Azodicarboxylates isobomyl azodicarboxylate

The preparation of chiral dialkylazodicarboxylates and their use as electrophilic enolate animation reagents, were first reported in 1995 by Vederas and co-workers [51]. A series of chiral dialkyl (menthyl 97a, bomyl 97b, isobomyl 97c) azodicarboxylates were prepared by conversion of the corresponding alcohols into chloro-formates, condensation with hydrazine and oxidation with IV-bromosuccinimide and pyridine. Compounds 97 were obtained in 35-50% yield (Scheme 45). 

Anions generated from tertiary amides preferentially assumed the Z-configura-tion. Reaction of MA-dimethylamides with 1 equiv. of LDA at -78 °C followed by addition of 1.5 equiv. of di(-)-isobomyl azodicarboxylate 97c gave in each case a 1 1 ratio of diastereomers (/ )-99 and (S)-99 (Table 3.10, entries 7 and 8). Double diastereoselection was tested with chiral enolates enantiomerically pure /V-acyloxazolidinone (S)-100 and its enantiomer (/ )-100 were aminated at -78 °C with 97c (Scheme 47). 

DIELS-ALDER DIENOPHILES Bis(2,2,2-trichloroethyl) azodicarboxylate. 1-Bromo-2-chlorocyclopropene. Chromium carbene complexes. (R)-Ethyl p-tolysulfinyl-methylenepropionate.l (S)-a-Hydroxy-p,p-dimethylpropyl vinyl iketone. (IR)-m-3-Hydroxy isobomyl ndopentyl ether. Oxa-zolidones, chiral. Phdnylselenenyl ben-zenesulfonate. 

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See also in sourсe #XX -- [ , ]

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