Synthesis of the Macrocyclic Spermidine Alkaloid (±)-(2R*,3R*)-3-Hydroxycelacinnine

Abstract

The macrocyclic lactam alkaloid (±)‐(2R*,3R*)‐3‐hydroxycelacinnine (1) derived from spermidine was synthesized via stereoselective epoxide‐ring opening with magnesium azide and cesium carbonate promoted macrocyclization of the ditosylated diamino precursor 12 with 1,4‐dibromobutane in the two key steps (Scheme 2). 1H‐ and 13C‐NMR Signal assignments from COSY, HSQC, and HMBC 2D NMR data of the synthesized 1 were compared with the earlier‐described data of the natural 3‐hydroxycelacinnine. The similarity of their 13C‐NMR spectra point to the correctness of the proposed constitutional formula for natural 3‐hydroxycelacinnine; however, different 1H‐NMR chemical shifts and coupling constants (J(2,3)=9.0 vs. 1.2 Hz, resp.) in the α‐hydroxy‐β‐amino lactam moiety suggest that natural 3‐hydroxycelacinnine is the 2,3‐cis‐epimer of one synthetic (±)‐1.

Heterogenisation of a C‐Scorpionate FeII Complex on Carbon Materials for Cyclohexane Oxidation with Hydrogen Peroxide

“…For this study we started with the reactions of epoxy amides 3a and 3l with NaN 3 in DMF at 70 °C or in MeOH at reflux, obtaining a 1:4 and 1:2 mixture of regioisomers 23a / 23b and 24a / 24b in combined yields of 86 and 68 %, respectively. The preference of the azide anion to react at the 3‐position in reactions with epoxy amides has already been reported by Sharpless and co‐workers,13 which was remarkably boosted by the use of Mg(N 3 ) 2 ,14 and which we observed for 3a and 3l (see Table 2). Our interest in the C‐2 ring‐opened products prompted us to study this reaction in more detail by screening a variety of different reaction conditions, as summarized in Table 2.…”

Photons or Electrons? A Critical Comparison of Electrochemistry and Photoredox Catalysis for Organic Synthesis

“…Horner and Neuman reported electrochemical conditions in 1965 relying on a Hg pool cathode. , Constant current electrolysis using a divided cell and a lead cathode was reported by Iwasaki and Matsumoto in 1973 . While the literature has numerous reports of related conditions utilizing a Hg pool cathode, − select examples using RVC exist which are more practical and greener alternatives (Scheme , methods A1, A2, and A3) . Silvestri reported constant potential electrolysis using a compact graphite cathode in a divided cell (Nafion 324 cation exchange membrane) in batch mode, as well as a related continuous batch recirculation mode using a filter press two-compartment microflow cell to effect detosylation of tetratosylcyclen to cyclen reaching as high as 80% yield with 55% faradaic efficiency .…”

Polyamine alkaloids

“…Electrolytic removal of the N-tosyl residue and acylation with cinnamoyl chloride gave finally the first target compound 18, which proved to be different from natural 3-hydroxycelacinnine. 59 Since the skeleton of the natural product appeared to be correctly assigned, the structure of 3-hydroxycelacinnine was supposed to correspond to the cis-configured isomer of 18.…”