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. 2010 Jun 4;12(11):2524-7.
doi: 10.1021/ol100751n.

Nucleophilic substitution of oxazino-/oxazolino-/benzoxazin [3,2-b]indazoles: an effective route to 1H-indazolones

Michael B Donald  1 , Wayne E Conrad, James S Oakdale, Jeffrey D Butler, Makhluf J Haddadin, Mark J Kurth
Affiliations

Nucleophilic substitution of oxazino-/oxazolino-/benzoxazin [3,2-b]indazoles: an effective route to 1H-indazolones

Michael B Donald et al. Org Lett. .

Abstract

A variety of nucleophiles, thiolates, alkoxides, amines, iodide, and cyanide, react with oxazino-, oxazolino-, and benzoxazin[3,2-b]indazoles under microwave conditions to yield a diverse set of 2-substituted 1H-indazolones. The synthetic utility of these indazoles is further demonstrated by ANRORC (addition of the nucleophile, ring-opening, and ring closure) reactions to yield isomeric pyrazoloindazolones by a process wherein iodide acts first as a nucleophile and subsequently as a leaving group.

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Figures

Scheme 1
Scheme 1
Nucleophilic opening of oxazolo[3,2-b]indazoles.
Scheme 2
Scheme 2
Dealkylative indazole → indazolone conversion.
Scheme 3
Scheme 3
Potassium iodide mediated ANRORC reaction of 6.
Scheme 4
Scheme 4
Potassium iodide reaction with indazole 2c.
Scheme 5
Scheme 5
ANRORC and elimination reactions with indazole 5.
Scheme 6
Scheme 6
Alkoxide-mediated chemistry of indazoles 2b and 2d.
See this image and copyright information in PMC

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