unable to match grep pattern

Hi All,
I am trying to select all files in a directory which are not with .gz extension .
for which I am using below script ,
but its rejecting both .gz and .z extension files,as in [] each letter is considered separately.

PFB

ls -lrt | awk '{print $9}'| egrep "^IRAMS.*[^gz]$"

please suggest a script to select all files without .gz extension

Try:

ls -rt | grep -v '\.gz$'