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Synthesis 2020; 52(01): 105-118
DOI: 10.1055/s-0037-1610734
paper
© Georg Thieme Verlag Stuttgart · New York

Regiocontrolled Synthesis of 6,7-Dihydro-4H-pyrazolo[5,1-c][1,4]oxazines

Peter J. Lindsay-Scott∗
Eli Lilly and Company Limited, Erl Wood Manor, Windlesham, Surrey GU20 6PH, UK   Email: lindsay-scott_peter@lilly.com
,
Eloise Rivlin-Derrick
› Author Affiliations
Further Information

Publication History

Received: 27 August 2019

Accepted after revision: 17 September 2019

Publication Date:
08 October 2019 (online)

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Abstract

Synthetic access to 6,7-dihydro-4H-pyrazolo[5,1-c][1,4]oxazines has been achieved in 3–4 steps from commercially available pyrazoles. Optimization of a protected hydroxyethyl group on N1 enabled the regiocontrolled construction of pyrazole-5-aldehydes in high yields; subsequent deprotection and reduction generated fused heterocyclic scaffolds bearing multiple substitution patterns. Moreover, the intermediate pyrazole lactols were shown to be versatile synthetic building blocks.

Key words

heterocycles - pyrazoles - oxazines - regioisomers - cyclization

Supporting Information

    Supporting information for this article is available online at https://doi.org/10.1055/s-0037-1610734.
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