Asymmetric synthesis of 2-alkyl-substituted tetrahydroquinolines by an enantioselective aza-Michael reaction

The Hancock Alkaloids (−)-Cuspareine, (−)-Galipinine, (−)-Galipeine, and (−)-Angustureine: Asymmetric Syntheses and Corrected 1H and 13C NMR Data

“…25 Although Diaz-Munõz et al made no comment regarding the agreement of NMR spectroscopic data for galipeine and angustureine, we 26 simultaneously reported the results of our own, independent investigations into discrepancies that we had noted between the 1 H and 13 C NMR data reported by Jaquemond-Collet et al 10 for (−)-galipeine and the analogous data for purported synthetic samples thereof. 27,28 In fact, our study revealed that the originally proposed structure of this alkaloid was, unfortunately, erroneous and culminated in its structural revision; our study therefore also constitutes the first time (and to date the only time) 29 that a synthetic sample of this alkaloid has been prepared. 26 In this article, we delineate the full development of our approach to enable access to all of the members of this alkaloid family, which thus enabled preparation of (−)-cuspareine, (−)-galipinine, and (−)-angustureine, as well as (−)-galipeine.…”

The Hancock Alkaloids Angustureine, Cuspareine, Galipinine, and Galipeine: A Review of their Isolation, Synthesis, and Spectroscopic Data

“…Hii et al reported a catalytic asymmetric aza‐conjugate addition of aniline as the stereodefining step in syntheses of members of the Hancock alkaloid family. Swern oxidation of monoprotected diol 115 followed by olefination of the resultant aldehyde with ylide 116 gave the requisite α,β‐unsaturated carbonyl derivative 117 in 74 % yield.…”

Quinolines, Isoquinolines, Angustureine, and Congeneric Alkaloids — Occurrence, Chemistry, and Biological Activity

“…There is an excellent review of the chemistry and synthesis of 1,2,3,4-tetrahydroquinolines by Diaz and Dudley [56]. In 1999, Jacquemond-Collet and coworkers [57] isolated and characterized these four tetrahydroquinoline alkaloids (Figure 11) from the extract of the bark of Galipea officinalis, commonly known as "angostura" [58]. The genus Galipea comprises about 20 species that are found predominantly in the Northern of South America.…”