I'm wondering if any reaction pathway exists (not involving enzymes) to do the following in aqueous solvent at temperatures < ~100°C:
To clarify, it's important however that the reaction is concerted, and that the W - X and Y - Z bonds are not broken until both the W-Y and X-Z bonds are formed. Bonds here must be covalent, but otherwise can be of any type. Any kind of catalyst can be used. Of course, it would be nice to know of an efficient reaction with minimally exotic conditions or reagents (i.e. it would be nice to avoid heavy metals for oxidative-addition type reactions), but I won't push my luck.
Does something like this exist?