I'm looking for references on the structure which can be roughtly described as follows: given a (braided or symmetric) monoidal category $C$, I want to consider a simplicial set $N(\mathbf{B}C)$ with a single vertex, an edge for every object of $C$, a triangle with edges $X,Y,Z$ for every morphism $\varphi:Z\to X\otimes Y$, a tethraedron for every four triangles making up a commutative diagram involving the associator of $C$, higher coherences..