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Synthesis of 2,4-diaminopyrrolo[2,3-d]pyrimidines via thermal fischer indolization. Pyrazole formation with ytterbium triflate catalysis

✍ Scribed by Gordon L. Bundy; Theresa M. Schwartz; John R. Palmer; Lee S. Banitt; William Watt

Publisher
Journal of Heterocyclic Chemistry
Year
2000
Tongue
English
Weight
515 KB
Volume
37
Category
Article
ISSN
0022-152X

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✦ Synopsis

Abstract

The high‐yield synthesis of the 2,4‐diaminopyrrolo[2,3‐d] pyrimidine 4 (PNU‐87663) via a Bischler‐like alkylation‐cyclization sequence was reported earlier. We describe herein an alternative synthesis of this potent antioxidant and several analogs based on the thermal Fischer indolization, starting from hydrazino substituted pyrimidines 5 and 13. In several cases where the thermal Fischer indolization failed, attempts to catalyze the reaction with Lewis acids, especially ytterbium triflate, led to the surprising and unprecedented formation of pyrazolo[3,4‐d]pyrimidines, e.g. 1‐methyl‐3‐phenyl‐4,6‐di‐1‐pyrrolidinyl‐1__H__‐pyrazolo[3,4‐d]pyrimidine (24), with the loss of the elements of methane. Mechanistic details of this transformation remain to be investigated.

📜 SIMILAR VOLUMES

ChemInform Abstract: Synthesis of 2,4-Di
ChemInform Abstract: Synthesis of 2,4-Diaminopyrrolo[2,3-d]pyrimidines via Thermal Fischer Indolization. Pyrazole Formation with Ytterbium Triflate Catalysis.
✍ Gordon L. Bundy; Theresa M. Schwartz; John R. Palmer; Lee S. Banitt; William Wat 📂 Article 📅 2010 🏛 John Wiley and Sons ⚖ 34 KB

## Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable v

Unusual dihydrazone formation in the fis
Unusual dihydrazone formation in the fischer-indole cyclization. The synthesis of novel nonclassical annulated 2,4-Diamino-pyrrolo[2,3-d]pyrimidine antifolates
✍ Aleem Gangjee; Lihua Chen 📂 Article 📅 1999 🏛 Journal of Heterocyclic Chemistry 🌐 English ⚖ 323 KB

## Abstract The synthesis of seven novel tetracyclic 2,4‐diaminopyrrolo[2,3‐__d__]pyrimidines as conformationally restricted nonclassical antifolates was achieved __via__ an unusual Fischer‐indole cyclization of dihydrazones. An attempted synthesis of 2,4‐diamino‐6‐hydrazinopyrimidine afforded 2‐am