Monofunctional Thio urea Hydrogen-bond Catalysis

2 Monofunctional Thio(urea) Hydrogen-bond Catalysis 

In 2006, Kleiner and Schreiner reported an environmentally friendly protocol for the synthesis of (3-amino alcohols utilising thiourea 8 under aqueous reaction conditions. Water acts synergistically, amplifying the reaction yield through hydrogen-bond formation. Propene oxide and cyclohexene oxide were used as substrates with a series of primary and secondary 

1 - 3 alcohols cyanohydrins a-hydroxy carbonyls aldols oximes 

In 2008, Connon and coworkers reported a base-mediated protocol for the S3mthesis of terminal epoxides from aldehydes and trimethylsulfonium iodide utilising 5 mol% of urea analogue 9. Electron-rich and electron-deficient aromatic aldehydes were well tolerated providing the corresponding products in moderate to high yields. In the case of cycloheigrl carboxaldehyde, an increase in the reaction time was required. It has to be 

Seheme 19.15 Asymmetric Mukaiyama-Mannich reaction catalysed by thiourea 11. 

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