A Maitland-Japp inspired synthesis of dihydropyran-4-ones and their stereoselective conversion to functionalised tetrahydropyran-4-onesElectronic supplementary information (ESI) available: General experimental procedures and copies of spectroscopic data. See DOI: 10.1039/c5ob00292c

The Maitland-Japp reaction has been extended to the synthesis of highly functionalised dihydropyran-4-ones. These dihydropyran-4-ones can in turn be converted stereoselectively into tetrahydropyran-4-ones with tertiary and quaternary stereocentres via the one-pot addition of hydride or carbon nucleophiles and trapping with carbon electrophiles. The utility of this method is demonstrated by providing access to the functionalised tetrahydropyran units present in a component of the Civet fragrance and the anticancer polyketide lasonolide A. New variations of the Maitland-Japp reaction have been developed to enable the synthesis of dihydropyrans and tetrahydropyrans with tertiary and quaternary stereocentres, including the functionalised tetrahydropyrans in Civet and the A-ring of lasonolide A.