Chemistry - STEREO ISOMERISM Question with Solution | TestHub

An axial methyl at C-1 is gauche to the ring along both the ${\mathrm{C}}_1-{\mathrm{C}}_2$ bond ($\mathrm{Me}-{\mathrm{C}}_1-{\mathrm{C}}_2-{\mathrm{C}}_3$) and the ${\mathrm{C}}_1-{\mathrm{C}}_6$ bond ($\mathrm{Me}-{\mathrm{C}}_1-{\mathrm{C}}_6-{\mathrm{C}}_5$) : two gauche-butane interactions, 2 × 3.8 = 7.6 kJ/mol - exactly the measured A-value of methyl.