A Convenient Synthesis of Symmetric 1,2-Diarylethenes from Arylmethyl Phosphonium Salts

Abstract

Symmetric ethenyldithiophenes are important intermediates for synthesis of photochromic materials and organic conductors. When acetonitrile is used as a solvent, 3-methylthiophenylphosphonium salts form symmetric ethenyldithiophenes in the presence of a strong base (e.g., NaH, (t)BuOK) in moderate to high yields. This homocoupling reaction is faster than a Wittig reaction with aromatic ketones in acetonitrile. Our study shows that the presence of polar aprotic solvents promotes the homocoupling reaction.

Stabilising fleeting intermediates of stilbene photocyclization with amino-borane functionalisation: the rare isolation of persistent dihydrophenanthrenes and their [1,5] H-shift isomers

“…The ylide reagents were synthesized according to the relevant literature. 9 – 13 BO-1 was prepared according to a procedure we developed recently. 14 BO1′ and BO1m were prepared according to procedures outlined in the ESI.…”

“…All starting materials were purchased from Energy Chemical. (Pyridin-2-ylmethyl)triphenylphosphonium chloride, 9 2-metho-xybenzyltriphenylphosphonium chloride, 10 benzylphosphonium bromide, 11 2-thienylmethyltriphenylphosphonium chloride, 12 3-thienylmethyltriphenylphosphonium bromide, 13 2-dimesityl-borylbenzaldehyde, 22 2-bromo-4-(dimethylamino)benzalde-hyde, 23 and 5-bromo-2-(dimethylamino)benzaldehyde 24 were synthesized according to procedures reported in literature. The starting materials for E -8a and E -9a ( BO1′ and BO1m , respectively) were prepared according to procedures outlined in the ESI.…”

Main chain polymeric metal complexes based on linkage fluorenevinylene or phenylenevinylene with thienyl(8‐hydro xyquinoline)–cadmium (II) complexes as dye sensitizer for dye‐sensitized solar cells

“…2‐bromo‐3‐methylthiophene ( 1 ),44 2‐bromo‐3‐bromomethyl thiophene ( 2 ),45 5‐formyl‐8‐tosyloxy quinoline ( 4 ),46 1,4‐Divinyl‐2,5‐dioctyloxyl benzene ( M‐1 ),47 2‐methoxy‐5‐octyloxy‐1,4‐xylylene‐bis(triphenylphosphonium bromide) ( 6 ),48 and 2,7‐bis(triphenylphosphonium)‐9,9′‐dioctylfluorene dibromine ( 7 )48 were prepared according to known literature procedures. All initial materials were obtained from Shanghai chemical reagent Co. (Shanghai China), and were used without further purification.…”

E,Z-Selectivity in the reductive cross-coupling of two benzaldehydes to stilbenes under substrate control

“…Analytical data of the compounds are in agreement with the reported literature values. 54 The E/Z ratio was determined based on the characteristic olefinic signals of the two isomers. (E-Z) 1-Bromo-2-(4-methoxystyryl)benzene (Scheme 3a).…”