4-addition of the lithiated sulfones 5 and 6. The cyclisation of Z-sulfone 1 has been used for the isolation of the isomeric E-sulfone 2 from mixtures of 1 and 2. The lithiated sulfones 4–6 are chlorinated with hexachloroethane (HCE). Due to acid/base reactions the α,α-dichlorinated cyclic sulfone 23 and α,α'-dichlorinated butadienyl sulfones 13–15 are formed in small amounts.
在-78°下用
二异丙基氨基
锂(
LDA)
锂化1-3中的砜1–3具有区域选择性,因为α-
锂砜4的
氘化会导致α-单
十二烷基砜7的形成。较高的温度会导致分子内1,4-
锂化砜-addition 4到
锂化环状砜19和分子间1,4-加成
锂化砜的5和6。Z-砜1的环化已用于从1和1的混合物中分离异构体E-砜22。
锂化的砜4-6用
六氯乙烷(HCE)进行了
氯化。由于酸/碱反应,少量形成了α,α-二
氯环砜23和α,α'-二
氯丁二烯砜13-15。