Phosphine‐Catalyzed Enantioselective (3+2) Annulation of Vinylcyclopropanes with Imines for the Synthesis of Chiral Pyrrolidines

Abstract

A phosphine-catalyzed highly enantioselective and diastereoselective (up to 98 % ee and > 20 : 1 dr) (3+2) annulation between vinylcyclopropanes and Ntosylaldimines has been developed, which allows facile access to a range of highly functionalized chiral pyrrolidines. Notably, this method makes use of vinylcyclopropanes as a synthon for phosphine-mediated asymmetric annulation reaction, which will offer new opportunities for potential applications of cyclopropanes substrates in phosphine-catalyzed organic transformations.

Asymmetric cross Rauhut–Currier reactions of vinyl ketones with carbonylpara-quinone methidesviaphosphine catalysis

“…The phosphine-catalyzed Rauhut–Currier (R–C) reaction is a powerful method for constructing a carbon–carbon bond with the introduction of an extra functional α,β-unsaturated double bond (Scheme 2a). 8 Moreover, the development of an asymmetric R–C reaction can provide many possibilities in the realm of stereoselective C–C bond formation. 9 As an example, terminal aryl p -QMs were employed in R–C methodology under chiral phosphine catalysis; this was developed by the Zhang and Wu groups independently (Scheme 2b).…”

Synthetic and Computational Study of the Enantioselective [3+2]-Cycloaddition of Chromones with MBH Carbonates

“…The Morita–Baylis–Hillman (MBH) carbonate is a kind of diversified building block in organic synthesis. Notably, it has been widely employed in [1+ n ]- and [3+ n ]-cycloadditions of various electrophiles under Lewis base organocatalysis, showing many advantages such as being readily accessible and easy to handle, having great functional-group compatibility, and being highly efficient in transformations. To the best of our knowledge, catalytic reactions of chromones and MBH carbonates for access to chromanones have not been well investigated, likely due to the difficulties in controlling selectivity and low reactivity of chromone .…”

Phosphine-catalyzed activation of cyclopropenones: a versatile C3 synthon for (3+2) annulations with unsaturated electrophiles

“…In 2018, we disclosed that electron-deficient vinylcyclopropanes (VCPs) undergo phosphine-catalyzed activation to generate zwitterions A that triggers the rearrangement of vinylcyclopropylketones to cycloheptenones (Figure 1b, up). 7 Very recently, an elegant phosphine-catalyzed enantioselective (3+2) annulation of electron-deficient vinylcyclopropanes with Ntosylaldimines with a zwitterion B as the key intermediate has been developed by Lu and co-workers 8 (Figure 1b, down). In the meantime, we have established that electron-deficient alkylidenecyclopropanes (ACPs) also readily undergo phosphinecatalyzed substrate-controlled rearrangements to afford polysubstituted furans and dienones.…”

“…1b , up). 7 Very recently, an elegant phosphine-catalyzed enantioselective (3 + 2) annulation of electron-deficient vinylcyclopropanes with N -tosylaldimines with a zwitterion B as the key intermediate has been developed by Lu and co-workers 8 ( Fig. 1b , down).…”