Beilstein J. Org. Chem.2021,17, 2348–2376, doi:10.3762/bjoc.17.153
-amino alcohol 38 leading to the formation of (1R,2R,6R)-9-benzyl-9-azabicyclo[4.2.1]nonan-2-ol (39). The bicyclic derivative 39 through the number of consequent reactions formed a highly potent (+)/(−)-pyrido[3,4-b]homotropane (40), a bridged nicotinoid (Scheme 15) [61].
Similarly, precursor 41 at room
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Graphical Abstract
Scheme 1:
Schematic representation of Hg(II)-mediated addition to an unsaturated bond.
Beilstein J. Org. Chem.2021,17, 28–41, doi:10.3762/bjoc.17.4
), isolated from the Colorado blue spruce Picea pungens, are members of this alkaloid family. Their unique bicyclic system with a quaternary stereocenter, and the potent biological activity exerted by these homotropane alkaloids, make them attractive synthetic targets. This work aims briefly to review the
chemical ecology of Adalia bipunctata and the recent methodologies to obtain adaline (1), euphococcinine (2), and N-methyleuphococcinine (3).
Keywords: 9-azabicyclo[3.3.1]nonane; Coccinelid beetles; dipolar cycloaddition; homotropane; ring-closing metathesis; Introduction
Coccinellid beetles contain a
nature, but not less important. They possess biological properties, such as nicotinic acetylcholine receptor (nAChR) ligand [10][11], CNS (central nervous system) activity [12][13], and chemical defense [14][15][16]. Structurally, homotropane alkaloids have different skeletons including [3.3.1], [4.2.1