Probably not, he had no reason to use them, especially when already winning, while the rebels knew that any use (real or not) of chemical weapons would give the US justifications for sanctions of other interventions, and every instance of supposed use of chemical weapons happenned in areas held by the rebels, or were “revealed” by the rebels-and-NATO-aligned white helmets, or similar suscpiscious contexts.
Probably not, he had no reason to use them, especially when already winning, while the rebels knew that any use (real or not) of chemical weapons would give the US justifications for sanctions of other interventions, and every instance of supposed use of chemical weapons happenned in areas held by the rebels, or were “revealed” by the rebels-and-NATO-aligned white helmets, or similar suscpiscious contexts.