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

Abstract

A review of the isolation, reported methods for the synthesis (up to the end of 2018), and spectroscopic data of angustureine, cuspareine, galipinine, and galipeine, members of the Hancock family of alkaloids based upon a 2‐substituted N(1)‐methyl‐1,2–3,4‐tetrahydroisolquinoline scaffold, is presented.

Mesoionic N-heterocyclic olefin catalysed reductive functionalization of CO2 for consecutive N-methylation of amines

“…We have tried selective N -monomethylation of primary amines by lowering the amount of 9-BBN and altering the reaction conditions; however, these attempts were not successful (see the ESI, Scheme S19 ‡ ). Furthermore, the current catalytic protocol was applied to synthesize two commercially available drug molecules such as angustureine 38,39 ( 7 ), an anti-malarial drug ( Scheme 5a ), and pempidine 17 ( 9 ), a ganglion-blocking drug ( Scheme 5b ), with 84% and 72% yields, respectively. Although compound 9 was synthesized earlier 17 by reductive functionalization of CO 2 , this is the first report of the synthesis of 7 using CO 2 as a reagent.…”

Metal‐Free Synthesis of Alkenylazaarenes and 2‐Aminoquinolines through Base‐Mediated Aerobic Oxidative Dehydrogenation of Benzyl Alcohols

“…It is highlighted that 3 ap is the starting material for preparing antimalarial natural compound (�)-Galipinine. [16] The reaction of (1-naphthyl)methanol 2 u also smoothly gave the product 3 au in 76 % yield. Amongst the heterocyclic methanols investigated during the study, (thiophene-2-yl)methanol 2 v and (pyridine-3yl)methanol 2 x gave the respective product 3 av and 3 ax, whereas alcohols 2 w and 2 y were found to be unsuited.…”

Synthesis of Tetrahydroquinolines via Borrowing Hydrogen Methodology Using a Manganese PN3 Pincer Catalyst

“…Aliphatic alcohols provided moderate to good conversions in general, providing a facile and atom-efficient access to norangustureine ( 3k ), a precursor of the important Hancock alkaloid (±)-angustureine. 28 For products 3i – 3k , the corresponding regioisomers were detected as minor products in diminishing amounts with increasing chain length. A higher catalyst loading was required for the sterically more demanding aliphatic alcohol 3-methylbutan-2-ol to obtain a satisfactory yield of 3l .…”

“…A significant decrease in yield was observed when higher substituted alcohols were applied ( 3e – 3g ). Aliphatic alcohols provided moderate to good conversions in general, providing a facile and atom-efficient access to norangustureine ( 3k ), a precursor of the important Hancock alkaloid (±)-angustureine . For products 3i – 3k , the corresponding regioisomers were detected as minor products in diminishing amounts with increasing chain length.…”