Leukart reaction

Poly(N-alkyl-ethylene imine) can be prepared by cationic ring-opening polymerization of N-alkylaziridines however, branched polymers are obtained by this way 19>. Linear poly-MEI may be obtained by N-methylation of linear PEI by the Clarke-Eschiweiler variation of the Leukart reaction, in which an excess of formic acid is used together with formaldehyde. The reaction may be performed either on PEI, or... 

Acetyl thiadiazole also displays enhanced reactivity in both the carbonyl and the methyl groups and enters the aldol condensation, the Mannich reaction, cyanoethylation reaction, the Willgerodt reaction, the Leukart reaction and borohydride reduction, all in high yield under very mild conditions (68AHC(9)107). 

The Leukart reaction has also been used in the conversion of dehydroepiandro-sterone into 17/3-formylamino-3/3-formyloxyandrost-5-ene, which on reduction with lithium aluminium hydride afforded 3/3-hydroxy-17/3-me thylaminoandrost-5-ene. Acylation with isocaproyl chloride then furnished the N-methyl-N-isocaproyl steroid (197), after selective ester hydrolysis of the initially formed ON-diacyl derivative. The amide (197) was further converted into its 3,5-cyclo-6-ketone via the 3,5-cyclo-6/3-alcohol and thence by reaction with hydrogen bromide into the corresponding 3/3-bromo-5a-6-ketone which upon dehydrobromination furnished a A2-5a-6-ketone and ultimately the 2-monoacetate of the 2/3,3/3-diol (198) after reaction with silver acetate and iodine. Hydrolysis to the 2/3,3/3-diol (198) gave a separable mixture of the 2/3,3/8-dihydroxy-5a- and -5/3-ketones.88... 

The behavior of 3-acetyl-l,2,5 thiadiazole (87) in several reduction reactions was also studied. The Leukart reaction produced the expected product, l-[3-(l,2,5-thiadiazolyl)]ethylamine, but the Wolff-Kishner reaction failed to yield any ethylthiadiazole under various conditions examined. Sodium borohydride smoothly reduced both acetyl- and benzoylthiadiazole to the corresponding carbinols. 

Leuckart (Leukart) Reaction Leuckart-Wallach Reaction Eschweiler-Clarke Reaction... 

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