Benzophenone azine, reduction

In the same study, a one-pot variant avoiding the isolation of the intermediate hydrazone was attempted. However, reduction of the crude hydrazone leads to the formation of by-products for example, in the reaction of benzophenone, a mixture of diphenylmethane and benzophenone azine was found (Scheme 4.38)64. 

Another interesting uranium(rv) system is the bis-ketimido complex, Cp 2U( N=CPh2)2, formed via the reduction of Cp 2UCl2 in ether with 2 mol of potassium graphite (KCg) in the presence of benzophenone azine, Ph2C=N N=CPh2. The molecular structure is depicted in (6)." ... 

As mentioned previously, DMSO as the reaction medium provides significant enhancement of Wolff-Kishner reaction rates and this allows the use of much lower temperatures to effect reductions. In 1962 Cram et al. introduced the use of r-butoxide in dry DMSO for the successful reduction of preformed hydrazones at room temperature. Using this process, benzophenone hydrazone (15) afforded an 88% yield of diphenylmethane (16), along with 11% of benzophenone azine (17) as side product (equation 5). However, maximum success requires very slow addition (i.e. over 8 h) of the hydrazone to the reaction solution, otherwise yields of reduced products are decreased and azine formation augmented. Thus, addition of (15) over 0.5 h in the above reaction lowered the yield of (16) to 72%, while the yield of (17) was increased to 22%. - Other successful reductions reported - include hydrazones of benzaldehyde (67%), camphor (64%) and cyclohexanone (80%). 

Reaction of [Sm(Tp )2] with fluorenone, benzophenone, benzalde-hyde azine, and phenantrenequinone gives monomeric [Sm(Tp )2X]. Reaction of [Sm(Tp )2] with less bulky ligands such as benzaldehyde or pyrazine leads to dimetallic [Sm(Tp )2]2[R-Y] (Y = dianion formed by C-C coupling of two reductively eliminated ligands).628... 

---