Acylative kinetic resolution of alcohols using a recyclable polymer-supported isothiourea catalyst in batch and flow

The authors thank the EPSRC Centre for Doctoral Training in Critical Resource Catalysis (CRITICAT, grant code EP/L016419/1, R.M.N.P.) for funding. Financial support from the EPSRC (EP/K000411/1) is gratefully acknowledged (R.C.). The European Research Council under the European Union’s Seventh Framework Programme (FP7/2007-2013) ERC Grant Agreement No. 279850 is also acknowledged. A.D.S. thanks the Royal Society for a Wolfson Research Merit Award. C.R.-E. and M.A.P. acknowledge the financial support from CERCA Pro-gramme/Generalitat de Catalunya, MINECO (CTQ2015-69136-R, AEI/MINECO/FEDER, UE and Severo Ochoa Excellence Ac-creditation 2014–2018, SEV-2013-0319) and DEC Generalitat de Catalunya (Grant 2014SGR827).A polystyrene-supported isothiourea catalyst, based on the homogeneous catalyst HyperBTM, has been prepared and used for the acylative kinetic resolution of secondary alcohols. A wide range of alcohols, including benzylic, allylic and propargylic alcohols, cycloalkanol derivatives and a 1,2-diol, has been resolved using either propionic or isobutyric anhydride with good to excellent selectivity factors obtained (28 examples, s up to 622). The catalyst can be recovered and reused by a simple filtration and washing sequence, with no special precautions needed. The recyclability of the catalyst was demonstrated (15 cycles) with no significant loss in either activity or selectivity. The recyclable catalyst was also used for the sequential resolution of 10 different alcohols us-ing different anhydrides with no cross-contamination between cycles. Finally, successful application in a continuous flow process demonstrated the first example of an immobilized Lewis base catalyst used for the kinetic resolution of alcohols in flow.PostprintPeer reviewe

H‑Bond-Directing Organocatalyst for Enantioselective [4 + 2] Cycloadditions via Dienamine Catalysis

An efficient, highly regio- and stereoselective [4 + 2] cycloaddition reaction to generate tetrahydropyranopyrazole frameworks has been developed. To this end, a dienamine-based catalytic strategy that relies on the H-bond-directing effect of the hydroxy group of a dinaphthylprolinol-type aminocatalyst has been used. This enables the synthesis of multifunctionalized heterocyclic derivatives with three contiguous stereocenters in good yields and excellent enantioselectivities

Acylative kinetic resolution of alcohols using a recyclable polymer-supported isothiourea catalyst in batch and flow

A polystyrene-supported isothiourea catalyst, based on the homogeneous catalyst HyperBTM, has been prepared and used for the acylative kinetic resolution of secondary alcohols. A wide range of alcohols, including benzylic, allylic and propargylic alcohols, cycloalkanol derivatives and a 1,2-diol, has been resolved using either propionic or isobutyric anhydride with good to excellent selectivity factors obtained (28 examples, s up to 622). The catalyst can be recovered and reused by a simple filtration and washing sequence, with no special precautions needed. The recyclability of the catalyst was demonstrated (15 cycles) with no significant loss in either activity or selectivity. The recyclable catalyst was also used for the sequential resolution of 10 different alcohols us-ing different anhydrides with no cross-contamination between cycles. Finally, successful application in a continuous flow process demonstrated the first example of an immobilized Lewis base catalyst used for the kinetic resolution of alcohols in flow