A Parham Cyclization route to the 2, 3-dihydro-1H-indazole-1, 2-dicarboxylate ring systems via condensation of thermolabile aryllithium reagents and azodicarboxylate esters. Issue 19 (10th May 2017)

• Record Type: Journal Article
• Authors: Farrokh, John; Craven, Timothy; Hunt, David A.
• Is Part Of: Tetrahedron letters. Volume 58:Issue 19(2017)
• Page Start: 1900
• Page End: 1901
• Publication Date: 2017-05-10
• Subjects: Parham Cyclization -- Aryllithium reagents -- Azodicarboxylates -- 2, 3-Dihydro-1H-indazole-1, 2-dicarboxylate; Chemistry, Organic -- Periodicals; 547.005
• DOI: 10.1016/j.tetlet.2017.04.022
• Languages: English
• ISSNs: 0040-4039

Abstract

Graphical abstract: Highlights: The Parham reaction can be applied toward the preparation of the 2, 3-dihydro-1 H -indazole-1, 2-dicarboxylate ring system. o -Lithiobenzyl chlorides react with azodicarboxylate esters at low temperature. This provides a new entry to the 2, 3-dihydro-1 H -indazole-1, 2-dicarboxylate ring system. Yields are moderate to good. Abstract: The Parham Cyclization reaction of o -lithiobenzyl chlorides (generated by low temperature halogen-metal exchange of the corresponding o -bromobenzyl chlorides with n -butyllithium) with azodicarboxylate esters provides a new entry to the 2, 3-dihydro-1 H -indazole-1, 2-dicarboxylate ring system in moderate to good yield.