Amide-assisted intramolecular [3+2] annulation of cyclopropane ring-opening: a facile and diastereoselective access to the tricyclic core of (±)-scandine

Abstract

The highly diastereoselective intramolecular [3+2] annulation via the ring-opening of a cyclopropane diester derivative has been developed to construct a dihydroquinolinone scaffold. A series of tricyclic dihydroquinolinones bearing one or two all-carbon quaternary stereogenic centers were obtained in good yields and excellent diastereoselectivities (up to 20 : 1 dr). Moreover, the amide-linking mode shows obviously beneficial effects on the ring-opening of cyclopropane.

Donor–Acceptor Cyclopropanes as an Expedient Building Block Towards the Construction of Nitrogen‐Containing Molecules: An Update

“…devised a novel amide‐linked intramolecular [3+2] annulation via the ring opening of the donor–acceptor cyclopropane 1,1‐diester motif 138 . It gave rise to the synthesis of a series of tricyclic dihydroquinolinones 139 bearing one or two all‐carbon quaternary stereogenic centers in good yields (53–87%) with excellent diastereoselectivities (up to 20:1 dr ) (Scheme ) . The introduction of an amide as the linker significantly facilitated the annulation.…”

A Highly Enantio‐ and Diastereoselective Synthesis of Spirocyclic Dihydroquinolones via Domino Michael Addition‐Lactamization of ortho‐Quinone Methide Imines

“…For example, a Pd‐catalyzed C−H bond activation/C−C bond formation/cyclization cascade assembles the quinolone scaffold from simple anilines . A TiCl 4 ‐mediated ring‐opening strategy of cyclopropanes has been developed for the synthesis of complex tricyclic dihydroquinolones with excellent diastereoselectivity . Silver‐catalyzed radical 6‐ endo ‐ trig cyclizations of cinnamides furnish 3,4‐dihydroquinolin‐2(1 H )‐ones very effectively .…”

cis-Selective, Enantiospecific Addition of Donor–Acceptor Cyclopropanes to Activated Alkenes: An Iodination/Michael-Cyclization Cascade

“…Different approaches have been developed for the synthesis of the Melodinus alkaloid core . Two prominent strategies by Stoltz and Yang incorporate the use of D-A cyclopropanes. Our new method extends the synthetic possibilities of these approaches.…”

“…Melodinus alkaloids have been a prime target for the application of the formal all-carbon (3 + 2)-cycloaddition. Stoltz and Yang developed different approaches for the synthesis of the alkaloid’s core. , Stoltz refined Tsuji’s method for the addition of vinyl cyclopropanes to activated nitroalkenes. Yang developed an amide-linker assisted reaction that is promoted by Lewis acid activation.…”