Synthetic method of polycyclic 2-hydropyrazoles
A technique for the synthesis of hydropyrazoles, which is applied in organic chemistry and other fields, can solve the problems of 2-hydropyrazoles such as harsh conditions, narrow substrate applicability, and regioselectivity, and achieve wide substrate applicability , Green and efficient to obtain the effect without catalyst
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Embodiment 1
[0048] This embodiment provides a synthetic method for polycyclic 2-hydropyrazole compounds, the reaction formula is as follows (Me represents methyl):
[0049]
[0050] Add raw material 1a (0.2mmol), sulfuric acid aqueous solution (1.7M, 0.4mL, 3.4eq) into the reaction flask, add 2mL mixed solvent (by volume ratio, DMF:H 2 O=1:3) dissolve and slowly add NaNO 2 (18mg, 1.3eq), slowly rise to room temperature and stir for 7 hours, add 30mL H 2 O, after standing for 1 hour, the solid precipitate was filtered with a Buchner funnel, washed with water and n-hexane in turn, and dried under an infrared lamp for 12 hours to obtain the purified polycyclic 2-hydropyrazole compound 2a, which is Yellow solid, >95% purity, 95% yield.
[0051] The obtained product 2a is characterized by nuclear magnetic resonance, such as figure 1 The H spectrum shown and figure 2 In the shown C spectrum, the deuterated reagent used for NMR characterization is DMSO.
Embodiment 2
[0053] This embodiment provides a synthetic method of polycyclic 2-hydropyrazole compounds, the reaction formula is as follows:
[0054]
[0055] Add raw material 1b (0.2mmol), glacial acetic acid aqueous solution (1.9M, 0.13mL, 1.2eq) into the reaction flask, add 2.0mL CH at -20°C 3 Dissolve CN (acetonitrile) and slowly add NaNO 2 (19mg, 1.35eq), slowly rise to room temperature and stir for 24 hours, add 30mL H 2O, after standing for 1 h, the solid precipitate was filtered with a Buchner funnel, washed with water and n-hexane in turn, and dried under an infrared lamp for 8 hours to obtain the purified polycyclic 2-hydropyrazole compound 2b, which was yellow Solid, >95% purity, 90% yield.
[0056] The obtained product 2b is characterized by nuclear magnetic resonance, such as image 3 The H spectrum shown and Figure 4 In the shown C spectrum, the deuterated reagent used for NMR characterization is DMSO.
Embodiment 3
[0058] This embodiment provides a synthetic method of polycyclic 2-hydropyrazole compounds, the reaction formula is as follows:
[0059]
[0060] Add raw material 1c (0.2mmol), methanesulfonic acid aqueous solution (1.8M, 0.4mL, 3.6eq) into the reaction flask, add 2.0mL mixed solvent (by volume ratio, acetone:H 2 O=1:4) dissolve and slowly add KNO 2 (24.6mg, 1.45eq), slowly rise to room temperature and stir for 8 hours, add 30mL H 2 O, after standing for 3 hours, the solid precipitate was filtered with a Buchner funnel, washed with water and n-hexane in turn, and dried under an infrared lamp for 9 hours to obtain the purified polycyclic 2-hydropyrazole compound 2c, which is Yellow solid, >95% purity, 91% yield.
[0061] The obtained product 2c is characterized by nuclear magnetic resonance, such as Figure 5 The H spectrum shown and Figure 6 In the shown C spectrum, the deuterated reagent used for NMR characterization is DMSO.
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