Processes for producing 4-bromo-2-methoxybenzaldehyde
A new synthesis of 4-bromo-2-methoxybenzaldehyde is reported from 1,4 dibromo 2-fluorobenzene. First, 2-fluoro-4-bromobenzaldehyde is prepared through metal halogen exchange and formylation with a formyl source at 0° C. After crystallization, this intermediate is reacted with methanol in the presence of potassium carbonate. Subsequently, 4-bromo-2-methoxy-benzaldehyde is crystallized.
1. A process comprising:
(i) combining at least 1,4-dibromo-2-fluorobenzene, isopropyl magnesium chloride, THF and a first solvent to form a first combination;
(ii) combining at least the first combination, a formyl source, and a second solvent to form a second combination;
(iii) crystallizing a first solid intermediate from the second combination using a crystallization agent;
(iv) combining at least the solid intermediate, a third solvent comprising methanol, and a carbonate to form a third combination;
(v) distilling substantially all of the third solvent from the third combination;
(vi) combining the distilled third combination and isopropyl alcohol or one or more alkanes comprising heptane or to form a fourth combination; and
(vii) yielding 4-bromo-2-methoxybenzaldehyde from the fourth combination.
2. The process of claim 1 wherein the first solvent of (i) comprises toluene, methyl tent-butyl ether, 2-methyl, heptane, methyl cyclohexane, or hexane.
3. The process of claim 1 wherein the combining of (i) is conducted between about 0° C. to about 5° C.
4. The process of claim 1 wherein the second solvent of (ii) comprises toluene, methyl tert-butyl ether, 2-methyl, heptane, methyl cyclohexane, or hexane.
5. The process of claim 1 wherein the combining of (ii) is conducted between about 0° C. to about 5° C.
6. The process of claim 1 wherein the formyl source of (ii) comprises dimethyl formamide or N-formyl secondary amine.
7. The process of claim 1 wherein the crystallization agent of (iii) comprises heptane, cyclohexane, methyl cyclohexane, octane, pentane, or hexane.
8. The process of claim 1 wherein the carbonate of (iv) comprises potassium carbonate, sodium carbonate, or cesium carbonate.