Aqueous bio-compatible reducing agents are legion, but people end up using the same ones over and over. Probably the least used is TCEP (which doesn’t stink at all), next is dithiothreitol (and the related but slightly less effective dithioerythritol), which stinks, but not too badly. Perversely, biologists usually seem to end up using beta-mercaptoethanol, which is the stinkiest of the lot.
BME stinks, but not too badly – the burnt rubber smell has a pleasant organic alcohol note in the background, making it not such a miserable smell. Uninitiated coworkers might disagree.
Certain synthetic DNA bases require a mixture of concentrated ammonia + beta-mercaptoethanol to deprotect and cleave them from the support. Oh, and you heat them. Don’t spill, and work in the hood. I speak from bitter experience.