Cook mix and stir thermodynamic synthesis
Pretty much all of today's natural chemistry and human performed chemistry.
The complement to mechanosynthesis / mechanochemistry and in particular force applying mechanosynthesis
which allows to access structures that are strongly metastable but are hard or not at all reachable via other means.
Including checkerboard compounds here aka neo-polymorphs, See: Pseudo phase diagram.
Side-note: Point is not to access almost all structures permittable by physical law
(most of them are not just metastable but also not very metastable at that)
but point is to access just a few (these are still many) novel ones as the basis for mechanical metamatwerials.
As for "cook mix and stir thermodynamic synthesis", it is what humans are doing mostly so far (2025).
Chemistry happening in the wild (geologic processes, life processes, and in outer space processes)
makes for the subset of natural chemistry which to good part overlaps with human.
There are notable exceptions of non-overlap both ways of course.
So unnatural chemistry mostly covers mechanosynthesis and
maybe some other exotic processes that for some reasons or others can't happen in nature.