Semisynthetic Studies Establish a Role for Conjugate Halide Exchange in the Formation of Chlorinated Pyrroloiminoquinones and Related Alkaloids.

Two novel pyrroloiminoquinone alkaloids, 6-chlorodamirone A and 6-bromodamirone A, have been identified for the first time from the marine sponge sp. (order: Poecilosclerida: family Latrunculiidae), sourced from Western Australia. Alongside these new compounds, seven previously known metabolites were also isolated.

Unified Divergent Total Synthesis of Discorhabdin B, H, K, and Aleutianamine via the Late-Stage Oxidative -Acetal Formation.

This study achieved the total syntheses of (+)-discorhabdin B, (-)-discorhabdin H, (+)-discorhabdin K, and (-)-aleutianamine. A phenethylamine fragment bearing a -pivaloylthio group, corresponding to the D/E/G ring moiety, was prepared from benzothiophen-2-carboxylic acid methyl ester and condensed with a known pyrroloiminoquinone derivative. The adduct was subjected to [bis(trifluoroacetoxy)iodo]benzene (PIFA)-promoted oxidative spirocyclization to furnish the A/B/C/D/E spirocyclohexadienone fused with pyrroloiminoquinone.

Cyclic Sulfamidite as Simultaneous Protecting Group for Amino Alcohols: Development of a Mild Deprotection Protocol Using Thiophenol.

This study describes the novel utility of cyclic sulfamidite as a simultaneous protecting group for 1,2- or 1,3-amino alcohols. An exceptionally mild and neutral condition for the removal of the cyclic sulfamidite was developed. The deprotection condition demonstrated a broad range of functional-group compatibility, including a substrate bearing a Z-enyne structure without any loss of double-bond stereochemistry.

Total Synthesis of (-)-Lepadiformine A via Radical Translocation-Cyclization Reaction.

Total synthesis of (-)-lepadiformine A featuring construction of the 1-azaspiro[4.5]decane skeleton by a highly diastereoselective radical translocation-cyclization reaction of a γ-lactam derivative bearing a chiral butenolide moiety is described. The enantioselective construction of butenolide is conducted via Krische's catalytic asymmetric allylation protocol.