Novel chiral biheteroaromatic diphosphine oxides for Lewis base activation of Lewis acids in enantioselective allylation and epoxide opening

Enantiomerically pure biheteroaromatic diphosphine oxides were synthesised and tested as organocatalysts in two different reactions involving trichlorosilyl compounds. The allylation of aldehydes with allyl(trichloro) silane afforded homoallylic alcohols in fair to good yields and up to 95% ee. Preliminary experiments showed that this new class of metal-free catalysts was able also to promote the stilbene oxide opening by addition of tetrachlorosilane with enantioselectivity higher than 80%. The interesting results in terms of chemical and stereochemical efficiency open the way to further studies towards the development of new chiral heteroaromatic Lewis bases as efficient metal-free catalysts.