Herein, we report the preparation of 1,2,4-thiadiazinane 1,1-dioxides from reaction of b-aminoethane sulfonamides with dichloromethane, dibromomethane and formaldehyde as methylene donors. The baminoethane sulfonamides were obtained through sequential Michael addition of amines to a,bunsaturated ethenesulfonyl fluorides followed by further DBU mediated sulfur(VI) fluoride exchange (SuFEx) reaction with amines at the S-F bond.Scheme 3 Formation of 1,2,4-thiadiazinane 1,1-dioxides under onepot conditions in DCM or using a two-step procedure with other methylene donors for cyclization. a (One pot) 10 equiv. amine, 50 mol% DBU, 5.0 ml DCM, reflux; b b-aminoethane sulfonamide, 20 mol% DBU, 5 ml DCM, reflux; c b-aminoethane sulfonamide, cat. acetic acid, 1.1 equiv. CH 2 O, 3 ml EtOH or MeOH microwave 90 C, 200 W, 5 min; d baminoethane sulfonamide, 20 mol% DBU, 5 ml DBM, reflux. Note for b-d, the yield refers to the final step.This journal is

C8H6BrFO2S, monoclinic, P21/m (no. 11), a = 4.7846(2) Å, b = 9.6099(4) Å, c = 10.3260(4) Å, β = 103.137(1)°, V = 462.36(3) Å3, Z = 2, Rgt(F) = 0.0193, wRref(F2) = 0.0502, T = 100(2) K.