A High-Yield Route to 2,5-Di-n-alkyl-1,4-benzenedicarboxylic Acids

New photoluminescent conjugated polymers with 1,4-dioxo-3,6-diphenylpyrrolo[3,4-c]pyrrole (DPP) and 1,4-phenylene units in the main chain

“…The general synthetic procedure is outlined in Scheme 3. The copolymers were obtained by reacting mixtures of the two dibromocompounds 2 and 1,4-dibromo-2,5-dihexylbenzene 22) in different ratio with 2,5-dihexylbenzene-1,4-diboronic acid using the same conditions as for polymer 3 (Scheme 2). As a reference material, the DPP-free homopolymer 5 was also prepared by coupling of 1,4-dibromo-2,5-dihexylbenzene and 2,5-dihexylbenzene-1,4-diboronic acid, again under the same conditions as for 3.…”

Synthesis of Monodisperse Oligo(para-phenyleneethynylene)s Using Orthogonal Protecting Groups with Different Polarity for Terminal Acetylene Units

“…Cl 2 ) as a function of the reciprocal number of repeating units; data for 10, [3] 11, [4,12] and 12 [4] are taken from the literature; only Figure 1. (a) Absorption and (b) emission spectra of oligomers 1a, 1b, 1d, and 1f in CH 2 Cl 2 ; λ excitation ϭ 295, 330, 340, and 360 nm for reasons of clarity, the data points of each class of compounds were connected by a line for 1a, b, c, and d 1,4-Dihexyl-2,5-diiodobenzene (8): [18] A mixture of 1,4-dihexylbenTo study the dependence of λ on the rod length for oligzene [19] (25.0 g, 101 mmol), iodine (28.32 g, 112 mmol), KIO 3 oPPEs with different end groups, the absorption energy E (10.85 g, 50 mmol) in acetic acid (300 mL), conc. H 2 SO 4 (20 mL), was plotted as a function of n Ϫ1 , with n being the number and water (3 mL) was refluxed for 18 h. The reaction mixture was of repeating units ( Figure 3).…”

Development of an Unusually Highly Enantioselective Hetero-Diels-Alder Reaction of Benzaldehyde with Activated Dienes Catalyzed by Hypercoordinating Chiral Aluminum Complexes

“…Kumada coupling [15] of heptylmagnesium bromide with 10 using [Ni(dppp)Cl 2 ] (dppp 1,3-bis(diphenylphosphino)propane) in refluxing Et 2 O gave 1,4-diheptylbenzene (11), [16] which was dibrominated in a solvent-free reaction catalyzed by I 2 to give 1,4-dibromo-2,5-diheptylbenzene (12) in 76 % yield, using a modified procedure adopted from Schlüter et al [17] Selective monolithiation of 12 using nBuLi followed by quenching with NH 4 Cl at À 78 8C produced 1-bromo-2,5-diheptylbenzene (12 b) in quantitative yield. The crude product was resubjected to halogen ± lithium exchange using nBuLi (1.2 equiv) in Et 2 O, and the resulting monolithio compound was treated with B(OEt) 3 , and after completion of the reaction and an acidic workup, the boronic acid 13 was isolated in 90 % yield (Scheme 2).…”