Scheme 2. Synthesis of Hetidine Skeleton 27 and Attempted Conversion to Hetisine Skeleton (30).

Reagents and conditions: (a) PIDA (4 equiv), I₂ (5 equiv), DCE, 90-W sunlamp, 35 °C, 1 h (58–71%); (b) allylamine (5 equiv), MeOH, 60 °C, 12 h (78%); (c) LiAlH₄ (4 equiv), ether, 0 °C, 1 h (62%); (d) Ph₂S₂ (1.5 equiv), AIBN (0.2 equiv), benzene, 80 °C, 2 h (78%); (e) NaOCl (5 equiv), CH₂Cl₂, 0 °C, 30 min (55%). PIDA = phenyliodine diacetate, DCE = 1,2-dichloroethane, THF = tetrahydrofuran, AIBN = azobis(isobutyronitrile), TFA = trifluoroacetic acid.