Toward the synthesis of incargranine B and seneciobipyrrolidine. Synthesis of octahydro‐dipyrroloquinoline skeleton via dipolar cycloaddition/amination sequence

Abstract

Octahydro‐dipyrroloquinoline skeleton is the building component of a very few naturally occurring compounds. Nevertheless, these natural products have been attractive synthetic targets, and their study commanded development of efficient synthesis of this core. While the reported methods are based on the dimerization procedure of N‐arylpyrrolidines of N‐arylhomopropargyl amines, our approach relay on dipolar cycloaddition/amination sequence. This strategic approach allows sequential introduction of aromatic moieties increasing the product diversity and hence may be useful in further exploration of incargranine B or seneciobipyrrolidine derivatives.

C(sp3)–H cyclizations of 2-(2-vinyl)phenoxy-tert-anilines

“…55,56 For preparing the octahydro-dipyrroloquinoline skeleton several strategies were suggested in the literature, as (i) a chiral metal-phosphate-catalyzed asymmetric tandem hydroamination/formal Povarov reaction of aminoalkynes, 57 (ii) a domino Mannich/electrophilic aromatic substitution sequence of aniline derivatives, 58 (iii) oxidative annulation of aryl amines 59 or a (iv) cycloaddition/arylation sequence of azomethine ylides. 60 The operationally simple dimerization observed for 14b and 14h could serve as an interesting addition to this synthetic toolbox.…”

Ronald Ernest Grigg. 1 September 1935—10 January 2021

“…A related case involving a palladium(0)-catalysed carbonylation was the initial reaction of azomethine ylide precursors 58 and 59 with dipolarophile 55 to give intermediate 60 , which then proceeded to the final product 61 (25). The Grigg legacy of combining such different strands of organic chemistry continues in the hands of his co-workers (Hamill et al 2019; Simic et al 2021) as well as those of others (Ma et al 2020).…”

Palladium‐Catalyzed Cascade Cyclization for the Synthesis of Fused Benzo‐Aza‐Oxa‐[5‐6‐5] Tetracycles

“…The preferential formation of 3 f, supports the aforementioned aminopalladation procedure, because electron-rich amines are more favorable for this nucleophilic attack. [21] Finally, when H 2 18 O was added, the reaction afforded 3 a in 57 % yield (Scheme 4L), demonstrating that the γ-lactone of the product was entirely generated from cyclization of 3-butenoic acid.…”