Naphthacene hydrogenation

It was found that the Et3SiH and boron trifluoride monohydrate (a strong acid compatible with Et3SiH) ionic hydrogenation system produces partially hydrogenated anthracene [Eq. (11.77)] and naphthacene in excellent yield under mild conditions 240... 

Photolysis, in the presence of oxygen, of alkenes containing an ally lie hydrogen atom leads to the formation of hydroperoxides. The sensitized process is more efficient, and often yields photoproducts different in structure from those obtained by nonsensitized photooxidation. Cyclohexadiene and related dienes on photolysis in the presence of oxygen yield the transannular peroxides. Thus, on photosensitized oxidation, a-terpinene (410) is converted into ascaridole (411).435 The equivalent process is not, in general, observed in acyclic dienes. Certain polynuclear aromatic hydrocarbons, such as anthracene and naphthacene and including the heterocycles 5,10-diphenyl-1-... 

Inokuchi, H. Catalytic Behavior of Organic Semiconductors. Hydrogen Exchange on Barium-Naphthacene Ion Salts. J. Catalysis 15, 417 (1969). 

In a study dealing with the construction of a 5 -aza-naphthacene derivative, conditions of the radical reaction did not affect the SMA framework present in the starting material. This result could be explained either by the steric hindrance of the silyl group that inhibits the abstraction of the benzylic hydrogen atom to create the corresponding radical species, or this radical, if created, is too stable to react efficiently.153... 

Partial hydrogenation of aromatic rings can also be accomplished with catalysts such as [Co2(CO)g] under an atmosphere of carbon monoxide and hydrogen, but the isolated benzene nucleus cannot be re-duced. ° Anthracene (57), naphthacene, perylene (61) and pyrene (63) are converted to 9,10-dihydroan-thracene (60), 5,12-dihydronaphthacene, 1,2,3,10,11,12-hexahydroperylene (62) and 4,5-dihydropyrene (64), respectively. 

In the presence of molten SbCls, anthracene and naphthacene are selectively hydrogenated by tetralin to give 9,10-dihydroanthracene and 5,12-dihydronaphtha-cene, respectively [31]. Both SbCls-Al and SbCls-Zn binary systems reduce a variety of aldehydes to the corresponding primary alcohols in DMF-H2O (Scheme 14.10) [32]. In the presence of a catalytic amount of SbCl3, acetophenones are reduced to 1-arylethanols by an electrochemical method [33]. Nitroarenes are reduced by Sb-NaBH4 in MeOH [34], and by Sb(.l, -Nal H4 in EtOH [35] to afford N-arylhydroxylamines (Scheme 14.11) and anilines (Scheme 14.12), respectively. 

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