Double [2, 3] sigmatropic rearrangements of bis (propargyl sulfenates) to bis (allenic sulfoxides) and of bis (propargyl sulfinates) to bis (allenic sulfones) are shown to be a convenient and effective method for the preparation of conjugated diallene systems bearing two electron withdrawing trihalomethyl sulfoxide or sulfone substituents either on C-1 and C- 6, or on C-3 and C-4. Such substituents are further shown to facilitate cyclization to bis ( ...