Acenaphthylene reduction

Double bonds conjugated with benzene rings are reduced electrolytically [344] (p. 23). Where applicable, stereochemistry can be influenced by using either catalytic hydrogenation or dissolving metal reduction [401] (p. 24). Indene was converted to indane by sodium in liquid ammonia in 85% yield [402] and acenaphthylene to acenaphthene in 85% yield by reduction with lithium aluminum hydride in carbitol at 100° [403], Since the benzene ring is not inert toward alkali metals, nuclear reduction may accompany reduction of the double bond. Styrene treated with lithium in methylamine afforded 25% of 1-ethylcyclohexene and 18% of ethylcyclohexane [404]. 

A major group of photochemical reduction reactions are oxidation-reduction processes. As typical examples, phenazine (CXXI) and alloxan (CXXIII) are reduced by ethanol to give dihydrophenazine (CXXIl)/ 2 and alloxantin (CXXIV).42 Isatin (CXXV) in the presence of ace-naphthene (CXXVI) is reduced to isatide (CXXVII).204 The photoreaction proceeds at the expense of the alcohol, or (CXXVI) acetaldehyde and acenaphthylene (CXXVIII), are formed as by-products respectively. The formation of CXXVII may be due to the interaction of CXXV with the intermediate oxindole (CXXIX). 

Related complexes of group 10 metals are accessible by an oxidative addition/reductive cyclization protocol, exploiting the inverse electron demand (Scheme 27) (Pt <2005JA13494>, Ni <20030M3604>). The nickel complex is thermally unstable, proceeding to perylene via a bimolecular reductive elimination or, in the presence of alkynes, delivering acenaphthylene derivatives by an insertion/reductive elimination pathway. 

Acenaphthylene dibromide (147) was also reduced to produce acenaphthylene (148) in quantitative yield (equation 85). A similar result was reported by Inesi and collaborators129, and confirmed again by others130. Four-electron reduction of ortho-xylylene tetra-bromide (149) gives the same stable product, 146, deduced to arise from benzocyclo-butadiene following a [4+2] cycloaddition and retro[2+2] rearrangement to rearomatize. 

The rednctive conpling (see Reductive Coupling) of acenaphthylene by activated metallic ytterbium and samarium yields unra-lanthanidocenes [( ) -Ci2H8)2Ln(THF)2] (Ln = Yb, Sm) (equation 25). 

It was recognized that acenaphthene 40 and acenaphthylene 107 proton sponges, unlike the pair of compounds 11 and 124, easily interconvert by oxidation and reduction, respectively38. Since in the course of this transformation, the basicity change amounts to over four plsfa units (equation 11), these compounds form a redox system with easily modified basicity. It is believed that such properties may be of use in creating molecular devices38. 

The same compounds are also readily accessible via reductive coupling of acenaphthylene with activated ytterbium or samarium as depicted in Scheme 151.626>626 ... 

The spectroscopic studies 83,84) afforded chemical applications. The reductive alkylation of dianion 82 gave alkylated products only in the periphery121K This observation confirms the structure So2 suggested by Rabinovitz and Hafner 84b). Contrary to the reductive alkylation of 232 the quench of dianion 82 did not afford any alkylated product at the central atom C-l 1. The alkylated acenaphthylene served as a starting material for the preparation of acephenanthrylene 34z (vide supra)121). 

The higher homologs of acenaphthylene dianion 82 are the aceanthrylene dianion 33 and acephenanthrylene dianion 34 122,123). The convenient synthesis of the the hydrocarbon enabled a detailed investigation of their metal reduction and the exploration of their patterns of delocalization. Despite their being (4n + 2)ji-electron systems, these anions are not diatropic as one may expect from counting their jc-electrons. 

Under conditions of reductive silylation, acenaphthylene (252) can be converted into l,2-bis(TMS)-acenaphthene (253) by means of either Me3SiCl/Mg/HMPA (yield 81%)... 

The acenaphthylene column (second compound from the left) is blank because its analytical values were usually too low to be determinate. 2-Methylnaphthalene (rightmost column) is slightly positive, indicating an increase. The analysis shows an overall 17.3% reduction (test vs. control) in total PAHs. The thee-ring com-... 

There is another type of microflow cell that is used for electrolyte-free electrolysis [64]. Two carbon fiber electrodes are separated by a spacer (porous PTFE membrane, pore size 3 pm, thickness 75 pm) at a distance of the order of micrometers. A substrate solution is fed into the anodic chamber where the oxidation takes place. The anodic solution flows through the spacer membrane into the cathodic chamber where the reduction takes place. The product solution leaves the cell from the cathodic chamber. In this cell, the electric current flow and the liquid flow are parallel. The effectiveness of the cell is shown by the oxidation of p-methoxytoluene. A solution of p-methoxytoluene in methanol is fed into the electrochemical microflow system and the reaction is carried out under constant current conditions to obtain the desired product in more than 90% yield based on consumed starting material (Figure 7.8). The microflow system can also be used for the oxidative methoxylation of N-methoxycarbonylpyrrolidine and acenaphthylene. 

FIGURE 2.34 Reduction of acenaphthylene (concentration 5 mmol.L ) in superdry DMF + 0.1 molL M TBABF4 added with 7.5 mmol.L" Nal. Potentials are referred to the SCE electrode. Scan rate 0.1 V s". (a) Voltammetry at a platinum microelectrode, (b) EQCM experiment at gold film quartz covered by platinum. Experimental conditions are strictly the same for (a) and (b) (Simonet, J., Unpublished results). 

L. Wang, W. Wang, 1. Cuui, W. Ren, N. Meng, 1. Wang, X. Qian, Preparation of chiral trans-5-substituted-acenaphthene-l,2-diols by Baker s yeast-mediated reduction of 5-substituted-acenaphthylene-l,2-diones. Tetrahedron Asymm. 21 (2010) 825-830. 

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