This invention relates to novel compounds of formula (I) wherein R1 represents a polymer, aryl or alkyl group, R2 represents a hydrogen atom, a halogen atom, a radical CN, CF3, OH, OCF3, COOH, R7, OR7 or OCOR7, R3 represents an aryl or alkyl halogen, R4 represents an alkyl radical. The invention also relates to a cosmetic composition comprising said compounds and to the use thereof to reduce and/or curb hair loss i.e. to increase and/or stimulate the growth of said hair.