Highly Stereoselective Olefin Cyclopropanation of Diazooxindoles Catalyzed by a C₂-Symmetric Spiroketal Bisphosphine/Au(I) Complex

Abstract

A spiroketal bisphosphine (SKP) derived chiral digold complex is identified as a powerful catalyst for the highly diastereo- and enantioselective synthesis of spirocyclopropyloxindoles from diazooxindoles and a broad range of alkenes, including both cis and trans 1,2-disubstituted alkenes.

Nickel(ii)-catalyzed enantioselective cyclopropanation of 3-alkenyl-oxindoles with phenyliodonium ylide via free carbene

“…The asymmetric catalytic cyclopropanations of electron-deficient oxindolic olefins were generally realized with Michael-Initiated Ring-Closing sequence (MIRC) reaction 9. Moreover, olefin cyclopropanation with diazooxindoles via the carbene transfer could also give access to these targets 10. Based on our long-term endeavor in the development of chiral catalysts stemmed from metal/ N , N ′-dioxide complexes11 as well as our previous study of oxindole derivatives,12 we envision that a chiral Lewis acid catalyst of N , N ′-dioxide could bind 3-alkenyl-oxindoles into a perfect chiral environment, benefiting the cyclopropanation of a free carbene generated from spontaneous decomposition of phenyliodonium ylide malonate (Scheme 1b).…”

Mechanism and stereoselectivity of the Rh(ii)-catalyzed cyclopropanation of diazooxindole: a density functional theory study

“…[1][2][3][4] Therefore, spirocyclic oxindole scaffolds have continued to draw attention in recent years. [8][9][10][11][12] Since the pioneering work of Nozaki and Noyori, 13 the transition metal-catalyzed asymmetric cyclopropanation between diazo compounds and alkenes has emerged as a powerful strategy for the synthesis of cyclopropane derivatives. [5][6][7] As a result, great efforts have been directed toward asymmetric construction of these scaffolds.…”

Gold(I)-catalyzed enantioselective cycloaddition reactions

“…In particular, the authors demonstrated that the chiral bisgold complex Au6 , derived from the spiroketal bisphosphine ligand, was a very efficient promoter of the cyclopropanation between donor–acceptor diazooxindoles such as 9 and a broad range of alkenes (Scheme 6) [47]. The resulting spirocyclopropyloxindoles 10 , which are obtained in excellent yields and enantioselectivities, are appealing structures from a medicinal point of view.…”