ChemInform Abstract: Silicon‐Directed Nazarov Cyclizations. Part 5. Substituent and Heteroatom Effects on the Reaction.

Abstract

A series of divinyl ketones such as (IV) is synthesized by one of the methods exemplified in the scheme by the reactions a) (I) + (II) → (IIIa) → (IVa), b) (V) + (VI) → (IIIb) → (IVb), and c) (VII) + (VIII) → (IIIe) → (IVe).

Theoretical Studies on Pentadienyl Cation Electrocyclizations

“…The addition of electron-donating groups to C1, C3 or C5 should, in principle, impart stabilization to the acyclic cation, perhaps facilitating its generation from neutral precursors, but this stabilization would be [14]. lost as the cyclization proceeds, resulting in an increase in activation energy [19]. [12].…”