Reductive elimination photoinduced

Successive hydrogen transfers within 60, followed by coordination of olefin and then H2 (an unsaturate route), constitute the catalytic cycle, while isomerization is effected through HFe(CO)3(7r-allyl) formed from 59. Loss of H2 from 60 was also considered to be photoinduced, and several hydrides, including neutral and cationic dihydrides of iridium(III) (385, 450, 451), ruthenium(II) (452) and a bis(7j-cyclopentadienyltungsten) dihydride (453), have been shown to undergo such reductive elimination of hydrogen. Photoassisted oxidative addition of H2 has also been dem-... 

Photoinduced reductive elimination of from polyhydride complexes, HxMLn (x > 3) can, in principle, lead to the generation... 

Platinum-carbon bond cleavage can be photoinduced. The photoinduced reductive elimination of cyanoalkanes from ftwis-PtH(R)(PPh3)2 (R = CH2CN, (CH2)2CN, (CH2)3CN) involves initial isomerization to the cis isomer prior to reductive elimination.563 Photolysis of platinacyclopentanes gives alkanes and alkenes.564... 

The above results suggest that the metallacyclobutane complexes 48-51 have at least two photodecomposition pathways available to them (1) r -r shift of the Cp rings with homolysis of one of the metal-carbon bonds, and (2) possibly a concerted, photoinduced reductive-elimination reaction for the formation of cyclopropylbenzene from 51 [Eq. (63)]. 

For the thorium cyclopentadienyls with R = CH3, photolysis in aromatic solvents produces 1 1 mixtures of alkene and alkanes and the trivalent thorium complex Th(C5E5)s. It was proposed that the reaction takes place by a photoinduced beta-elimination to give a hydrido complex and olefin followed by a bimolecular reductive elimination of the alkane. Schematically it can be represented by the following equations ... 

Photoinduced reductive elimination of is synthetically important because it can lead to the generation of reactive organometallic complexes not obtained under thermal conditions, e.g., in the photochemistry " of (h -C5H5)jWH2, which leads to the smooth elimination of Hj and generation of tungstenocene, (h -C5H5>jW ... 

Table 1. Photoinduced Reductive Elimination of from Di- AND Polyhydride Complexes ...

The reaction is an example of a photoinduced intramolecular reductive elimination reaction. No intermediates could be detected during this transformation. 

The photoinduced reductive elimination of hydrogen occurs by a concerted / reaction rather than by a stepwise sequence. This concerted pathway is supported by the experimental observation that photolysis of a solution containing a mixture of IrClH2(PPh3)3 and IrClD2(PPh3)3 gave only H2 and D2, with no formation of the crossover product Several explanations have been offered for the photoin-... 

Organometallic hydride complexes, like those of other transition metal complexes, undergo photochemical reactions. Organometallic hydrides are known that contain either a single M-H bond, or two bonds to hydrogen in complexes of type MH2. A common reaction of the latter type is the photoinduced reductive elimination of hydrogen ... 

The photoinduced reductive elimination of cyanoalkanes from complexes such as frans-[PtH(CH2CN)(PPh3)2l proceeds through the cis isomer, reaction (143) and incidentally provides a useful way of forming [Pt(PPh3)2]/ ... 

These systems use BLs that provide intercomponent coupling and a photoreactive rhodium dihydride system. The authors demonstrated that these complexes undergo photoinduced reductive elimination of hydrogen when irradiated at wavelengths < 436 nm (Fig. 10). ... 

FIGURE 10. Representation of photoinduced reductive elimination of hydrogen by [(bpy)2Ru(dpp)RhH2(PPh3)2] (bpy = 2,2 -bipyridine, dpp = 2,3-bis(2-pyridy])pyrazine). 

With intermediate 60 in hand, a key photoinduced HBr elimination furnished the second 12-membered ring and provided intermediate 61. After reductive removal of the spectator phenol through its triflate, selective acylation, indole C-2 chlorination, and treatment with tris(dimethylamino)sulfur trimethyldifluorosilicate, afforded the desbromo diazonamide B (62). Finally, phosphoryl cyanide-mediated condensation with commercial (5)-ot-hydroxyisovaleric acid delivered (-)-diazona-mide A (47) (Scheme 9). 

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