Asymmetric organocatalytic Michael addition of cyclopentane-1,2-dione to alkylidene oxindole.

Estelle Silm,Ivar Järving,Tõnis Kanger

doi:10.3762/bjoc.18.18

Abstract

An asymmetric Michael reaction between cyclopentane-1,2-dione and alkylidene oxindole was studied in the presence of a multifunctional squaramide catalyst. Michael adducts were obtained in high enantioselectivities and in moderate diastereoselectivities.

Highlights

Diketones are generally very versatile starting materials in organic synthesis [1,2]
We focused on the screening of squaramides
When squaramide C was used as a catalyst, the product was isolated in 80%/87% ee (Table 1, entry 3)

Summary

Introduction

Diketones are generally very versatile starting materials in organic synthesis [1,2]. An asymmetric Michael reaction between cyclopentane-1,2-dione and alkylidene oxindole was studied in the presence of a multifunctional squaramide catalyst. Squaramide and thiourea catalysts were screened in a model reaction between CPD 1 and Boc-protected benzylidene oxindole 2a at room temperature in the presence of 10 mol % of catalyst (Figure 2).

Results

Conclusion