1) the hydroboration of norbornene (1) with either borane or 9-bbn produces almost entirely the exo-alcohol 2, and only a trace of endo alcohol 3 (eq 1). in comparison, the hydroboration of the 7,7-dimethyl analogue 4 favors the endo-alcohol 5 over the exo alcohol 6 by 78: 22, a ratio that can be further increased with 9-bbn (eq 2). explain why the methyl substitution on the norbornene skeleton switches the regioselectivity to favor the eno alcohol, and why 9-bbn further enhances this selectivity. 2) what’s the mechanism of the following reaction? start by identifying which c-c bonds need to be formed. [h+] means any strong acid source to promote the reaction