Preparation of (R,R)-(-)-2,3-bis(T-tert-butylmethylphosphonium)quinoxaline_Industrial additives

Background and overview^[1]

(R,R)-(-)-2,3-bis(t-tert-butylmethylphosphonium)quinoxaline is a metal coordination compound that can provide excellent catalytic performance. Organic synthesis reactions using metal coordination compounds having optically active phosphine ligands as catalysts are extremely useful reactions known in the art.

Preparation^[1]

Synthesis of (R, R)-epoxy soybean oil price 2,3-bis(t-tert-butylmethylphosphino)quinoxaline (a3)

After nitrogen replacement of the fully dried 300 mL four-necked flask, 111.46 g (135.0 mmol) of the tetrahydrofuran solution of 14.2 mass % (S)-tert-butylmethylphosphine-borane (a2) prepared above was added. After cooling to -10° C. under a nitrogen atmosphere, 59.3 g of a 15 mass% hexane solution of n-butyllithium was added dropwise over 1 hour. Then, it was aged at -10°C for 1 hour, and this was used as liquid B.

In addition, prepare a fully dried 2000mL four-necked flask. After nitrogen replacement, add 8.97g of 2,3-dichloroquinoxaline (a1) (45.0mmol antioxidant manufacturer), tetrahydrofuran (81ml), N, N- 90 ml of dimethylformamide, cooled to -10°C, and used as liquid A.

Add liquid B to liquid A at a constant rate over 40 minutes so that the internal temperature is maintained at about -10°C. The white slurry temporarily changes to green, and finally forms a black brown slurry.

After the dropwise addition is completed, slowly raise the temperature to room temperature (25°C), and then mature for 3 hours. Then, 52.6 g (450.0 mmol) of tetramethylenediamine was added, and the mixture was continuously matured overnight. The deboranization reaction was fully carried out to form an orange slurry.

Next, 180 mL of 10 mass% hydrochloric acid was added to terminate the reaction, and the aqueous layer was discarded. Then, 45 mL of water and 17 mL of 5 mass% hydrochloric acid were added, the reaction solution was washed, and the water layer was discarded. Next, 45 mL of 2.5% by mass sodium bicarbonate aqueous solution and 45 mL of water were added in sequence, the reaction solution was washed, the water layer was discarded, and the solvent was removed using a vacuum pump to solidify the entire solution. After adding 90 mL of methanol and raising the temperature to completely dissolve it, it was slowly cooled to precipitate orange crystals. After washing with cold methanol, it was dried under pressure to obtain (R, R)-2,3-bis(t-tert-butylmethylphosphino)quinoxaline (a3) ​​(10.58 g, yield 70.3%). According to ³¹P NMR, the crystal has a purity of 99.0%, and the optical purity is 99.5%ee or more.

Identification data of (R,R)-(-)-2,3-bis(t-tert-butylmethylphosphonium)quinoxaline

Melting point: 102～103℃,

Specific optical rotation [α]D26-54.5 (c 1.00, CHCl₃),

¹H NMR (500.15MHz, CDCl₃): δ1.00-1.03(m, 18H), 1.42-1.44(m, 6H), 7.70- 7.74(m,2H),8.08-8.12(m,2H),

¹³C NMR (125.76MHz, CDCl₃): δ4.77 (t, J=4.1Hz), 27.59 (t, J=7.4Hz), 31.90 (t, J=7.4Hz), 129.50, 129.60, 141.63, 165.12 (dd, J=5.7, 2.4Hz),

³¹P NMR (202.46MHz, CDCl₃): δ-16.7(s)