Heterosubstituted Chlorohydrins: Knoevenagel Reaction versus Epoxide Formation

Lithiated chloromethyl derivatives 2a-d, available by deprotonation of 2-(chloromethyl)1,3-benzothiazole 1a, -1,3-oxazoline 1b, -pyridine 1c and - quinoline 1d, react with carbonyl compounds to give chlorohydrins 3a-g and then epoxides 4a-g upon treatment with NaOH/PrOH. The same chlorohydrins 3a- g could be converted into heterosubstituted chloroalkenes 5a-g with very high E stereoselection upon reaction with MeSO 2Cl/Et 3N