That's 3.3lbI will start at arounf 1.500 for frame and fork
You're out of retro territory.
Very small retro frames may get you to just over 3lb they're probably all 3.3lb or so.
That's Cadex, Light Alu 'dale etc
Hit the modern era early 00's and you get scandium to play with and lighter Alu frames too.
Perhaps 1997 staying retro...
gets you the Scott Endorphin which I think is sub 3lb is 15" type sizes.
Just need to find some 150-250g forks and you're in.