Electric Literature of 21120-91-2, A common heterocyclic compound, 21120-91-2, name is 7-Bromobicyclo[4.2.0]octa-1,3,5-triene, molecular formula is C8H7Br, its traditional synthetic route has been very mature, but the traditional synthetic route has various shortcomings, such as complicated route, low yield, poor purity, etc, below Introduce a new synthetic route.
General procedure: In a 250 ml three necked round bottom flask equipped with a polytetraflouroethylene (Teflon polymer, Dupont, Wilmington, Del.) coated magnetic stir bar, potassium hydroxide (1.38 g, 1 eq) was dissolved in water (6.83 g). Then 4-acetoxy styrene (4 g, 1 eq) was added dropwise at room temperature, and the solution turned from colorless to pale orange. Potassium carbonate (6.82 g, 2 eq) was added portionwise, and the solution was stirred for one hour. The flask was equipped with a reflux condenser, then 1-bromobenzocyclobutene (4.06 g, 1 eq) was added dropwise in DMF (41 ml). The solution was then heated to 70 C. and allowed to reflux overnight. To the reaction was added water (50 ml) and ethyl acetate (50 ml). The aqueous residue was extracted four times with ethyl acetate (100 ml). The combined organics were extracted with sodium bicarbonate solution (1¡Á100 ml), lithium chloride aqueous solution (1¡Á100 ml) and brine (2¡Á100 ml). The organics were dried over sodium sulfate, filtered and concentrated in vacuo to give the product as a of white solid (3.36 g, 68% yield). Melting point 54-60 C. 1H NMR (600 MHz, Chloroform-d) delta 7.39 (d, J=8.6 Hz, 2H), 7.34 (td, J=7.3, 1.5 Hiz, 1H), 7.31-7.24 (m, 2H), 7.21-7.18 (m, 1H), 6.98 (d, J=8.6 Hz, 2H), 6.69 (dd, J=17.6, 10.9 Hz, 1H), 5.70 (dd, J=4.3, 1.9 Hz, 1H), 5.64 (dd, J=17.6, 0.9 Hz, 1H), 5.15 (dd, J=10.9, 0.9 Hz, 1H), 3.73 (dd, J=14.2, 4.3 Hz, 1H), 3.31 (d, J=14.2 Hz, 1H). 13C NMR (151 MHz, Chloroform-d) delta 157.79, 144.62, 142.57, 136.20, 130.87, 129.93, 127.50, 127.43, 123.48, 123.04, 115.06, 111.80, 74.28, 39.45. Yield from the above example was good and the resulting monomer was a stable solid which has a desirable ring opening cure temperature of 184 C.
The basis of chemical reaction formula synthesis, the synthesis route is composed of some specific reactions and combined according to certain logical thinking. We look forward to the emergence of more reaction modes in the future.
Reference:
Patent; Rohm and Haas Electronic Materials LLC; Hayes, Colin; Gallagher, Michael K.; Riener, Michelle; (10 pag.)US2019/169327; (2019); A1;,
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