789. Conjugated macrocycles. Part XXXI. Catalytic hydrogenation of tetrazaporphins, with a note on its stereochemical course

Synthesis and Spectroscopic and Electrochemical Studies of Novel Benzo‐ or 2,3‐Naphtho‐Fused Tetraazachlorins, Bacteriochlorins, and Isobacteriochlorins

“…[5,6] However, in these TACs and TABCs, substitution effects could not be completely excluded from the interpretation of the spectroscopic properties, since aromatic substituents possibly interact with aromatic macrocycles through coupling of transition dipole moments. As another example of a ringhydrogenated derivative, Hoffman×s group showed that an unsymmetrical TAP could be converted into the corresponding cis-dihydroporphyrazinediol upon reaction with OsO 4 . This diol further underwent reaction with Ni(OAc) 2 in the presence of air to give a seco-porphyrazine with a cleaved pyrrole b,b'-bond.…”

“…General approaches to hydrogenated TAP derivatives frequently cause auto-oxidation at the hydrogenated sites and give rise to non-hydrogenated compounds or even decomposition of the molecule. The first and until recently the only attempt to prepare hydrogenated derivatives of TAP was by Linstead et al in 1958, [4] in which TACs were synthesized by catalytic hydrogenation of alkylsubstituted MgTAPs in the presence of Pd black, although the TAC structures were not characterized sufficiently. Recently, well-characterized dibenzobarreleno-substituted metal-free TACs and TABCs were prepared by one of our groups by using the Diels±Ald-er reaction of an unsubstituted TAP as dienophile and anthracene derivatives as dienes.…”

Electronic excited states of small ring compounds. VII. Bicyclo[2.1.0]pentanes by the photocycloaddition of 1,2,3-triphenylcyclopropene to fumaro- and maleonitrile

“…The thermodynamic equilibrium has been established in a thermal reaction (180°C), catalyzed by iodine. The reported equilibrium value (33.8% 8) (22) was based upon isolated yields and differs from the value we obtain (43.5% 8 at 180°C; AG = 0.2 kcal mol-I) by vpc analysis of the crude reaction mixture. We believe it is fortuitous that the thermodynamic equilibrium is so similar to the photosensitized stationary state value.…”

Phthalocyanine, Porphyrin, Cyclodextrin, and Polymer Systems Suitable for Studying by Circular Dichroism, Magnetic Circular Dichroism, and/or Electrochemistry

“…Accordingly, following aromatic ring-fused low symmetry compounds, we decided to examine hydrogenated TAPs. Hydrogenated TAPs were first synthesized by Linstead et al in 1958, 34 but these compounds were not well elucidated because of the tendency to return to unsaturated TAPs or even to degradated products. In 2000, this problem was overcome by Makarova, Luk'yanets, et al, by introducing bulky substituent groups which prevent coplanarization of two CH bonds at adjacent pyrrole ¢-carbons.…”