Palladium(II) Acetate (Purified)

Used Chemicals

• 3-Iodobenzalehyde [I0611]
• Bis(pinacolato)diborane [B1964]
• Palladium(II) Acetate (Purified) [P2161]
• Potassium Acetate [P2786]
• DMF

Procedure

To the solution of 3-iodobenzalehyde (1.16 g, 5.00 mmol) in dry DMF (15.0 mL) were added potassium acetate (981 mg, 10.0 mmol), palladium(II) acetate (112 mg, 0.500 mmol, 10 mol%) and bis(pinacolato)diborane (1.27 g, 5.00 mmol). The reaction mixture was stirred at 80 ºC for 7 h. The reaction mixture was cooled to room temperature and quenched with H₂O (15 mL) and saturated NH₄Cl aq. (10 mL), then the mixture was extracted twice with hexane : EtOAc = 4 : 1. The combined organic layer was washed with H₂O (50 mL) and brine (50 mL), dried over Na₂SO₄, and concentrated under reduced pressure to afford the crude product as a yellow oil. The crude product was purified by column chromatography on silica-gel (hexane → hexane : EtOAc = 1:1) to afford 3-formylphenylboronic acid pinacol ester as a yellow oil (500 mg, 2.15 mmol, 43%).

Experimenter's Comments

(1) DMF was dried over molecular sieves.

(2) Completion of the reaction was confirmed by TLC (hexane : EtOAc = 1 : 1, Rf = 0.30) and GC.

Analytical Data（3-Formylphenylboronic Acid Pinacol Ester）

¹H NMR (400 MHz, CDCl₃); δ 10.1 (s, 1H), 8.30 (s, 1H), 8.06 (d, J = 4.0 Hz, 1H), 7.99 (ddd, J = 1.6, 1.8, 7.8 Hz, 1H), 7.53 (t, J = 8.0 Hz, 1H), 1.37 (s, 12H).

Lead Reference

• The bulky side chain of antillatoxin is important for potent toxicity: rational design of photoresponsive cytotoxins based on SAR studies
  • K. Okura, S. Matsuoka, M. Inoue, Chem. Commun. 2013, 49, 8024.

Used Chemicals

• 4-Bromophenol [B0787]
• Styrene (stabilized with TBC) [S0095]
• Palladium(II) Acetate (Purified) [P2161]
• Tri(o-tolyl)phosphine [T1024]
• Triethylamine [T0424]

Procedure

To a solution of 4-bromophenol (1.5 g, 8.7 mmol) in triethylamine (10 mL), styrene (1.1 g, 10.8 mmol), tri(o-tolyl)phosphine (0.16 g, 0.52 mmol) and palladium(II) acetate (0.020 g, 0.087 mmol) were successively added at room temperature. The reaction mixture was stirred overnight at 100 °C under nitrogen atmosphere. To a 1 mol/L HCl aq. (100 mL) the reaction mixture was added below 15 °C. Then diethyl ether (100 mL) was added and the mixture was stirred for 10 min. The solution was partitioned and the water phase was extracted by diethyl ether (50 mL). Then combined organic layer was dried over sodium sulfate and filtered. The residue was recrystallized from toluene giving trans-4-hydroxystilbene as a pale brown solid (0.97 g, 57% yield).

Experimenter's Comments

The reaction mixture was monitored by ¹H NMR.

Analytical Data（trans-4-Hydroxystilbene）

¹H NMR (400 MHz, CDCl₃); δ 9.59 (s, 1H), 7.53 (d, J = 7.3 Hz, 2H), 7.42 (d, J = 8.2 Hz, 2H), 7.34 (dd, J = 7.8, 7.3 Hz, 2H), 7.22 (t, J = 7.3 Hz, 1H), 7.15 (d, J = 16.5 Hz, 1H), 7.01 (d, J = 16.5 Hz, 1H), 6.77 (d, J = 8.7 Hz, 2H).

¹³C NMR (101 MHz, CDCl₃); δ 157.3, 137.6, 128.7 (2 C), 128.5, 128.1, 127.9 (2 C), 127.0, 126.1 (2 C), 125.1, 115.6 (2 C).

Lead Reference

• Palladium-catalyzed vinylic substitution with highly activated aryl halides
  • C. B. Ziegler Jr., R. F. Heck, J. Org. Chem. 1978, 43, 2946.

Other References

• Advances in the Heck chemistry of aryl bromides and chlorides
  • N. J. Whitcombe, K. K. Hii, S. E. Giboson, Tetrahedron 2001, 57, 7449.

Used Chemicals

• Morpholine [M0465]
• 4-Chlorotoluene [C0297]
• Palladium(II) Acetate (Purified) [P2161]
• JohnPhos [D3387]
• Sodium tert-Butoxide [S0450]
• Toluene

Procedure

To a solution of sodium tert-butoxide (0.54 g, 5.6 mmol), palladium(II) acetate (4.5 mg, 0.020 mmol), and JohnPhos (0.012 g, 0.040 mmol) in toluene (8 mL) 4-chlorotoluene (0.51 g, 4.0 mmol) and morpholine (0.42 g, 4.8 mmol) were successively added at room temperature. The mixture was stirred under nitrogen atmosphere at room temperature for 1.5 days, then under reflux condition for 0.5 days. Diethyl ether (20 mL) was added to the reaction mixture and filtered through celite. Solvent was removed and the residue was purified by column chromatography (1:4 ethyl acetate / hexane on SiO₂), giving 4-(p-tolyl)morpholine as a pale brown solid (0.45 g, 63% yield).

Experimenter's Comments

The reaction mixture was monitored by ¹H NMR.

Analytical Data (4-(p-Tolyl)morpholine)

¹H NMR (400 MHz, CDCl₃); δ 7.10 (d, J = 8.2 Hz, 2H), 6.85 (d, J = 8.2 Hz, 2H), 3.87 (t, J = 4.6 Hz, 4H), 3.12 (t, J = 4.8 Hz, 4H), 2.28 (s, 3H).

¹³C NMR (101 MHz, CDCl₃); δ 129.9 (4 C), 116.2 (2 C), 67.1 (2 C), 50.1 (2 C), 20.6.

Lead Reference

• A Highly Active Catalyst for the Room-Temperature Amination and Suzuki Coupling of Aryl Chlorides
  • J. P. Wolfe, S. L. Buchwald, Angew. Chem. Int. Ed. 1999, 38, 2413.

Other References

• Simple, Efficient Catalyst System for the Palladium-Catalyzed Amination of Aryl Chlorides, Bromides, and Triflates
  • J. P. Wolfe, H. Tomori, J. P. Sadighi, J. Yin, S. L. Buchwald, J. Org. Chem. 2000, 65, 1158.

Used Chemicals

• 2-Chlorophenothiazine [C0248]
• Tributyl(2-thienyl)tin
• Palladium(II) Acetate (Purified) [P2161]
• 2-Dicyclohexylphosphino-2’,4’,6’-triisopropylbiphenyl (Xphos) [D5038]
• Cesium Fluoride [C2204]
• Toluene

Procedure

To a solution of palladium(II) acetate (44.9 mg, 0.200 mmol, 4 mol%), XPhos (143 mg, 0.300 mmol, 6 mol%), cesium fluoride (2.28 g, 15.0 mmol) and 2-chlorophenothiazine (1.17 g, 5.00 mmol) in toluene (15.0 mL) was added tributyl(2-thienyl)tin (2.24 g, 1.90 mL, 6.00 mmol) and the reaction solution was stirred at 80 ºC for 24 h. After reaction mixture was cooled to room temperature, dichloromethane (15 mL) and H₂O (15 mL) were added. Separated water phase was extracted with dichloromethane (15 mL) for 3 times. Combined organic layer was dried over MgSO₄ (10 g) and concentrated under reduced pressure to afford the crude product as a brown solid. Crude was purified by column chromatography on silica-gel (hexane: EtOAc = 50 : 1 ~ 5 : 1 → dichloromethane) to afford 2-(thiophen-2-yl)-10H-phenothiazine as a yellow solid (990 mg, 3.51 mmol, 70%).

Experimenter's Comments

Completion of the reaction was confirmed by TLC (Hexane:EtOAc = 10:1, Rf: S.M.=0.28 T.M.=0.18) and GC.

Analytical Data（2-(Thiophen-2-yl)-10H-phenothiazine）

¹H NMR (400 MHz, CDCl₃); δ 7.92 (brs, 1H), 7.42 (dd, J = 0.9, 5.0 Hz, 1H), 7.35 (dd, J = 0.9, 3.6 Hz, 1H), 7.08-7.13 (m, 2H), 6.94-7.03 (m, 4H), 6.73-6.82 (m, 2H).

Lead Reference

• Rapid Access to New Angular Phenothiazine and Phenoxazine Dyes
  • E. A. Onoabedje, U. C. Okoro, D. W. Knight, J. Heterocycl. Chem. 2017, 54, 206.

References

• 1) A Rational Pre-catalyst Design for Bis-Phosphine Mono-oxide Palladium Catalyzed Reactions
  • Y. Ji, H. Li, A. M. Hyde, Q. Chen, K. M. Belyk, K. W. Lexa, J. Yin, E. C. Sherer, R. T. Williamson, A. Brunskill, S. Ren, L. Campeau, I. W. Davies, R. T. Rucki, Chem. Sci. 2017, 2841.
• 2) Enantioselective Synthesis of Hemiaminals via Pd-Catalyzed C－N Coupling with Chiral Bisphosphine Mono-oxides
  • H. Li, K. M. Belyk, J. Yin, Q. Chen, A. Hyde, Y. Ji, S. Oliver, M. T. Tudge, L. Campeau, K. R. Campos, J. Am. Chem. Soc. 2015, 137, 13728.
• 3) Searching for Practically Useful P-Chirogenic Phosphine Ligands
  • T. Imamoto, Chem. Rec. 2016, 16, 2655.