Internal Nucleophilic Catalyst Mediated Cyclisation/Ring Expansion Cascades for the Synthesis of Medium‐Sized Lactones and Lactams

Abstract

Astrategy for the synthesis of medium-sized lactones and lactams from linear precursors is described in whicha n amine acts as an internal nucleophilic catalyst to facilitate an ovel cyclisation/ring expansion cascade sequence.T his method obviates the need for the high-dilution conditions usually associated with medium-ring cyclisation protocols,a s the reactions operate exclusively via kinetically favourable "normal"-sized cyclic transition states.T his same feature also enables biaryl-containing medium-sized rings to be prepared with complete atroposelectivity by point-to-axial chirality transfer.

A Thiol-Mediated Three-Step Ring Expansion Cascade for the Conversion of Indoles into Functionalized Quinolines

“…Cascade reactions (chemical processes by which two or more consecutive reactions take place in a single pot-process, also known as “tandem” or “domino” reactions) have wide utility in synthetic chemistry. 1 , 2 Incorporating cascade reaction sequences into synthetic routes can significantly improve the speed and ease with which complex target molecules can be prepared and often means that the direct handling of reactive, unstable and/or toxic species can be avoided by forming these intermediates in situ.…”