Anthracen-1.4-imines

The A -ethoxycarbonyl derivative (192) was obtained from 191 with ethyl chloroformate and butyllithium, although p Tidine, triethylamine. 

A preliminary study by NMR spectroscopy has been made of the equilibration of N-invertomers for the anthracen-9,10-imine (195).  

Compounds 185 and 190 add methyl iodide to give crystalline quaternary salts,one of which (196) resolidifies on heating above its melting point 130°, possibly forming the isomeric salt 198. 

Benzyne reacts with 185 to give 17% of the ring-opened 1 1 adduct (203) and 9% of anthracene. The formation of 203 is explained by a 

Both compounds 190 and 193 are reduced to 9,10-diphenylanthracene (205) by zinc and acetic acid. However, more interest attaches to the formation of anthracenes from anthracen-9,10-imines in nonreducing conditions. The iV-ethoxycarbonyl derivative (192) decomposed at 215° in cyclohexane to 33% of 205, although curiously this product was not obtained if the solvent was previously degassed. Whether or not the reaction involves simple extrusion of ethoxycarbonyl nitrene could not be established, since the expected iV-cyclohexylurethane was not detected. The 9,10-epithioanthracene (194) loses sulfur thermally to give 205.  

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Use has been made of the C-N cleavage in the conversion of the bicyclic tertiary amines, derived from the 4tc + 2tc cycloaddition of pyrroles and isoindoles with benzynes, into aromatic systems, e.g. naphthalen-l,4-imines and anthracen-9,10-imines yield naphthalenes and anthracenes with the extrusion of the nitrogen bridge [24] in yields which are higher than those obtained by standard oxidation procedures. 

Azabicyclo[2.2.i]hepta-2,5-dienes, Naphthalen-1,4-imines, and Anthracen-9,io-imines... 

In the 7-azabicyclo[2.2.1]heptadiene series there is as yet no instance known of aromatization by deamination such as occurs with some naphthalen-l,4-imine and anthracen-9,10-imine derivatives (see Sections III, H and IV, D). On the other hand, a close parallel exists between those reactions and some instances of aromatization of bicyclo[2.2.1] structures by loss of a heavier heteroatom from the 7-position, e.g., 70 71. 1,2,3,4,5-Pentaphenylphosphole reacts with dimethyl acetyl-... 

The formation of anthracene in reactions of 185 and 186 with benzyne, which was unexplained by Wittig et aZ., possibly is due to an alternative reaction of the intermediate zwitterion (202) with another molecule of benzjme or with a benzyne precursor. Benzyne reacted with the isoindole (206) to give the tetramethyltriptycene (208) and, in a separate run using excess of the benzyne precursor, W-benzylcarbazole. The latter product would appear to be made up of the iV-benzyl group from an intermediate anthracen-9,10-imine (207) and two molecules of benzyne. Mass spectral evidence also implicated the adduct 207, and the formation of 208 was attributed to benzyne-induced deamination of 207 to 1,4,9,10-tetramethylanthracene, which was trapped by further addition of benzyne across the 9- and 10-positions. 

In a related reaction (see also Section III, H) the anthracen-9,10-imine (187) with dimethyl acetylenedicarboxylate at 180° gave 26% 1,4-dimethyl-9,10-diphenylanthracene (209) and 14% of its Diels-Alder adduct with the acetylenic ester, the 9,10-ethenoanthracene (210). No nitrogen-containing product was isolated, and the related compounds 188 and 189 failed to react with the acetylenic ester. 

Thiazines heve been synthesized from the nitrile imine dimer 300 (Equation 105) <1980J(P1)2923>, 1,4-dithiin 1,1,4,4-tetraoxide 301 (Equation 106) <1982TL299>, 1,4-oxathiins (Equation 107) <1996JOC3894>, and the anthracene adduct 302 (Scheme 77) <1998S915>. 

An interesting deamination of naphthalene- 1,4-imine 169 and anthracene-9,10-imine with PTC-generated dichlorocarbene was reported in 1981.265... 

Nitrogen-Bridged Six-Membered Ring Systems 7-Azabicyclo[2.2.l]hepta-2,5-dienes, Naphthalen-l,4-imines, and Anthracen-9,10-imines L. J. Kricka and J. M. Vernon, Adv. Heterocycl. Chem., 1974,16, 87-122. 

Rhodium(II) acetate catalyzes C—H insertion, olefin addition, heteroatom-H insertion, and ylide formation of a-diazocarbonyls via a rhodium carbenoid species (144—147). Intramolecular cyclopentane formation via C—H insertion occurs with retention of stereochemistry (143). Chiral rhodium (TT) carboxamides catalyze enantioselective cyclopropanation and intramolecular C—N insertions of CC-diazoketones (148). Other reactions catalyzed by rhodium complexes include double-bond migration (140), hydrogenation of aromatic aldehydes and ketones to hydrocarbons (150), homologation of esters (151), carbonylation of formaldehyde (152) and amines (140), reductive carbonylation of dimethyl ether or methyl acetate to 1,1-diacetoxy ethane (153), decarbonylation of aldehydes (140), water gas shift reaction (69,154), C—C skeletal rearrangements (132,140), oxidation of olefins to ketones (155) and aldehydes (156), and oxidation of substituted anthracenes to anthraquinones (157). Rhodium-catalyzed hydrosilation of olefins, alkynes, carbonyls, alcohols, and imines is facile and may also be accomplished enantioselectively (140). Rhodium complexes are moderately active alkene and alkyne polymerization catalysts (140). In some cases polymer-supported versions of homogeneous rhodium catalysts have improved activity, compared to their homogenous counterparts. This is the case for the conversion of alkenes direcdy to alcohols under oxo conditions by rhodium—amine polymer catalysts... 

Based on this sequence, Blum et a/.158 have reported a general synthesis of unsubstituted K-region arene imines from the corresponding arene oxides. K-Imines of benz[a] anthracene, 7-methylbenz[a]anthracene, dibenz [a,/i] anthracene, and benzo[a] pyrene have been prepared. Azido alcohol formation from these oxides is generally nonregiospecific and both possible regioisomers of the azido alcohols are formed in different proportions. 

The same authors reported the synthesis of 6-substituted phenanthridines 360 via intramolecular trapping of imine anions 359179b. They speculated that these two observations could lead to the pentacyclic systems 361a-c from 358a-c via the cascade process indicated in Scheme 109. They also reported that compounds 358 could be converted into pentacyclic 13-azadibenzo[a, [Pg.130]

An efficient 1,3-dipolar cycloaddition has been developed to prepare 2,3-dihydro-[l,3,4]selenadiazoles 233 <07TL2302>. The reaction involves selenoaldehyde-anthracene adduct 230 and hydrozonyl chloride 231 in refluxing toluene. The [2+3] cycloaddition of reactive selenoaldehydes 229 (generated from 230 via thermal retro Diels -Alder) and nitrile imine 232 (created via dehydrochlorination of 231 with triethylamine) allows the formation of dihydro-[l,3,4]selenadiazole 233 as a single regiomer. 

A further step in the development of fluorescent sensors based on [Zn (tren)] + and anthracene fragments is the construction of a cage-shaped host. For example, 44 can be obtained by reacting the ligand 43 with two equivalents of terephtalal-dehyde and subsequent reduction of the four imine bonds of the Schiff base. 

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