So my friend don't have portal 1, and I want him to decompile some portal prelude maps.

Well the problem is he said he needs portal 1 so the bsp source can read content or something else. Is that true? Because I want him to decompile some maps for me and I don't know if it will work.

As I know, for BSPSOURCE or any decompile prog, you don't need any game installed, because it only uses and extracts/decompiles the contents from the BSP. The map information, triggers, brushes etc, and some extractor can export embedded content (custom textures, scripts, models etc.)
They don't even ask where portal1 or 2 located.
So he can extract the .VMF for you or you can just ask to pack and send the bsps to you and you can extract them (up to 100MB sharing you can use wikisend.org no registration needed, just ask him to upload BSPs in zip and share the link). or you can even share the link with me and I can decompile and send the VMF if you still have problem starting bspsource or extracting the maps.

Thank you here are the links https://www.dropbox.com/sh/jy7sxbyln36s ... HWuNa?dl=0 (couldn't find the guy on my steam >.> I have a lot of friends)