Hydrazone

About: Hydrazone is a research topic. Over the lifetime, 4853 publications have been published within this topic receiving 65160 citations. The topic is also known as: hydrazone.

An Old Dog with New Tricks: Enjoin Wolff–Kishner Reduction for Alcohol Deoxygenation and C–C Bond Formations

Abstract: The Wolff–Kishner reduction, discovered in the early 1910s, is a fundamental and effective tool to convert carbonyls into methylenes via deoxygenation under strongly basic conditions. For over a century, numerous valuable chemical products have been synthesized by this classical method. The reaction proceeds via the reversible formation of hydrazone followed by deprotonation with the strong base to give an N-anionic intermediate, which affords the deoxygenation product upon denitrogenation and protonation. By examining the mechanistic pathway of this century old classical carbonyl deoxygenation, we envisioned and subsequently developed two unprecedented new types of chemical transformations: a) alcohol deoxygenation and b) C–C bond formations with various electrophiles including Grignard-type reaction, conjugate addition, olefination, and diverse cross-coupling reactions. 1 Introduction 2 Background 3 Alcohol Deoxygenation 3.1 Ir-Catalyzed Alcohol Deoxygenation 3.2 Ru-Catalyzed Alcohol Deoxygenation 3.3 Mn-Catalyzed Alcohol Deoxygenation 4 Grignard-Type Reactions 4.1 Ru-Catalyzed Addition of Hydrazones with Aldehydes and Ketones 4.2 Ru-Catalyzed Addition of Hydrazone with Imines 4.3 Ru-Catalyzed Addition of Hydrazone with CO2 4.4 Fe-Catalyzed Addition of Hydrazones 5 Conjugate Addition Reactions 5.1 Ru-Catalyzed Conjugate Addition Reactions 5.2 Fe-Catalyzed Conjugate Addition Reactions 6 Cross-Coupling Reactions 6.1 Ni-Catalyzed Negishi-type Coupling 6.2 Pd-Catalyzed Tsuji–Trost Alkylation Reaction 7 Other Reactions 7.1 Olefination 7.2 Heck-Type Reaction 7.3 Ullmann-Type Reaction 8 Conclusion and Outlook

Organocerium Additions to Chiral α,α-Dialkoxy Hydrazones: Asymmetric Synthesis of N-Protected α-Amino Acetals and α-Amino Aldehydes

Abstract: A general and selective procedure for the diastereoselective additions of organocerium reagents to chiral α,α-dialkoxy hydrazones has been developed. The best reagent combination involved a 6:1 composition of RMet to CeCl3. Excellent yields and high selectivities were obtained after trapping as the iso-butyl carbamates. Lithiumammonia cleavage of the N-N bond followed by hydrolysis with TMSI afforded the protected α-amino aldehydes.

Benzophenone semicarbazone protection strategy for synthesis of aza-glycine containing aza-peptides.

Abstract: Aza-glycine has been incorporated into peptide mimics as a tool for studying the active conformation and characterizing structure-function relationships for activity. Side reactions, such as intramolecular cyclizations to form hydantoins and oxadiazalones, have, however, inhibited efforts to make activated aza-Gly residues in solution using carbamate protection. Herein, we describe efficient incorporation of aza-glycine into aza-peptides using diphenyl hydrazone protection. Hydrazone acylation with p-nitrobenzyl chloroformate provided the protected aza-Gly activated ester, which was used to acylate a set of amino ester and amino acids to provide aza-Gly-Xaa aza-dipeptide fragments for peptide synthesis. Removal of the hydrazone protection was performed under acidic conditions to provide the hydrochloride salt of the aza-Gly residue for subsequent elongation of the aza-peptide chain using standard coupling conditions. A proof of concept for the use of benzophenone protection has been established by the synthesis of an aza-peptide analog of a potent activator of caspase 9 in cancer cells.