings.

Our lab has developed a new series of self-immolative MR agents for the rapid detection of enzyme activity in mouse models expressing β-galactosidase (β-gal). We investigated two molecular architectures to create agents that detect β-gal activity by modulating the coordination of water to Gd III . The first is an intermolecular approach, wherein we designed several structural isomers to maximize coordination of endogenous carbonate ions. The second involves an intramolecular mechanism for q modulation. We incorporated a pendant coordinating carboxylate ligand with a 2, 4, 6, or 8 carbon linker to saturate ligand coordination to the Gd III ion. This renders the agent ineffective. We show that one agent in particular (6-C pendant carboxylate) is an extremely effective MR reporter for the detection of enzyme activity in a mouse model expressing β-gal., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

[reaction: see text] A highly efficient stereoselective synthesis of unusual alpha-silylamines via a direct silyl anion addition reaction is reported. This approach is convergent and avoids any problematic aza-Brook shifts of the anionic intermediates. The use of enantiopure tert-butanesulfinyl imines as the electrophiles affords exceedingly high levels of diastereocontrol for the newly formed stereogenic carbon.

1-Silafluorene dianion was synthesized by potassium reduction of 1,1-dichloro-1-silafluorene in refluxing THF. The X-ray structure of 1,1-dipotassio-1-silafluorene (3b) shows C-C bond length equalization in the five-membered silole ring and C-C bond length alternation in the six-membered benzene rings, indicating aromatic delocalization of electrons in the silole ring. The downfield (29)Si chemical shift at 29.0 ppm and theoretical calculations also support electron delocalization in the silole ring of 3b. Dianion salt 3b underwent nucleophilic reactions with Me(3)SiCl and EtBr to form the corresponding disubstituted products. Benzaldehyde underwent reductive coupling in the presence of 3b. Slow oxidation of 3b yielded 1,1'-dipotassio-1,1'-bis(silafluorene) (16). The X-ray structure and (29)Si chemical shift (-38.0 ppm) of 16 indicate localized negative charges at the silicon atoms and no aromatic character. Heating a DME/hexane solution of 3b in the presence of 18-crown-6 led to a novel diradical dianion salt.