Stereoselective Sequential Spirocyclopropanation/Cloke–Wilson Rearrangement Reactions for Synthesis of <i>trans</i>-β,γ-Disubstituted γ-Butyrolactones Using Alkylidene Meldrum’s Acid and Benzyl Halides
spirocyclopropanation/Cloke-Wilson rearrangement reactions have been developed to synthesize γ-butyrolactones using alkylidene Meldrum's acids and benzyl halides. The DBU-promoted spirocyclopropanation was carried out efficiently at room temperature to generate trans-isomeric spirocyclopropyl Meldrum's acid, and the following stereospecific thermal decarboxylative Cloke-Wilson rearrangement afforded trans-γ-butyrolactones
bifunctional thiourea–tertiary amine as catalyst, domino Michael-type Friedel–Crafts alkylation/cyclization of β-naphthols with akylidene Meldrum’s acids was realized. The reactions afforded various enantioenriched β-arylsplitomicins with good yields (up to 99%) in moderate enantioselectivities (up to 79%).