Search files in windows .bat

I am looking for a way to list some files with a specific extension, in a specific subfolder, that is:

Directorios: 
a>a1>a2
b>b1>b2

Siendo b   Carpeta
   |  
   |b1  Sub Carpeta
   - |
     |
     |b2 Sub
     -

I want to list all the *.txt that are in the folder that contains "1".

I am doing it with:

for /R C:\ /D %%v in (*1*) do (
   echo %%v
)

So I get the directories, and so I look for the files

for /R "C:\" %%f in (*txt) do (
                echo "%%f"
)

Of course the last one looks for the *txt of all the directories.

I have tried to do:

for /R C:\ /D %%v in (*1*) do (

   for /R %%v %%f in (*txt) do (
                echo "%%f"
   )
)

What I was trying to do was pass the path of %%v to be the file search.

I suppose there will be some expression to be able to do this.