$C{H_3}\, - \,\,C{H_2}\, - \,\,C{H_2}\, - \,\,\mathop C\limits_{\mathop {||}\limits_{OHC\,\, - \,\,C\,\, - \,\,C{H_2}\, - \,\,C{H_3}} } \,\, - \,\,COOH$