135127-35-4

Upstream product

• 6830-78-0 3,6-diphenyl-1,2,4,5-tetrazine 
• 120-46-7 1,3-diphenylpropanedione 
• 134390-36-6 2,2-dimethoxy-1,3-diphenyl-1,3-propanedione 
• 1155-77-7 1,2,3,4-tetrachloro-5-phenyl-7,7-dimethoxybicyclo<2.2.1>hepta-2,5-diene 

Downstream Products

• 15599-02-7 5,6,7,8-Tetrahydro-1,4-diphenyl-5,8-methanophthalazine 
• 440085-24-5 endo-2,3-diaza-10,10-dimethoxy-1,4-diphenyltricyclo[5.2.1.5,9]dec-2-ene 

Relevant academic research and scientific papers

1,2-Diazacyclopentane-3,5-diyl Diradicals: Electronic Structure and Reactivity

Localized singlet diradicals are key intermediates in bond homolysis. A thorough study of the reactive species is needed to clarify the mechanisms of the homolytic bond cleavage and formation processes. In general, the singlet diradicals are quite short-lived because of the fast radical-radical coupling reactions. The short-lived characteristic has retarded the thorough study on bond homolysis. In this study, a new series of long-lived singlet diradicals, viz., 1,2-diazacyclopentane-3,5-diyl, were identified, and their electronic structures and novel reactivities were thoroughly studied using laser-flash photolysis (LFP), product analysis, and computational studies. A direct observation of the thermal equilibration (fast process) between the singlet diradicals and the corresponding ring-closing compounds was undertaken on the submicrosecond time scale. The solvent and substituent effects on the equilibration constant and rate constants for the ring-closing reaction and ring-opening reaction clarify the novel nitrogen-atom effect on the localized singlet 1,3-diyl diradicals. Two types of alkoxy-migrated compounds, 9 and 10, were isolated with high yields as the final products. Crossover, spin-trapping, and LFP experiments for the formation of alkoxy-group migration products (i.e., 9 versus 10) revealed the unique temperature effect on the product ratio of the two types of alkoxy-migration products. The temperature-insensitive intersystem crossing process (slow process, millisecond time scale) was found to be a key step in the formation of 9, which is an entropy-controlled pathway. An intramolecular migration process was identified for the formation of 10 that was accelerated by a polar solvent in an enthalpy-controlled process. This unique heteroatom effect has opened up a new series of localized singlet diradicals that are crucial intermediates in bond homolysis.

On the electronic character of localized singlet 2,2-dimethoxycyclopentane-1,3-diyl diradicals: Substituent effects on the lifetime

Photodenitrogenation of the diazenes 4 affords exclusively the housanes 5 through intramolecular cyclization of the spectrally detected and characterized singlet diradicals 3. The lifetime of singlet diradical 3, determined by transient absorption measure

+ + 2> Cycloadditions with an N-Methyl-4H-pyrazolium Cation as Electron-Deficient Diazadiene System

3,6-Diphenyl-1,2,4,5-tetrazine (6) reacts with dimethoxycarbene (7), generated from the 1,3,4-oxadiazoline 8, to yield the 4H-pyrazole 10.This is alkylated to the N-methyl-4H-pyrazolium tetrafluoroborate 12 in good yield.The alkylated, cationic azine syst

Nucleophilic Singlet Carbenes in the Cycloaddition with 1,2,4,5-Tetrazines: a New Synthesis of Isopyrazoles

A series of 3,6-disubstituted 1,2,4,5-tetrazines 6, including C6H5, SCH3, SO2CH3, N(CH3)2, CF3, CO2CH3 groups, has been submitted to cycloaddition with the nucleophilic singlet carbenes 4, 15, and 20, which are generated from the precursors 1, 11 and 19, resp.In all cases isopyrazoles (4H-pyrazoles) 9, 10, 18, and 21 are isolated in good yields.They are formed in a two-step reaction sequence with the cycloadducts of type 8 as intermediates which eliminate nitrogen by subsequent cycloreversion.The acceptor-substituted isopyrazole 9e is characterized as an electron-deficient diene by some Diels-Alder reactions with inverse electron demand leading to the expected azo-bridged cycloadducts 23, 25, 27, 29, and 31 without acid catalysis or aplication of higher pressure.With cyclooctyne (32), the cycloaddition is followed by a cycloreversion with formation of the cyclopentacyclooctene 34.Key Words: Singlet Carbenes / Cycloadditions / Isopyrazoles / Diels-Alder reactions / Cycloreversion

Nucleophile singulett-carbene in der inversen [4+]-cycloaddition: Eine neue isopyrazol-synthese

Dimethoxycarbene, generated from the norbornadienone ketal 6 or from triethyl orthoformate 12a can be trapped by various 1,2,4,5-tetrazines 1 to yield the corresponding isopyrazoles 10 in high yields via [4+1]-cycloaddition followed by [4+2]-cycloreversio