Which of the following additions to alkenes occur(s) specifically in an syn fashion? A) dihydroxylation using Os04, H202
B) addition of H2
C) hydroboration
D) addition of HCI
E) A, B, and C

Dihydroxylation using Os04, H202, Addition of H2 and Hydroboration to

alkenes occur in a syn fashion.

Syn addition refers to the addition of two substituents( compounds) on the

same side thereby increasing the number of substituents and a decrease in

the bond order.

Hydrogenation, hydroboration and dihydroxylation all undergo syn addition which is the addition of the substituent to the same side which is why it is the right choice.

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E) A, B, and C

Explanation:

Syn addition refers to the addition of two substituents on the same face or side of a double bond. This differed from anti addition which a occurs across opposite face of the double bond.

Hydrogenation, hydroboration and dihydroxylation all involve syn addition to the double bond, hence the answer chosen above.