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A Flexible Strategy for the Regiocontrolled Synthesis of Pyrazolo[1,5-a]pyrazines

Peter J. Lindsay-Scott*, Natalie G. Charlesworth and Alexandru Grozavu

*Eli Lilly and Company Limited, Erl Wood Manor, Windlesham, Surrey GU20 6PH, United Kingdom, Email:

P. J. Lindsay-Scott, N. G. Charlesworth, A. Grozavu, J. Org. Chem., 2017, 82, 11295-11303.

DOI: 10.1021/acs.joc.7b02128

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Commercially available pyrazoles were alkylated and formylated in a regiocontrolled manner to give pyrazole-5-aldehydes bearing 2,2-dialkoxyethyl substitution on N-1. Subsequent deprotection and cyclization of these intermediates allowed access to pyrazolo[1,5-a]pyrazines with multiple substitution patterns, whereas a deprotection and double-reductive amination sequence provides 4,5,6,7-tetrahydropyrazolo[1,5-a]pyrazines.

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Key Words

benzo-fused N-heterocycles

ID: J42-Y2017