A IChO-2014 problem involving reaction mechanism This is a problem of IChO-2014(&amp;solution).But I am having trouble working out reaction mechanism of the second reaction or even how the product B formed. This reaction is somewhat new to me. And googling didn't help much.

Just need a little hint on this regard.
A to B is a classic hydroboration of the least hindered double bond followed by oxidation of the trialkyl borane.