Synthesis of Ring-Locked Tetracyclic Dithienocyclopentapyrans and Dibenzocyclopentapyran via 1,5-Hydride Shift and Copper-Catalyzed C-O Bond Formation for Nonfullerene Acceptors.

We discovered a unique synthetic route to construct 2H-pyran-containing tetracyclic dithienocyclopentapyran (DTCP) and dibenzocyclopentapyran (DBCP) architectures. The synthesis involves an acid-induced dehydration cyclization followed by a [1,5] hydride-shift isomerization to form a cyclopentanone moiety which was converted to the pyran-embedded tetracyclic products by a CuI-catalyzed intramolecular C-O bond formation in good yield. DTCP was used as a building block to prepare an acceptor-donor-acceptor (A-D-A) type n-type material DTCP-BC leading to a solar cell efficiency of 9.

Recent Advances in Chiral Guanidine-Catalyzed Enantioselective Reactions.

Chiral guanidines have been widely used as Brønsted base catalysts and phase transfer catalysts in enantioselective reactions. Due to their amendable structure and powerful catalytic ability, they have attracted much interest. Several new catalysts containing a guanidinium moiety have been reported over the past decade and many promising outcomes have been achieved.

Regio- and stereo-selective [4+4] photodimerization of angular-shaped dialkyltetracenedithiophene.

Angular-shaped dialkyltetracenedithiophenes (aTDTs) undergo [4+4] photodimerization in solution to form a butterfly-shaped skeleton. This reaction proceeds in a regio- and stereo-selective manner, forming only a single planosymmetric syn-[2,2]-daTDT out of six possible products. The photocycloaddition of aTDTs can take place topochemically in the thin-film state while maintaining regio- and stereo-selectivity.

Synthesis and Isomeric Effects of Ladder-Type Alkylated Terbenzodithiophene Derivatives.

A new class of heptacyclic ladder-type terbenzodithiophene (TBDT) structures merging three fused benzodithophenes was developed. Two TBDT conjugated isomers, named as syn-TBDT and anti-TBDT, where the two thienyl rings in the outmost BDT units are in the syn- and anti-fashion, are designed. Two decyl groups are introduced to their 6,13 and 7,14-positions to form four isomeric 6,13-syn-TBDT, 7,14-syn-TBDT, 6,13-anti-TBDT, and 7,14-anti-TBDT structures which are constructed by the DBU-induced 6-benzannulation involving propargyl-allenyl isomerization of the dieneyne moieties in the corresponding precursors followed by 6π-electrocyclization/aromatization, while isomeric TD-syn-TBDT and TD-anti-TBDT with four decyl groups substituted at 6,7,13,14-positions are synthesized via palladium-catalyzed dialkylacetylene insertion/C-H arylation of the corresponding iodobiaryl precursors.