Lewis Base-Switched [3 + 3] and [4 + 2] Annulation Reactions of δ-Acetoxy Allenoates with Cyclic N-Sulfonyl Imines: Divergent Synthesis of Functionalized α-Pyridyl Acetates and Teraryl Scaffolds

Sanjeeva K Arupula; Asif Ali Qureshi; K C Kumara Swamy

doi:10.1021/acs.joc.9b03281

Lewis Base-Switched [3 + 3] and [4 + 2] Annulation Reactions of δ-Acetoxy Allenoates with Cyclic N-Sulfonyl Imines: Divergent Synthesis of Functionalized α-Pyridyl Acetates and Teraryl Scaffolds

J Org Chem. 2020 Mar 20;85(6):4130-4144. doi: 10.1021/acs.joc.9b03281. Epub 2020 Feb 28.

Authors

Sanjeeva K Arupula¹, Asif Ali Qureshi¹, K C Kumara Swamy¹

Affiliation

¹ School of Chemistry, University of Hyderabad, Hyderabad 500 046, Telangana, India.

PMID: 32043357
DOI: 10.1021/acs.joc.9b03281

Abstract

Under metal-free conditions, δ-acetoxy allenoates react with cyclic N-sulfonyl imines (sulfamidate imines/sulfonyl imines) to afford functionalized 2-pyridinyl acetates (α-pyridyl acetates) or teraryl motifs by a simple Lewis base switch. Thus, while DBU/Na₂CO₃ combination-directed [3 + 3] annulation involves sulfonyl elimination via O-S or C-S bond cleavage, affording 2-pyridinyl acetates, Ph₃P-catalyzed [4 + 2] annulation leads to functionalized teraryls via Mannich coupling and C-N bond cleavage with retention or cleavage of the sulfamoyloxy group depending on the reaction conditions.