The Effect of Position Replacement of Functional Groups on the Stepwise character of 1,3-Dipolar Reaction of a Nitrile Oxide and an Alkene

• Published in: Helvetica chimica acta Vol. 99; no. 4; pp. 273 - 280
• Main Author: Siadati, Seyyed Amir
• Format: Journal Article
• Language: English
• Published: Zürich Blackwell Publishing Ltd 01.04.2016; Wiley Subscription Services, Inc
• Subjects: 1,3‐Dipolar cycloaddition reaction; 3-Dipolar cycloaddition reaction; Concerted; Functional group effect; Reaction mechanism; Reaction pathways; Stepwise
• ISSN: 0018-019X; 1522-2675
• DOI: 10.1002/hlca.201500165

It is a well‐known fact that by changing the 1,3‐dipolar cycloaddition (1,3‐DC) reaction mechanism from concerted to stepwise, the stereospecificity is lost; since in synthesizing the required heterocyclic molecules that reaction is a requisite, it is important to study the concertedness of that reaction. Several papers on this subject have already stated that the existence of electron withdrawing groups (EWG) or electron donor groups (EDG) on dipole or dipolarophile leads to a high‐energy differentiation between the dipole HOMO and dipolarophile LUMO (or vice versa) as well as the emergence of an intermediate in the reaction pathway. This paper seeks answering the question of when an EWG on dipole and an EDG on dipolarophile could be a factor in making the reaction mechanism stepwise, and does repositioning of functional groups in replacing dipole and dipolarophile switches the reaction mechanism from stepwise into concerted or vice versa?