2,5-Bis-Thiopheneboronic acid pinacol ester

To a solution of 2, 5-dibromothiophene (2.0 g, 8.3 mmol) in dry THF (40) was addedn-BuLi (15 mL, 1.6 M solution in hexane, 25 mmol) dropwise at -78 °C and the mixturewas stirred for 1 h at the same temperature. Tributylborate (6.4 mL, 25 mmol) wasadded to the reaction mixture at -78 °C and the mixture was gradually warmed to roomtemperature. After stirred for additional 2 h, pinacol (3.8 g, 33 mmol) and acetic acid(1.4 mL, 25 mmol) were added to the mixture and the resulting mixture was stirred atambient temperature for 14 h. The solution was filtered through a celite pad and thefiltrate was evaporated in vacuo. The residue (a brown soild) was purified byrecrystallization from ethyl acetate and hexane solution to give the titled compound (2.0g, 75percent) as a white solid- Borylation of Aromatic Five-Membered Heterocycle According to the reaction scheme illustrated in Figure 2(a), a scintillation vial (with a magnetic stir bar) was charged with cobalt complex (0.01 mmol) selected from 1-4, 2 methylfuran (1 mmol) and pinacolborane (1 mmol). The reaction was monitored by the analysis of an aliquot of the mixture by GC-FID. The mixture was allowed to stir to completion at room temperature and was quenched by exposure to air. The resulting solid was solubilized in CDC1General procedure: In a glovebox filled with nitrogen, [Ir(OMe)(cod)]2 (33.1 mg, 0.050 mmol, 0.10 equiv), ICy·HCl(26.2 mg, 0.10 mmol, 0.20 equiv), NaOt-Bu (19.2 mg, 0.20 mmol, 0.40 equiv) andmethylcyclohexane (1.0 mL) were added to a 10 mL-sample vial with a Teflon-sealed screwcap, andstirred for 5 min at room temperature. A heteroarene (0.50 mmol, 1.0 equiv) and 1g (113.1 mg, 2.0equiv) were added, and then the cap was screwed on seal the vial. The vial was stirred at 110 °C for4 h. The reaction mixture was cooled to room temperature. Pinacol (236 mg, 2.0 mmol) in THF (2.0mL) was added and the reaction mixture was stirred under N2 at room temperature for 1.5 h. Thecrude mixture was filtered through a pad of Celite and eluted with EtOAc. The filtrate wasconcentrated in vacuo and sampled for analysis by 1HNMR spectroscopy using 1, 2-dichloroethaneas an internal standard. The residue was purified by flash column chromatography over silica geleluting with hexane/EtOAc. Product-containing fractions were concentrated in vacuo to give a pureborylated product.In a reaction flask charged with Pd(OAc)In a reaction flask charged with Pd(OAc)Example 17 Bis(pinacolate)diboron (1.1 mmol), thiophene (1.0 mmol), IrCl(COD) (0.03 mmol), dtbpy (0.03 mmol) and 6 ml of octane were mixed followed by stirring while heating for 16 hours at 80C. After allowing to cool to room temperature, the mixture was diluted with toluene and washed with saturated saltwater. The organic layer was concentrated under reduced pressure followed by distilling off the residue to obtain 0.8 mmol of 2, 5-bis(4, 4, 5, 5-tetramethyl-1, 3, 2-dioxaborolan-2-yl) thiophene. 1H-NMR (400 MHz, CDCl3, TMS): delta 1.34 (s, 24H), 7.67 (s, 2H) 13C-NMR (100 MHz, CDCl3, TMS): delta 24.74, 84.11, 137. 66 MS m/e: 43(50), 59(27), 237(43), 250(100), 321(32), 336(M+, 55) Exact mass calculated for C16H26B2O4S: 336.1738, found: 336.1750General procedure: Preparation of 5a is described as a typical procedure. To a 1, 4-dioxane solution (34 mL) of bromide 4a(1.11 g, 5.07 mmol) and PdCl2(PPh3)2 (70 mg, 0.10 mmol) were added 3-thienylboronic acid 1a (702 mg, 5.48 mmol), Na2CO3 (1.06 g, 10.0 mmol), and distilled water (17 mL). The reaction mixture wasfreeze-dried and refluxed overnight. Saturated aqueous NH4Cl (50 mL) was added to quench the reactionat room temperature. Organic materials were extracted with Et2O (15 mL) three times. The combinedextracts were washed with brine and dried over anhydrous Na2SO4. After removal of the solvent underreduced pressure, the residue was purified by column chromatography on silica gel (hexane) to givedifluoroalkene 5a (871 mg, 76% yield) as a colorless liquid.(10) (45.4 mg, 0.135 mmol), 2-bromo-4-Methyl-3-(3-(pyren-1-yl)tetraethoxy)thiophene (9) (80.7 mg, 0.140 mmol) [34], 2-bromo-4-methyl-3-(3-(1-(5-phenyl-10, 15, 20-triphenylporphyrin))tetraethoxy)thiophene (13) (132.5 mg, 0.135 mmol), tetramethylammoniumbromide (ca.) and Na2CO3 (7.1 mg, 0.067 mmol) (2 M) weredissolved in 30mL of anhydrous toluene. The solution was purgedwith nitrogen for 20 min; then bis(triphenylphosphine)palladium(II) dichloride (4.7 mg, 0.0067 mmol) was added and the reactionmixture was heated with vigorous stirring at 80 C. The reactionprogress was followed by TLC. After 24 h, the mixture was cooled toroom temperature and extracted with dichloromethane. The extractswere washed with saturated brine and dried over Na2SO4.The crude productwas purified by column chromatography in silicagel, employing chloroform:hexanes 80:20 as eluent to obtainTT4PY-PPh (147 mg). Yield: 74%.1H NMR (CDCl3, 400 MHz, ppm): 8.85 (d, 2H, Hd, J = 6.0 Hz), 8.83(s, 6H, Hd), 8.60-7.29 (27H, pyrene and phenyl rings) 7.01 (d, 2H, Ha, J= 4.1 Hz), 6.88 (m, 2H, Hb), 4.5-3.66 (32H, O-CH2), 2.19 (s, 6H, CH3), 2.79 (s, 2H, NH).MS (MALDI-TOF): m/z calculated for C90H80N4O10S3 [M]+:1473.81; Found: 1473.63.This trimer was prepared using a procedure that is similar to theone described by Duddukuri [40]. Under nitrogen atmosphere, the intermediate B3 (2.4 g, 9.7 mmol, 2.6 eq.), Thiophene-2, 5-diboronic acid dipinacol ester (1.3 g, 3.9 mmol), palladium acetate (0.02 g, 0.089 mmol, 1% Pd), 2, 6-dimethoxy-2'-dicyclohexylphosphinobiphenyl (0.1 g, 0.24 mmol, 2.7 eq. to Pd), potassium phosphate (3.3 g, 16 mmol, 4 eq .) Was suspended in a mixed solvent of toluene (20 ml) and water (2 ml), and the mixture was stirred at 80 C. for 10 hours.The reaction mixture was diluted with toluene (100 ml), the supernatant was taken, dried over anhydrous magnesium sulfate and evaporated to give a brown oil. This was purified by column chromatography (silica gel / hexane + 5% ethyl acetate) to obtain Intermediate B4 (1.4 g, 70%) as a yellow oil.

Molecular Weight:336.1
Hydrogen Bond Acceptor Count:5
Rotatable Bond Count:2
Exact Mass:336.1737908
Monoisotopic Mass:336.1737908
Topological Polar Surface Area:65.2
Heavy Atom Count:23
Complexity:407
Covalently-Bonded Unit Count:1
Compound Is Canonicalized:Yes