Described herein are crystalline forms of a compound of formula (IIΓ), including toluene solvates off A TD-CLE, as well as processes for the preparation thereof and use thereof in the preparation of cephalosporin compounds such as ceftolozane. Provided herein is a crystalline form of a compound of formula (IIΓ): wherein X is CI, Br, or I; and R1 and R2 are each independently an oxygen protecting group; processes for making the crystalline form, and use of said form in the synthesis of antibacterial cephalosporins such as ceftolozane.