(9,9-Dimethyl-9H-fluoren-2,7-diyl)diboronic acid

Off-white powder

2, 7-dibromo-9, 9-dimethylfluorene (14.8 g, 42.4 mmol)Add to three bottles, 100 mL of THF was added, Nitrogen protection, -78 deg.] C for 30 minutes, Then, 21 mL of n-butyllithium (2.5 M)Reaction for 1 hour, againAdd triisopropyl borate 14g, Low temperature reaction for 1 hour, Gradually restored room temperature.After the addition of 2M hydrochloric acid to the solution, the pH value of the solution was 4-5, and the aqueous layer was extracted with ethyl acetate. The organic layer was combined and dried to give intermediate A1 (9.5 g, yield 80percent ).(4-2) Synthesis of Intermediate 8; Into a 3 liter three-necked flask, 35 g (0.1 mole) of Intermediate 7 and 1 liter of THF were placed under the stream of argon, and the obtained solution was cooled at -65° C. To the cooled solution, 220 ml of a solution of n-butyllithium (0.22 moles, a 1 mole/liter hexane solution) was slowly added. After the reaction fluid was stirred at -70° C. for 6 hours, 45 g (0.24 moles) of boronic acid triisopropoxide was slowly added at -65° C. The resultant fluid was stirred at -70° C. for 1 hour and then at the room temperature for one night. After the reaction was completed, dilute hydrochloric acid was added to the reaction fluid to adjust pH at 3, and the organic layer was separated, washed with a saturated aqueous solution of sodium chloride and dried with magnesium sulfate. The solvent was removed by distillation using a rotary evaporator, and ethyl acetate was added to the residue. The obtained crystals were separated by filtration and washed with hexane three times, and 20 g of Intermediate 8 of the object compound was obtained (white crystals; the yield: 70percent).In a stream of argon, 35 g (0.1 mol) of Intermediate 6 and 1 L of tetrahydrofuran (THF) were added to a 3-L three-necked flask, and the whole was cooled to - 65°C. Subsequently, 220 mL (0.22 mol, 1 mol/L (hexane)) of n-butyllithiumwere slowlyaddedto the resultant. After the reaction liquid had been stirred at - 70°C for 6 hours, 45 g (0.24 mol) of boronic triisopropoxide were slowly added to the reaction liquid at - 65°C, and the whole was stirred at - 70°C for 1 hour. After that, the resultant was stirred at room temperature overnight. After the completion of the reaction, dilute hydrochloric acid was added to the reaction liquid to adjust the pH of the liquid to 3, and an organic layer was separated and washed with a saturated salt solution. After the washed product had been dried with magnesium sulfate, the solvent was removed by distillation with a rotary evaporator, and ethyl acetate was added to the remainder. The resultant crystal was separated by filtration, and was washed with hexane three times, whereby 20 g of Intermediate 7 (white crystal, 70percent yield) as a target were obtained.Dibromo-9, 9-dimethylfluorene (14.9 g, 42.4 mmol) was added to a three-necked flask and 100 mL of THF was added thereto and protected by nitrogen. The mixture was stirred at -78 ° C for 30 minutes and then n-butyllithium M) 21 mL, reacted for 1 hour, added triisopropyl borate 14 g, reacted at low temperature for 1 hour, and gradually returned to room temperature.In the post-treatment process, 2M hydrochloric acid was added to the system to make the solution have a pH of 4-5, and the mixture was allowed to stand for liquid separation. The aqueous layer was extracted with ethyl acetate, and the organic layers were combined and spin-dry.2, 7-Diboronic acid-9, 9-dimethylhydrazine (8.9 g, 75percent yield) was obtained.

Molecular Weight:281.9
Hydrogen Bond Donor Count:4
Hydrogen Bond Acceptor Count:4
Rotatable Bond Count:2
Exact Mass:282.1234693
Monoisotopic Mass:282.1234693
Topological Polar Surface Area:80.9
Heavy Atom Count:21
Complexity:354
Covalently-Bonded Unit Count:1
Compound Is Canonicalized:Yes