The paper presents a systematic method for synthesizing asynchronous circuits from event-based specifications with conflicts on output signals. It describes a set of semantic-preserving transformations performed at the Petri net level, which introduce auxiliary signal transitions implemented by internally analogue components, Mutual Exclusion (ME) elements. The logic for primary outputs can therefore be realized free from hazards and external meta-stability. The technique draws upon the use of standard logic components and two-input MEs, available in a typical design library.