Construction of pyrrolophenanthridinone scaffolds mediated by samarium(II) diiodide and access to natural product synthesis

Formation of 8‐Hydroxyphenanthridines by Microwave‐Mediated IMDAF Reactions; Synthesis Directed towards Lycorine Alkaloids

“…for C 15 H 13 N [M] + 207.1048, found 207.1042. Spectral data were in good agreement with those reported before …”

“…In contrast to indoles where competing allylation at C‐3 can be a problem, N‐allylation of the indoline 19 proceeded smoothly and the allylindoline 20 was subjected to microwave‐mediated one‐pot cyclization/aromatization to give the target compound 21 . This tetracyclic compound has previously only been synthesized in very low yields by a SmI 2 mediated reductive cyclization . Anhydrolycorine (Figure ) has been oxidized to anhydrolycorinium chloride (Figure ) by treatment with air in the presence of acid .…”

“…The combined organic extracts were dried (MgSO 4 ) and concentrated in vacuo to give 21 (70 mg, 77 %) as a colorless solid, m.p. 71–73°C (Lit . 73–75°C).…”

Amaryllidaceae and Sceletium alkaloids

“…104 In addition, the tetracyclic core of pyrrolophenanthridone skeleton can also be readily constructed via an intramolecular Heck/oxidation cascade reaction, 105 or a samarium(II) diiodidemediated reductive cyclization process of aryl radicals. 106 2.3.3 Galanthamine-type alkaloids. An asymmetric total synthesis of (À)-galanthamine 69 and (À)-lycoramine 144 has A novel approach involving Rh(I)-catalyzed [(3 + 2) + 1] cycloaddition of 1-ene-vinylcyclopropane 151 with CO to form the cis-hydrodibenzofuran skeleton 152 has been described (Scheme 12).…”

Microwave assisted synthesis of phenanthridinones and dihydrophenanthridines by vasicine/KOtBu promoted intramolecular C–H arylation

“…19 Recently, Yamashita et al carried out the synthesis of pyrrolophenanthridinone derivatives by samarium(II)-iodide mediated reductive cyclization. 20 Even though successful methodologies are available, the use of aryl chlorides and aryl bromides as substrates in transition metalfree coupling is limited and is still in demand. Aryl chlorides are generally less reactive as compared to aryl bromides and aryl iodides.…”