Stetter reaction cascade

Another interesting process which falls within this category is a cascade Stetter-reaction Aldol process developed by Ye and co-workers [56]. In this reaction, phtha-laldehyde 171 was reacted with an achiral (V-heterocyclic carbene (NHC) 172. 

Chiral azolium salts 52 and 53 have been used in the intramolecular vinylogous Stetter reaction of oxygen substrates 54 to provide 3-substituted chromanones (Scheme 77) (13CEJ15852). Other examples are obtained from the free-radical cascade reaction of O-allyl acylphosphonate with various functionalized P-ketoxanthates in the presence of dilauroyl peroxide, with moderate to good yields (130L4818). A series of 2,3-disubstituted chromanones are synthesized from the reaction of acrylic acids with arynes in the presence of CsF (13T2789). 

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