a BNF grammer for C# v2 has moved from www.devincook.com/GOLDParser/grammars/index.htm to goldparser.org/grammars.
It is mostly complete, and a good learning experience to both BNF and the C# syntax.
ANTLR grammers are available for C# 2, and a partially for C# 4.
–jeroen
via: c# 4.0 – C# grammar in BNF or EBNF Parser generator for F# – Stack Overflow.