A method of synthesizing a directly connected 1,3a,6a‐triazapentalene (TAP) ring system as a linearly bonded aromatic system with a planar form was established. Various TAP‐dimers and a 2‐alkyl‐TAP‐trimer were synthesized and their fluorescence properties were evaluated. Although the direct connection of the TAP ring with other TAP rings did not affect the fluorescence properties in diluted solvent, TAP‐dimers showed unique fluorescence properties derived from the aggregation state under highly concentrated conditions. In particular, TAP‐dimer 5 f showed aggregation‐induced emission in highly concentrated solution, and 5 b showed typical mechanochromic fluorescence in the solid state despite their compact molecular size.
Palau’amine has received a great deal of attention as an attractive synthetic target due to its intriguing molecular architecture and significant immunosuppressive activity, and we achieved its total synthesis in...
The
first total syntheses of two 4,10-dihydroxy-8,12-guaianolides
that were reported to be natural products were achieved. Toward the
syntheses of a collection of related guaianolides, the typical 5,7-fused
system of 8,12-guaianolides was constructed by a ring expansion reaction
of a hydroxylated coronafacic acid analogue that can be practically
synthesized and optically resolved. The total syntheses of these compounds
revealed that the previously reported structures of both natural products
were incorrect.
1,3a,6a‐Triazapentalene (TAP) is a compact fluorescent molecule consisting of a triazabicyclo[3.3.0]octane skeleton. In this work, a method of synthesizing a directly connected TAP ring system as a linearly bonded aromatic system with a planar form was established. The TAP‐bonded system showed interesting fluorescence properties resulting from changes in aggregation state at high concentration and solid state. In particular, solids of some TAP‐bonded systems showed changes in fluoresence color by grinding, that is, typical mechanochromic fluorescence properties were observed. The cover picture shows that fluorescence is emitted when the DJ scrapes the TAP‐bonded system represented by disks. More information can be found in the Full Paper by K. Namba et al. on page 17727.
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