Cycloadditions and other chemistry of 4-oxygenated pyrazoles
نویسندگان
چکیده
منابع مشابه
Catalytic, enantioselective [4 + 2]-cycloadditions of ketene enolates and o-quinones: efficient entry to chiral, alpha-oxygenated carboxylic acid derivatives.
We report catalytic, enantioselective [4 + 2]-cycloadditions of o-quinones with ketene enolates (derived from readily available acid chlorides) using cinchona alkaloid derivatives as catalysts to produce products in high enantiomeric excess (ee) and good to excellent yields. The thermodynamic driving force for these reactions is due in part to the restoration of aromaticity to the products. The...
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Selective synthesis of 4-(sulfonyl)-methyl-1H-pyrazoles and (E)-4,5-dihydro-1H-pyrazoles from N-allenic sulfonylhydrazones with sulfonyl group migrations has been developed. A key feature of these reactions is that the migrations of the sulfonyl groups to different positions can be controlled by changing the Lewis acids.
متن کاملSynthesis of Dihydrooxepino[3,2-c]Pyrazoles via Claisen Rearrangement and Ring-Closing Metathesis from 4-Allyloxy-1H-pyrazoles.
Synthesis of novel pyrazole-fused heterocycles, i.e., dihydro-1H- or 2H-oxepino[3,2-c]pyrazoles (6 or 7) from 4-allyloxy-1H-pyrazoles (1) via combination of Claisen rearrangement and ring-closing metathesis (RCM) has been achieved. A suitable catalyst for the RCM of 5-allyl-4-allyloxy-1H-pyrazoles (4) was proved to be the Grubbs second generation catalyst (Grubbs2nd) to give the predicted RCM p...
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ژورنال
عنوان ژورنال: Canadian Journal of Chemistry
سال: 1979
ISSN: 0008-4042,1480-3291
DOI: 10.1139/v79-149