Compound A on oxidation with `OsO_4//NaHSO_3` following by reaction with `HIO_4` gives hexane 1,6 - di al .The structure of compound A can be given as

Options

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B.
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D.

Answer

To determine the structure of compound A that leads to hexane-1,6-dial upon oxidation with OsO4 followed by reaction with HIO4, we can follow these steps:

### Step 1: Understand the Reactions
- **OsO4 Reaction**: OsO4 (osmium tetroxide) is used to oxidize alkenes to form diols (vicinal diols). This means that compound A must be an alkene that can undergo syn-dihydroxylation.
- **HIO4 Reaction**: HIO4 (periodic acid) cleaves diols into aldehydes or ketones. In this case, it will cleave the diol formed from the previous step.

### Step 2: Identify the Product
- The final product is hexane-1,6-dial, which has the structure:
```
CH3-CH2-CH2-CH2-CHO
```
This indicates that the original compound A must have a structure that allows for the formation of this product after the reactions.

### Step 3: Determine the Structure of Compound A
- To produce hexane-1,6-dial, we need to consider the cleavage of a diol that would lead to two aldehyde groups at the ends of a six-carbon chain.
- The diol that would yield hexane-1,6-dial upon cleavage would be a compound with two hydroxyl groups on the 1st and 6th carbon after the oxidation step.

### Step 4: Construct Compound A
- The structure of compound A must be an alkene that, after oxidation, would yield the required diol.
- The simplest alkene that can achieve this is 1,5-hexadiene:
```
CH2=CH-CH2-CH2-CH=CH2
```
- When this compound undergoes oxidation with OsO4, it will form a diol with hydroxyl groups on the 1st and 6th carbons.

### Final Structure of Compound A
Thus, the structure of compound A is:
```
CH2=CH-CH2-CH2-CH=CH2 (1,5-hexadiene)
```