There really are no alternatives.
The compilers for .NET compile down to MSIL, Microsoft Intermediate Language. It's a processor agnosti bytecode that is "compiled" by the .NET CLR JIT Compiler into machine code specific to processor the CLR is running on. There are no alternatives.
The "alternative" to the compilers built into .NET is Roslyn - The .NET compiler platform
] which is open source.
There are alternative IDE's but they all use the compilers built into .NET and Roslyn to build the code.