Coupler for use in oxidative hair dyeing
View Patent ↗Couplers for hair coloring compositions for oxidative dyeing of hair are compounds of formula (1): wherein X is selected from halogen; R 3 is selected from the group consisting of C 1 to C 2 alkyl and hydroxyethyl; and R, R 1 and R 2 are each independently selected from C 1 to C 22 alkyl or C 1 to C 22 mono or dialkyl groups, or two of R, R 1 and R 2 together with the the nitrogen atom to which they are attached form a C 3 to C 6 cycloaliphatic or a C 3 to C 14 aromatic group, the cycloaliphatic or aromatic group optionally containing in their rings one or more hetero atoms selected from O, S and N atoms.
1. A compound of formula (1):
wherein X is selected from the group consisting of halogen: R 3 is selected from the group consisting of C 1 to C 2 alkyl and hydroxyethyl; and R, R 1 and R 2 are each independently selected from the group consisting of C 1 to C 22 alkyl or C 1 to C 22 mono or dialkyl groups, or two of R, R 1 and R 2 together with the the nitrogen atom to which they are attached form a C 3 to C 6 cycloaliphatic or a C 3 to C 14 aromatic group, the cycloaliphatic or aromatic group optionally containing in their rings one or more hetero atoms selected from O, S and N atoms.
2. A compound of claim 1 wherein X is selected from the group consisting of Cl, Br, and I; and two of R, R 1 and R 2 together with the nitrogen atom to which they are attached form an C 3 to C 6 cycloaliphatic or C 3 to C 6 aromatic group optionally containing in the ring another N atom.
3. A compound of claim 2 wherein X is Cl.
4. A compound of claim 3 wherein R 3 is methyl.
5. A compound of claim 4 wherein two of R, R 1 and R 2 together with the nitrogen atom to which they are attached form an imidazoline ring.
6. A compound of claim 4 wherein two of R, R1 and R2 together with the nitrogen atom to which they are attached form a piperazine ring.
7. A process for the preparation of a compound of claim 1 comprising reacting an aminophenol of the formula (2):
with a haloacetyl chloride to produce a compound of formula (5)
reducing compound (5) with a borane-tetrahydrofuran complex to produce a compound of formula (6)
and reacting the compound of formula (6) with a reagent of the formula N(R 1 )(R 2 )(R 3 )to produce a compound of formula (1)
wherein X, R, R 1 , R 2 and R 3 are as defined in claim 1 .
8. A process according to claim 7 wherein X is selected from the group consisting of Cl, Br, and I; and two of R, R 1 and R 2 together with the nitrogen atom to which they are attached form an C 3 to C 6 cycloaliphatic or C 3 to C 6 aromatic group optionally containing in the ring another N atom.
9. A process according to claim 8 wherein X is Cl; R 3 is methyl; and the other of R, R 1 and R 2 not forming the cycloaliphatic or aromatic group is methyl.
10. A process according to claim 7 wherein the reducing agent is selected from the group consisting of sodium borohydride and sodium triacetoxyborohydride.