Enantioselective Synthesis of 2-Carboxy Cyclic Ethers

Crown Ethers in Enantioselective Synthesis

A number of new chiral crown compounds and lariat ethers have been synthesized starting from phenyl-D-glucopyranoside, methyl-D-glucopyranoside and galactopyranoside, methyl-D-mannopyranoside and 1,2:5,6-di-O-isopropylidene-D-mannitol, but the main emphasis was laid on their application. Some of the sugar-based macrocycles showed significant asymmetric induction as phase transfer catalysts in l...

Enantioselective synthesis of hindered cyclic dialkyl ethers via catalytic oxa-Michael/Michael desymmetrization.

An asymmetric oxa-Michael/Michael cascade reaction of p-quinols and α,β-unsaturated aldehydes provides access to hindered dialkyl ethers. A highly enantioselective oxa-Michael addition of a tertiary alcohol precedes an intramolecular cyclohexadienone desymmetrization, which allows for the concomitant formation of four contiguous stereocenters in a single step. The highly functionalized bicyclic...

Synthesis of Cyclic Ethers via Lewis Acid Mediated

Pd-Catalyzed kinetic resolution of cyclic enol ethers. An enantioselective route to functionalised pyrans.

Functionalised cyclic enol ethers can be recovered with high levels of enantiocontrol after an asymmetric catalytic [1,3]-rearrangement reaction. These compounds can be further elaborated to a series of carbo- and heterocyclic products in good yield and with excellent levels of stereocontrol.

Enantioselective synthesis of cyclic sulfamidates via Pd-catalyzed hydrogenation.

Using Pd(CF3CO2) 2/(S,S)-f-binaphane as the catalyst, an efficient enantioselective synthesis of cyclic sulfamidates was developed via asymmetric hydrogenation of the corresponding cyclic imines in 2,2,2-trifluoroethanol at room temperature with high enantioselectivities (up to 99% ee).