Convergent Access to Polycyclic Cyclopentanoids from α,β-Unsaturated Acid Chlorides and Alkynes through a Reductive Coupling, Nazarov Cyclization Sequence

Reductive
coupling of α,β-unsaturated acid chlorides A with alkynoyls B provides convergent access
to Nazarov cyclization precursors, α-carboxy divinyl ketones C. Cyclization of C gives an intermediate oxyallyl
cation intermediate D, which can be trapped with tethered
arenes (Ar). The resultant products can be further cyclized through
nucleophilic displacement of suitable leaving groups X by tethered
OH groups to give lactones (in a subsequent step). Where X is a suitable
chiral auxiliary (e.g., oxazolidinone) this strategy affords access
to homochiral cyclopentanoids.