import re s = '\\(2 \\, e^{\\left(2 \\, x\\right)} \\sin\\left(2 \\, x\\right) + 2 \\, e^{\\left(2 \\, x\\right)} \\cos\\left(2 \\, x\\right)\\)' print(re.sub(r'e\^{\\left\((.*?)\\right\)}', r'e^{\1}', s))