On the ozonolysis of unsaturated tosylhydrazones as a direct approach to diazocarbonyl compoundsElectronic supplementary information (ESI) available: Copies of 1H NMR and 13C NMR spectra of all new compounds. NOE and s-E/s-Z NMR study of 41. X-ray data for compound 35. CCDC 1815202. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c8ob00435h
The scope and limitations are described of reacting unsaturated tosylhydrazones with O 3 followed by Et 3 N for the generation of 1,4- and 1,5-diazocarbonyl systems. Tosylhydrazones, from tosylhydrazide condensation with readily available δ- and -unsaturated α-ketoesters, led in the former case to a...
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Main Authors | , , , , , , |
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Format | Journal Article |
Published |
25.04.2018
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Online Access | Get full text |
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Summary: | The scope and limitations are described of reacting unsaturated tosylhydrazones with O
3
followed by Et
3
N for the generation of 1,4- and 1,5-diazocarbonyl systems. Tosylhydrazones, from tosylhydrazide condensation with readily available δ- and -unsaturated α-ketoesters, led in the former case to a 2-pyrazoline whereas the latter cases led to α-diazo- -ketoesters, although a terminal alkene produced a tetrahydropyridazinol. Using the ozonolysis-Et
3
N strategy, tosylhydrazones from cyclic enones give 2,5- and 2,6-diazoketones with aldehyde or ester functionality at the 1-position; the α-diazoaldehydes prefer the s-
trans
conformation, with a rotation barrier of 74 kJ mol
−1
at 25 °C determined by NMR. This one-pot ozonolysis/Bamford-Stevens chemistry demonstrates both the tolerance of tosylhydrazones to ozone, and the subsequently added amine playing a dual role to directly transform the intermediate tosylhydrazone ozonides into products containing reactive diazo and ketone functionalities; such adducts are of particular value as precursors to cyclic carbonyl ylides for 1,3-dipolar cycloadditions.
Chemoselective alkene ozonolysis of unsaturated hydrazones then addition of Et
3
N simultaneously reveals synthetically valuable carbonyl and (
via
Bamford-Stevens) diazo functionality. |
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Bibliography: | CCDC 13 35 1815202 ray data for compound s-E 10.1039/c8ob00435h Electronic supplementary information (ESI) available: Copies of . / Z NMR study of 1 H NMR and For ESI and crystallographic data in CIF or other electronic format see DOI C NMR spectra of all new compounds. NOE and s X 41 |
ISSN: | 1477-0520 1477-0539 |
DOI: | 10.1039/c8ob00435h |