Gold-Catalyzed "Anti-Baldwin" Cyclization of Unactivated Alkenes

<jats:p>Owing to the unfavorable orbital alignments and geometric constraints, 5-endo-trig cyclizations are kinetically disfavored as stated by Sir Jack Baldwin. Consequently, reports of such cyclization are scarce and primarily rely on the use of activated alkenes. Herein, we report a rare example of "anti-Baldwin" cyclization of unactivated alkenes. The key to the success of this transformation is that the kinetically favored 4-exo-trig cyclization is reversible, thereby enabling equilibration to the thermodynamically favored 5-endo-trig cyclization intermediate which then undergoes reductive elimination to form the product.</jats:p>