Recent progress in the chemistry of indole alkaloids and mould metabolites

Abstract

GeneralSimple Alkaloids Non-tryptamines Non-isoprenoid Tryptamines Isoprenoid Tryptamine and Tryptophan Derivatives Ergot Alkaloids Monoterpenoid Alkaloids Aristotelia Alkaloids Corynan theine-Hetero yo himbine-Y o himbine Group, and Related Oxindoles Sarpagine-Ajmaline-Picraline Group Strychnine Group Ellipticine-Uleine-Apparicine Group Aspidospermine-Vincamine Group Catharanthine-Ibogamine Group Bisindole Alkaloids Biogenetically Related Quinoline Alkaloids Cinchona Group Camptothecin References* Very recently, 8 b Wyler has refuted this claim on the grounds that neobetanin is frequently found in aged solid betanin samples, but has never been isolated from fresh beet juice. Wyler is therefore of the opinion that neobetanin is an artefact, formed during the isolation process. NATURAL PRODUCT REPORTS, 1987 3 -(0 -Epoxy -0di hyd r o f a r n e s y I ) i ndole (23 1 Me R' * Note that the structure (33b) and the physical properties quoted in ref. 47a are those of perlolyrine, but it is incorrectly named perlolidine.* For a recent synthesis of ( + )-cinchonamine see Scheme 2 I ,

Cascades to Substituted Indoles

“…Having demonstrated the utility of the 3-ethylmethanethiol group in couplings with electrophiles, we targeted intramolecular Mannich-type (Pictet−Spengler) cyclizations of aminomalonate adduct 29 . Not only would these experiments demonstrate the utility of the 2-thiol group but if successful they would result in the formation of C-3 spiro compounds as are present in a number of bioactive indole natural products including, but not limited to, the spiroindolinone spirotryprostatin. , Exposure of 29 to 4 Å MS and propionaldehyde or acetaldehyde at room-temperature resulted in the formation of diastereomeric spirothioimidates 39 in high yields (Table ). These conditions are milder than the “normal” Pictet−Spengler conditions to β-carbolines where elevated temperatures are generally required…”

Novel [1,5] Sigmatropic Rearrangements of Cyclohexadienones Generated from Fischer Carbene Complexes. A New Strategy for Installing the C-20 Angular Ethyl Group in Aspidospermidine Alkaloids

“…Our approach 5 to the synthesis of the pentacyclic Aspidosperma indole alkaloid, vindoline 7 , involves the cyclohexadienone annulation 7 of the 1,3-disubstituted-indol-2-yl carbene complex 5 with alkyne 4 to yield the 4a-substituted carbazol-4-one 6 . These compounds were anticipated to furnish the required pentacyclic skeleton via a double intramolecular reductive amination (Scheme ).…”