Scheme 2. Synthesis of Thioethanamine and Sulfinylethanamine Analogues of (±)-1.

Reagents and conditions: (a) cysteamine hydrochloride, BF₃·OEt₂, glacial AcOH, 80–90 °C, ∼20 min (40–50 min for substituted analogues (procedure D)); (b) (i) procedure D; (ii) cyclopropane carboxaldehyde, NaBH₃CN, MeOH, 1,2-dichloroethane, room temperature, overnight; (c) (i) procedure D; (ii) BuBr, CsOH·H₂O, 4 Å MS, DMF, room temperature, 20 h; (d) LiAlH₄, H₂SO₄, THF; (e) BH₃·THF, THF, reflux, overnight; (f) NaIO₄, H₂O, EtOH, 0 °C to room temperature, overnight; (g) H₂O₂ (30%), AcOH–MeOH (1:3), 40 °C, 24 h.