A termolecular condensation reaction of harmane, alkyl halide, and dimethyl oxalate has been developed for the construction of a variety of canthin-5,6-diones. The carbon skeleton of amarastelline A, a fluorescent canthin alkaloid, was synthesized in 99.8% yield by applying this procedure.
KoikeK., YoshinoH., NikaidoT. (1999) Synthesis and antitumor activity of canthine-5,6-dione derivatives. Heterocycles, 51, 315–323.
3.
SasakiT., LiW., OhmotoT., KoikeK. (2016) Evaluation of canthinone alkaloids as cerebral protective agents. Bioorganic & Medicinal Chemistry Letters, 26, 4992–4995.
4.
YokooH., OhsakiA., KagechikaH., HiranoT. (2016) Structural development of canthin-5,6-dione moiety as a fluorescent dye and its application to novel fluorescent sensors. Tetrahedron, 72, 5872–5879.
5.
TaniguchiK., TakizawaS., HiranoT., MurataS., KagechikaH., KishidaA., OhsakiA. (2012) Amarastelline A: Fluorescent alkaloid from Quassia amara and its properties in living cells. ChemPlusChem, 77, 427–431.
6.
MatusI., FischerJ. (1985) An usually simple procedure for the synthesis of canthin-alkaloid derivatives using dialkyl oxalates as new regioselective N-alkylating agents. Tetrahedron Letters, 26, 385–388.
7.
Nikaido also reported similar procedure in 1999, see reference [2].
8.
ZhangL., ChangL., HuH., WangH., YaoZ.J., WangS. (2014) Azocinoindole synthesis by a gold(I)-catalyzed ring expansion of 2-propargyl-β-tetrahydrocarboline. Chemistry-A European Journal, 20, 2925–2932.
