Coupled reductions

In 2-propanoI, the quantum yield for photolytic conversion of benzophenone to the coupled reduction product is 2.0. The reason is that the radical remaining after abstraction of a hydrogen atom from 2-propanol transfers a hydrogen atom to ground-state benzophenone in a nonphotochemical reaction. Because of this process, two molecules of benzophenone are reduced for each one that is photoexcited ... 

Bacteria can use a range of electron acceptors in the absence of oxygen. Although they are able to reduce a number of oxyanions, only a limited number of these can support growth under anaerobic conditions by coupling reduction to the production of energy by proton translocation. A number... 

Vinyl Ketone-C=X (X=0, NR) Coupling (Reductive Aldol and Mannich Additions)... 

The phenanthrene 1,2- and 3,4-diones are synthetically accessible from the related 8 phenols. Oxidation of 2-phenanthrol with either Fremy s salt ((KS0 )2N0) or phenylseleninic anhydride gave phenanthrene 1,2-dione directly (55). Unexpectedly, oxidation of 3-phenanthrol with (KSOg NO yielded 2,2-dihydroxybenz(e)indan-l,3-d-ione (Figure 10). However, phenanthrene 3,4-dione was readily obtained from 3-phenanthrol by Fieser s method entailing diazonium coupling, reduction, and oxidation of the resulting 4-amino-3-phen-anthrol with chromic acid (56). 

Beunink J, Rehm HJ (1990) Coupled reductive and oxidative degradation of 4-chloro-2-nitrophenol by a co-immobilized mixed culture system. Appl Microbiol Biotechnol 34 108-115... 

An additional path to protonation of coordinated NO is the reduction of the M-NO unit electrochemically (73). Such coupled reduction/proto-nation schemes have been argued to be relevant to enzymatic nitrogen oxide reductases (41). Farmer and coworkers (74) accomplished such reductions by using graphite electrodes modified by depositing... 

An interesting, peculiar laboratory preparative reaction may finally be mentioned. This is based on the very high stability of the intermetallic compounds of actinides (and lanthanides) with the platinum family metals. The combined reduction capability of Pt with H2 (coupled reduction, see 6.7.2 fi) can be used to obtain, from its oxide, the platinide of the actinide metal. The An-Pt intermetallic compound can then be decomposed by heating in vacuum and the actinide can be obtained by distillation. 

Coupled reduction with platinum group metals. Very pure metals of the alkaline earth, lanthanide and actinide series can be prepared from their oxides (or fluorides) by coupled reduction by pure hydrogen in presence of platinum group metals (see 6.7.2.2). 

Preparation of base metals by coupled reduction with platinum group metals. Very pure metals of the alkaline- earth, lanthanide and actinide series can be prepared from their oxides (or fluorides) through coupled reduction by pure hydrogen in presence of platinum group metals. According to a precursory paper on this subject (Berndt et al. 1974), the preparation scheme of Li, Ca, Sr, Ba, Am and Cf was described. As an example, Ca can be obtained by synthesis of a Pt compound, followed by its vacuum decomposition and recovery by distillation of the more volatile base metal ... 

Clostridium sticklandii also expresses a proline reductase that can reduc-tively cleave proline to 8-aminovalerate (Seto and Stadtman 1976). PR was first purified by Seto and Stadtman (1976) by following the decomposition of proUne in the presence of dithiothreitol or NADH. They found PR to have a denatured mass of approximately 30kDa (sodium dodecyl sulfate-polyacrylomide gel electrophoresis SDS-PAGE) and a native size of approximately 300 kDa. The addition of selenite to the growth medium of C sticklandii did increase the specific activity of PR in extracts by threefold however, no selenium was detected in the purified enzyme. It should be noted that this purified enzyme had lost the ability to couple reduction of proline to NADH and thus probably was missing one or more components of the complete enzyme complex. 

Rapoport, S.I. (2003) Coupled reductions in brain oxidative phosphorylation and synaptic function can be quantified and staged in the course of Alzheimer disease. Neurotox. Res., 5, 385-398. 

Coupling, reductive, of o-chlorobenzal-dehyde by hexamethylphosphor-ous triamide to give 2,2 -di-chloro-a,a -epoxybibenzyl, 46, 31, -Cresol, 48, 96 -t-Crotonolactone, 46,22 Crotyl diazoacetate, 49, 22, 24 Cupric acetate in coupling of phenyl-acetylene, 46, 39... 

The compounds with elements of the platinum group can be prepared by direct synthesis, which requires the availabiUty of actinide metals. Such intermetallics can, however, also be obtained by coupled reduction of actinide oxides with hydrogen in the presence of finely divided noble metals ... 

The bicyclic ketone (44), obtained from the Fe2(CO)9-promoted [3 + 4] cycloaddition reaction of a,a,a, a -tetrabromoacetone and 2-isopropylfuran followed by Zn-Cu couple reduction, has been converted to the naturally occurring troponoid, /3-thujaplicin (46) (75JOC806). Hydrogenation of (44), ether cleavage, bromination and dehydrobromination gave the tropone (45), an intermediate easily converted into the tropolone (46) by a standard procedure (Scheme 10). A related [3 + 4] cycloaddition reaction of oxyallyl metallic with furan has been used to assemble the antibiotic C-nucleosides (78JA2561). 

Of all the hydrocarbon derivatives of [60]fullerene, C60H2, first prepared by Henderson and Cahill using a hydroboration-hydrolysis procedure, is the simplest. Multiple other methods have been demonstrated for the formation of C60H2 including two (i.e., a NaBH4 reduction and a Zn(Cu) couple reduction) that produce C60H2 in good isolated yield. 

Fig. 6.4 Zn(Cu) couple reduction of [60]fullerene produces three isomers of and three isomers of Ca)H6 including 1,2,33,41,42,50-C H that has been isolated...

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