Something that provides syntactic sugar that compiles down to C? You'd be looking for Vala[1]. I haven't used it so I can't vouch for it in practice, but I know it compiles to C and uses the GObject system for object-oriented programming. It's not as much of a syntax change for C, but it apparently adds quite a bit semantically. There's also a Scheme implementation called Chicken[2] that compiles to C source, and I know there are others that I'm not recalling off the top of my head.

[1]: https://en.wikipedia.org/wiki/Vala_%28programming_language%2... [2]: https://en.wikipedia.org/wiki/Chicken_%28Scheme_implementati...