Because indoline is an important intermediate of angiotensin‐converting enzyme (ACE) inhibitor and the antihypertensive drug “pentopril”, and also because it is a ubiquitous scaffold found in the structures of several naturally bioactive alkaloids such as vinblastine, strychnine, (–)‐physostigmine, ajmaline, and (+)‐aspidospermidine, the synthesis of this “privileged structure” is meaningful in the design of new biologically active medicines. This microreview describes the recent advances in the synthesis of indoline derivatives, including Cu‐ and Pd‐catalyzed reactions, metal‐free approaches (radical reaction), as well as other types of reactions.

Two alkaloids, oleraceins F and G, were isolated from Portulaca oleracea L., and their structures were determined as methyl (2S)-6- [(b-d-glucopyranosyl) [7], and alkaloids such as dopa, dopamine, noradrenaline, betalain, N-trans-feruloyltyramine, cyclodipeptide [8], etc.In our previous study, five alkaloids named oleraceins A -E were isolated from this plant [9], and some of them exhibited potent antioxidant activities [10]. Further screening for this kind of alkaloid in the EtOH extract of P. oleracea using LC/MS/MS has furnished two new analogs, whose molecular weights are higher than those of oleracein A or B [11], respectively, by 14. These two alkaloids were named oleraceins F (1) and G (2). Here, we describe the isolation, purification, structure elucidation of these two compounds, as well as their scavenging activity against the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical.

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