Diazo Functional Groups Research Articles

Kinetics and mechanism of acid‐catalyzed hydrolysis of the diazo functional group of diazophenylacetamide

AbstractThe acid‐catalyzed hydrolysis of diazophenylacetamide giving mandelamide as product was found to occur with a normal (kH/kD>1) hydronium ion isotope effect and to be subject to general acid rather than specific hydronium ion catalysis. This shows that the reaction occurs by rate‐determining hydron transfer from the catalyzing acid to the diazo carbon atom of the substrate, followed by rapid displacement of the diazo group by water. Comparison of the rate of this reaction with those of the same process for other diazophenylacetic acid functional derivatives, PhCN2COX, reveals that the reactivity of these substrates is controlled by the electron‐releasing resonance ability of the group X. Copyright © 2003 John Wiley & Sons, Ltd.

Microwave specific Wolff rearrangement of alpha-diazoketones and its relevance to the nonthermal and thermal effect.

alpha-Diazoketones possess high electric dipole moments, as a consequence of the dipolar nature of the diazocarbonyl functional group. The vectorial analysis, theoretical calculations (PM3 and ab initio), and literature reports based on experimental and theoretical calculations reveal a higher dipole moment for the Z-configuration of the diazo functional group. Microwave irradiation of alpha-diazoketone (1a-m) (Figure 1) promotes Wolff rearrangement specifically via the Z-configuration in excellent yields. The dielectric properties of the solvent govern the course of the microwave rearrangement. 3-Diazocamphor (1m) on microwave irradiation in benzylamine exhibits nonthermal effects to furnish exclusively the Wolff rearrangement product (4m), equivalent to its photochemical behavior. In the presence of an aqueous medium, through solvent heating predominates, leading to the formation of a tricyclic ketone (5) as the principal product, arising from an intramolecular C-H insertion. This behavior is similar to its known thermal and transition metal catalyzed reactivity pattern.

2,3,7‐Triazabicyclo[3.3.0]octenes Prepared by Tandem Cascade Reaction of Allyl Azides and Olefinic Dipolarophiles

AbstractTandem cascade reactions of allylazides and olefinic dipolarophiles to give cis‐fused 2,3,7‐triazabicyclo [3.3.0]octenes (5, 6 or 7) are reported. Therein, an intermolecular dipolar cycloaddition of azide and alkene gave a triazoline which was followed by isomerization of the triazoline to a diazoester (4) and then an intramolecular dipolar cycloaddition from the diazo functional group and the double bond in 4 to give 5. Compound 5 may further more undergo a Michael addition to give 7‐substituted‐ 2,3,7‐ triazabicyclo [3.3.0]oct‐2‐ene (6) or a tautomerization to give 2,3,7‐triazabicyclo[3.3.0]oct‐3‐ene (7). The reaction may be manipulated to stop at a particular stage by adopting a suit able solvent or an appropriate temperature.

Structure and Spectroscopic Properties of p‐Benzoquinone Diazides

AbstractA series of p‐benzoquinone diazides were investigated by 13C‐NMR and IR spectroscopy as well as by semiempirical and abinitio calculations. In addition, X‐ray structure analyses of the parent compound and three derivatives were performed. The electronic structure and effects of substituents can be described in terms of diazoketo and diazonium phenolate resonance structures. While alkyl groups as substituents have only a minor influence on quinone diazides, electron‐withdrawing substituents lead to a larger participation of the aromatic diazonium phenolate structure. Benzoannellation, on the other hand, leads to a decrease of the interaction between the keto and diazo functional group and to properties more reminiscent of “ordinary” ketones and diazo compounds.