Oxidation formal

The other important type of reaction leading to the formation of two bonds between a metal and four-atom fragment is addition of carbenoids, i.e. germylenes and stannylenes, to a-dicarbonyl and related compounds. The process can be classified as redox (4 + 1) cycloaddition since the dicarbonyl fragment is reduced while the carbenoid is oxidized. Formally the simplest example of such reactions is the interaction of methylglyoxal with activated tin metal to give a cyclic stannylene, Sn(II) enediolate (see Scheme 34) <83CL1825>. 

Addition-Oxidation Formal Nucleophilic Substitution for Hydrogen 531... 

Other substrates which reacted with cyanamide and DIB included sulphides, sulphoxides and phosphines [62]. In all these oxidations formally, but not actually, nitrenes are involved, which give the corresponding ylides. 

Next, let us examine the total built-in voltage developed across the oxide. Formally, we can write the total potential across the oxide as the sum of the potentials developed across the three zones... 

Another type of oxidative (formal) cycloaddition is exemplified by the oxidation of 1,3-diketones in MeCN in the presence of an olefin to di- or tetrahydrofuran derivatives [136] similar products may be obtained by reduction of 2,2-dibromo-1,3-diketones in the presence of an alkene [136]. 

Formal Charge In the discussion of several preceding molecules, including nitrous oxide, formal... 

However, a part of the vanadium (V) oxide is reduced to vanadium(IV) oxide formally. 

In this case the stoichiometry of oxidant uptake is one-half mole of X2 per metal ion rather than the one mole per metal ion that is characteristic of the monomeric analogs with the same metal ions. As a result, the metal ion is oxidized (formally) by one electron rather than by two electrons, and a metal-metal bond is formed. 

Scheme 7.93 NHC-catalyzed asymmetric oxidative formal [4 + 2] annulations of aliphatic aldehydes with a,p-unsaturated ketones or imines reported by Rovis.

Scheme 7.116 NHC-catalyzed oxidative formal [4 + 3] annulations between enals and azomethine imines reported by Chi.

In 2009, Jiang et al. reported that the oxidative formal [2- -2-1-1] cycloaddition of diarylalkynes 89 under an O2 atmosphere proceeds in the presence of Pd(OAc)2/Zn(OTf)2 catalyst to give tetraaryl-substituted furans 90 (Scheme 6.25) [37], They also developed the cross-[2 - - 2 - -1] cycloaddition of two different diarylalkynes 91 under an O2 atmosphere by using fluorous media (Scheme 6.26) [38]. 

In 2011, Lu et al. reported that the oxidative formal [2 + 2+1] cycloaddition of 1,8-dialkynylnaphthalenes 96 with primary amines 104 proceeds in dimethyl sulfoxide (DMSO) in the presence of PdCl2 catalyst and EtsN to afford fused pyrroles 98 (Scheme 6.27) [39]. In general, the use of aromatic amines afforded the corresponding pyrroles in higher yields than aliphatic amines. In this oxidative formal [2 + 2+1] cycloaddition, DMSO acts as an oxidant. 

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