Draw fisher projections for the two `D`-aldoheptose whose stereorientation at `C_(2),C_(3),C_(4),C_(5)` is same as that of `D-`glucose
at `C_(2),C_(3),C_(4)` and `C_(5)`.

Answer

To solve the problem of drawing Fischer projections for the two D-aldoheptoses whose stereochemistry at C2, C3, C4, and C5 is the same as that of D-glucose, we will follow these steps:

### Step 1: Draw the Fischer projection of D-glucose
1. Start by drawing the aldehyde group (CHO) at the top.
2. Below the aldehyde, draw the carbon chain with 7 carbons in total (C1 to C7).
3. For each of the stereocenters (C2, C3, C4, C5), place the hydroxyl (OH) groups according to the configuration of D-glucose:
- C2: OH on the right
- C3: OH on the right
- C4: OH on the left
- C5: OH on the right
4. The last carbon (C7) will have a CH2OH group.

### Fischer Projection of D-glucose:
```
CHO
|
C1
|
C2 - OH
|
C3 - OH
|
C4 - H
|
C5 - OH
|
C6 - H
|
C7 - CH2OH
```

### Step 2: Draw the first D-aldoheptose
1. The first D-aldoheptose will have the same configuration at C2, C3, C4, and C5 as D-glucose.
2. Start with the aldehyde group (CHO) at the top.
3. For the carbon chain, keep the same stereochemistry:
- C2: OH on the right
- C3: OH on the right
- C4: OH on the left
- C5: OH on the right
4. At C6, we will place an OH group on the left side (this is the variation).
5. The last carbon (C7) will still have a CH2OH group.

### Fischer Projection of the first D-aldoheptose:
```
CHO
|
C1
|
C2 - OH
|
C3 - OH
|
C4 - H
|
C5 - OH
|
C6 - OH
|
C7 - CH2OH
```

### Step 3: Draw the second D-aldoheptose
1. Start with the aldehyde group (CHO) at the top.
2. For the carbon chain, keep the same stereochemistry:
- C2: OH on the right
- C3: OH on the right
- C4: OH on the left
- C5: OH on the right
3. At C6, we will place an OH group on the right side (this is the variation).
4. The last carbon (C7) will still have a CH2OH group.

### Fischer Projection of the second D-aldoheptose:
```
CHO
|
C1
|
C2 - OH
|
C3 - OH
|
C4 - H
|
C5 - OH
|
C6 - H
|
C7 - CH2OH
```

### Summary of the Fischer Projections:
- The first D-aldoheptose has the OH group on the left at C6.
- The second D-aldoheptose has the OH group on the right at C6.