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Synthesis 2007(21): 3371-3375
DOI: 10.1055/s-2007-990817
DOI: 10.1055/s-2007-990817
PAPER
© Georg Thieme Verlag Stuttgart · New York
An Efficient Synthesis of 2-Diazo-2-(trimethylsilyl)ethanols and Their Application to Pyrazole Synthesis
Further Information
Received
9 July 2007
Publication Date:
10 October 2007 (online)
Publication History
Publication Date:
10 October 2007 (online)
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Abstract
Reaction of diazo(trimethylsilyl)methylmagnesium bromide with aldehydes or ketones gave 2-diazo-2-(trimethylsilyl)ethanols, which were applied to the synthesis of di- and trisubstituted pyrazoles via [3+2] cycloaddition reaction with ethyl propiolate or dimethyl acetylenedicarboxylate.
Key words
diazoalcohol - 2-diazo-2-(trimethylsilyl)ethanols - diazo(trimethylsilyl)methylmagnesium bromide - pyrazoles - trimethylsilyldiazomethane
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References
When, during the workup of 2a, the organic extracts were not washed with aq sat. NaHCO3, no final product 3a was obtained after the reaction with DMAD.
12The position of the ethoxycarbonyl group in 4 was determined by NOE measurement (Figure [1] ). For example:
Figure 1 NOE data for 4