Synthesis 2022; 54(04): 965-974
DOI: 10.1055/s-0040-1719838
special topic
Cycloadditions – Established and Novel Trends – in Celebration of the 70th Anniversary of the Nobel Prize Awarded to Otto Diels and Kurt Alder

Stereo- and Regioselective [3+2] Cycloaddition of Acetoxy Allenoates with Azides: Metal-Free Synthesis of Multisubstituted Triazoles

Asif Ali Qureshi
,
Arpula Sanjeeva Kumar
,
Sachin Chauhan
,
K. C. Kumara Swamy
Funding and fellowships came from the Science and Engineering Research Board (SERB) as a J. C. Bose fellowship (JBR/2020/000038), the University Grants Commission (UGC), the Dr. D. S. Kothari Postdoctoral Fellowship Scheme (DSKPDF), and the University of Hyderabad.


Abstract

We have developed a regio- and stereoselective thermal [3+2]-cycloaddition protocol involving acetoxy allenoates as 1,2-dipoles under metal-free conditions for the synthesis of 1,4,5-tri/1,5-disubstituted 1,2,3-triazoles. δ-Acetoxy allenoates act as α- and β-carbon donors and lead to trisubstituted 1,2,3-triazoles with an alkenyl functionality at the 5-position. In sharp contrast to this, β- and γ-carbons participate in the case of β′-acetoxy allenoates to afford 1,5-disubstituted triazole cores. This [3+2] cycloaddition shows a broad substrate scope concerning acetoxy allenoate as well as azide and offers essentially E-stereoisomers in good to high yields. Divergently, the reaction of δ-acetoxy allenoate with trimethylsilyl azide gives an acyclic, nitrogen-inserted product with the cleavage of C–C bonds.

Supporting Information



Publication History

Received: 17 July 2021

Accepted after revision: 18 August 2021

Article published online:
12 October 2021

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