Nitric oxide cycloaddition

Diazotization of 3-(4-aminophenyl)sydnones followed by reaction with 1- or 2-hydroxynaphthalene provides azo dyestuff materials <1998MI209>. A new type of reaction between 4-acetyl-3-arylsydnones and hydrazine yields substituted pyrrolidinones by a cycloaddition process involving loss of nitric oxide (Equation 20) <1999H(51)95, 2001AHC73>. 

A very remote secondary H/D isotope effect has been measured for the 2 + 2-cycloaddition of TCNE to 2,7-dimethylocta-2,fran -4,6-triene. The reaction of nitric oxide with iV-benzylidene-4-methoxyaniline to produce 4-methoxybenzenediazonium nitrate and benzaldehyde is thought to proceed via a 2 + 2-cycloaddition between nitric oxide and the imine double bond. A novel mechanism for the stepwise dimerization of the parent silaethylene to 1,3-disilacyclobutane involves a low-barrier [1,2]-sigmatropic shift. Density functional, correlated ab initio calculations, and frontier MO analysis support a concerted 2 + 2-pathway for the addition of SO3 to alkenes. " The enone cycloaddition reactions of dienones and quinones have been reviewed. The 2 + 2-photocycloadditions of homochiral 2(5H)-furanones to vinylene carbonate are highly diastereoisomeric. ... 

This chapter covers the literature from mid-1995 to mid-2007. Recent advances include the preparation of the first A2-l,2,3,4-oxatriazolines 7 by intramolecular [3+2] cycloaddition (Section 6.08.9), synthesis of mesoionic derivatives 4 using bromonitroformaldehyde iV-arylhydrazones as the starting materials (Section 6.08.9), and detailed studies of the biologically active mesoionic oxatriazoles in the context of their nitric oxide donating capabilities (Section... 

Dihydrotetrazine 32 was oxidized with nitric acid in acetic acid to yield tetrazine 45 which suffered cycloaddition with acetylene in refluxing DMF followed by the extrusion of nitrogen to give pyridazine 46 which was used as bis-tridentate bridging ligand <02OL1253>. 

Nitric acid oxidation of the corresponding monomethoxy precursors yielded three isomeric phenanthrolinequinones, 252-254 (50HCA1080). The linear analogs 255 and 256 were prepared by cycloaddition of l-(dimethyl-amino)-3-methyl-l-azabuta-1,3-diene to the corresponding bicyclic quinones (87JOC2285). 

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