In situ PHIP‐NMR studies during the stereoselective hydrogenation of sorbic acid with a [CpRu] catalyst

Development of new methods in modern selective organic synthesis: preparation of functionalized molecules with atomic precision

“…For conjugated dienes, this can be used to identify processes such as 1,4-addition. 652 In the hydrogenation of styrene catalyzed by some cationic rhodium complexes, polarized ethylbenzene formed in the reaction was observed not only in the free state in solution but also being Z 6 -coordinated to rhodium(I). 653,654 The PHIP effect can also serve to enhance the NMR signals of short-lived intermediates and thus to establish their structure and the role in the reaction mechanism (Fig.…”

One-step and non-catalytic intramolecular redox reactions of conjugated all E-dienals to non-conjugated Z-enoic acids in subcritical water

“…For conjugated ketone derivatives such as (2E,4E)-1,5-diphenylpenta-2,4-dien-1-one (6) and (3E,5E)-6-methylhepta-3,5-dien-2-one (10), however, a remarkable difference in reaction behavior was observed to continuously produce retro-aldol products cinnamaldehyde (7), acetophenone (8), benzaldehyde (9), and 3-methylbut-2-enal (11) in addition to a cyclization product, m-xylene (12). Judging from these results, the aldehyde group is indispensable for the intramolecular redox reactions and the cyclization.…”

“…Hydrogenation of sorbic acid catalyzed by Cr(CO) 6 [11] or [Cp*Ru] + [12,13], which fixes two double bonds of sorbic acid to s-cis conformation in the metal center, is a typical method. The classical P-2 Ni catalyst is also available through the hydrogenation of unsaturated acid bearing a triple bond [4,5].…”

Homogeneous Hydrogenation of Alkynes and Dienes

“…In general, the hydrogenation of sorbic alcohol proceeds with higher activity and almost complete selectivity when using 52 as the catalyst. Mechanistic studies employing the PHIP phenomenon showed that the homogeneous hydrogenation of sorbic acid (in acetone under 1 bar H 2 ) proceeds by concerted 1,4-hydrogenation of the diene moiety [68]. Both atoms of the same dihydrogen molecule are transferred to the substrate in a synchronous fashion, yielding cis-3-hexenoic acid as the primary reaction product.…”