Unexpected Catalyzed CC Bond Cleavage by Molecular Oxygen Promoted by a Thiyl Radical

Abstract

Olefin oxidation with molecular oxygen, promoted by a transition metal catalyst and a thiophenol, involved C=C bond cleavage into the corresponding carbonyl derivatives. This new reaction proceeds under one atmosphere of oxygen, at room temperature, in the presence of an excess of thiophenol and a catalyst such as MnL(2) 3a or VClL(2) 3c. It was applied to aromatic and aliphatic olefins, as well as to functionalized or unfunctionalized acyclic compounds, providing the corresponding ketones and aldehydes in up to 98% yield. The synthetic interest of this catalytic oxidation was illustrated by a one-step preparation of the fragrance (-)-4-acetyl-1-methylcyclohexene 7e in 73% isolated yield. The C=C bond cleavage probably results from a catalyzed decomposition of the beta-hydroperoxysulfide intermediate 12 that is formed by the radical addition of thiophenol to the olefin in the presence of oxygen. Although an excess of the thiophenol was used, it was transformed into the disulfide which could then be reduced without purification in 83% overall yield, thereby allowing for recycling. In addition, the C=C bond cleavage under oxygen could be promoted by catalytic quantities of the thiyl radical, generated by photolysis of the disulfide; thus, in the presence of 0.1 equiv of bis(4-chlorophenyl) disulfide 4b and 5% of the manganese complex 3a, trans-methylstilbene 1b gave, under radiation, benzaldehyde 6a and acetophenone 7a in up to 95% yield. This new reaction offers an alternative to the classical C=C bond cleavage procedures, and further developments in the fields of bioinorganic and environmental chemistry are likely.

Ruthenium–Lewis Acid Catalyzed Asymmetric Diels–Alder Reactions between Dienes and α,β‐Unsaturated Ketones

“…Corey [20] had previously reported 22 in 80 % ee (87 % yield) and MacMillan [18] obtained 24 in 85 % ee (79 % yield) so here the Ru catalyst system outperforms the literature catalysts in terms of ee though the yields are lower. The absolute stereochemistry of the compounds in Table 2 have been reported previously (except 21); 23 has been prepared from (À)-limonene, [32] 22 was assigned by Corey [20] by analogy to 10 and MacMillan [18] prepared an authentic sample of 24 from the corresponding chiral aldehyde.…”

Disulfide‐Catalyzed Visible‐Light‐Mediated Oxidative Cleavage of C=C Bonds and Evidence of an Olefin–Disulfide Charge‐Transfer Complex

“…Recently, photochemical OCO methods have been reported with the photon as a traceless reagent and a green source of energy. [8][9][10][11][12] In general, these methods required UV-light, or catalysts that are toxic [8] or metal-based, [9] or a demandingly oxidative photoredox catalyst to be SET-reduced by the olefin. [10][11][12] Alternatively, it would be attractive to seek a nonmetal photocatalyst that functions via a non-redox/sensitization mechanism, and preferably with a reduced cost than most photocatalysts.…”

Fe(III) complex anchored SBA-15 is a new heterogeneous catalyst for the cleavage of aliphatic CC bond of styrene and its derivatives

“…However, high selectivity of benzaldehyde has been reported by few authors [25][26][27][28] with certain demerits. Baucherel et al [25] reported the unexpected high selectivity towards the C@C cleavage of olefins in the presence of molecular oxygen with Mn-salen with thionyl radical promoter, but the used catalyst is homogeneous, and in addition, mixing of thionyl radical and H 3 PO 4 are the drawbacks of this system. As a safety alternative to ozonolysis, Miyamoto et al [58] developed an efficient method for C@C bond cleavage with high yields of aldehydes, using a combination of iodosylbenzene and HBF 4 in the presence of water, but this method is also homogeneous in nature.…”

“…Over-oxidation of aldehyde to the corresponding acid as side-reaction is in most cases unavoidable. Despite mild and selective oxidation methods gaining increased importance, only few novel or improved methods for cleavage of C@C bond of alkenes are available [25][26][27][28]. Therefore, the development of inexpensive, selective, safe and environmentally friendly procedure for the cleavage of C@C bonds is highly desirable.…”