Photochemical Rearrangement of Oxaziridines and Nitrones in the Hexahydroindole Series: A Convenient Synthetic Route to 1-Azabicyclo[5.2.0]nonan-2-ones as Novel RGD Mimetics

Abstract

[reaction: see text] Photolysis of oxaziridines a or nitrones b provides a convenient synthetic route to fused bicyclic lactams c adequately substituted on both cycles A and B as scaffolds for mimicking conformationally constrained beta-turn peptides as in the tripeptide RGD signaling motif of fibronectin.

Six new monoterpenoid indole alkaloids from the aerial part of Gelsemium elegans

“…It is noteworthy that gelselenidine (1) is the first example of gelsedine-type alkaloid bearing a 2,3-epoxybutane residue, which represents a rare class of Gelsemium alkaloids with an additional C 2 unit. 10 The molecular formula of 2 was established as C 19 13 C NMR and DEPT spectra of 2 displayed 19 signals, including two methyls, four methylenes, eight methines, one carbonyl, and four quaternary carbons, suggesting the presence of a monoterpenoid indole alkaloid. Comparison of the NMR data of 2 with those of gelsedine 6 revealed that their chemical shifts were similar, except for the absence of signals for H-20 and the presence of an oxygenated quaternary carbon signal at d C 93.4 ppm, indicating an oxygen atom was attached to C-20.…”

“…9 Addition with acetaldehyde 10 and subsequent oxidation of the olefinic bond would afford gelselenidine (1). On the other hand, after oxidation of the imine N 4 /C-20 19 of 8, gelseziridine (2) could be yielded. Compound 2 might be a biogenetic precursor of 18,19-nor-gelsedinetype alkaloids, such as gelsedilam, 15 which is characterized by the oxaziridine cleavage and b-scission.…”

Synthesis of Three‐Membered and Four‐Membered Heterocycles with the Assistance of Photochemical Reactions

“…The photolysis of nitrones afforded bicyclic lactams as an instance to demonstrate the synthetic utility of photochemical rearrangement (Scheme 35) [78,140].…”

Computational Prediction of One-Step Synthesis of Seven-membered Fused Rings by (5+2) Cycloaddition Utilising Cycloalkenes

“…The construction of seven-membered fused rings has been an important issue in the synthesis of natural products and the development of new medicines 1 . Generally, these bicyclic compounds can be constructed through ring closure of monocyclic compounds 2 3 , rearrangement reactions 4 5 6 7 , intramolecular cycloaddition of five-carbon synthons bearing a tethered alkyne 8 9 10 11 12 or modification of previously formed seven-membered rings 13 . However, these methods typically require complicated reactants with subtly positioned functional groups, a substantial amount of organic solvents, and a lengthy course or several synthesis and separation steps.…”