Which of the following is known as `4H-`pyran?

Options

A.
B.
C.
D.

Answer

A

Explanation

Its common name is `4H-`pyran. The `4H` indicates that `C-4` is the `CH_(2)` group in the pyran ring:

Its oxa name is `1-`oxacyclohexa`-2,5-`diene

In compound `(3)`, the `2, 3-`dihydro portion of the name indicates that two hydrogen atoms have been added to `4H-`pyran. One to `C-2` and one to `C-3`. `A` correct but less used name is `3,4` diydro `-2H-`pyran. The oxa name is `1-`oxacyclohex`-1-`ene.