Ruthenium-Catalyzed 1,3-Aryl Redox Isomerization of Allylic Alcohols

Abstract

The isomerization of allylic alcohols to the corresponding carbonyl compounds is a well-established reaction in organic synthesis. However, 1,3-carbon migration is a quite challenging field, and thus transformation has remained elusive until now. Herein, we present the ruthenium-catalyzed intramolecular 1,3-aryl migrative isomerization, which provides a mild and environmentally friendly method to synthesize various ketones with high step-and atom-economy and broad substrate scope. Meanwhile, the Ru(III)-catalyzed C(sp 3 )−C(aryl) bond cleavage of unactivated allylic alcohols may serve as a heuristic paradigm for transition-metal-catalyzed C−C activation.

Manganese‐Mediated Reductive Alkylation of Thiazolyl‐Phosphonium Salts

“…A control experiment, performed with thiazolyl‐phosphonium salt ( 7 a ) and benzyl bromide ( 8 a ) in the absence of commercial Mn 0 yielded none of the product ( 9 a ), showing that the elemental manganese was essential (Scheme 3a). Radical trapping experiments with TEMPO gave no product and BHT had no effect on the reaction, implying that a radical process is not involved in the transformation (Scheme 3b) [22] . Although the detailed mechanism remains unclear, a tentative hypothesis was proposed and is shown in Scheme 3c.…”

“…Radical trapping experiments with TEMPO gave no product and BHT had no effect on the reaction, implying that a radical process is not involved in the transformation (Scheme 3b). [22] Although the detailed mechanism remains unclear, a tentative hypothesis was proposed and is shown in Scheme 3c. First, Mn 0 undergoes oxidative addition with benzyl bromide (8) to furnish an organomanganese intermediate (I).…”

Ruthenium-catalyzed 1,3-indolyl migration within α,α-disubstituted allylic alcohols

“…Recently, our group achieved an intramolecular aryl migration catalyzed by a ruthenium complex, 11 which gave rise to a series of ketones under mild conditions. As a further application of this protocol, we herein disclose a ruthenium-catalyzed 1,3-indolyl migration within allylic alcohols.…”

“…9 Although 1,3-carbon migration has witnessed such progress, selective C(sp 3 )-C(sp 2 ) bond cleavage is still a challenge in this field. 10 Recently, our group achieved an intramolecular aryl migration catalyzed by a ruthenium complex, 11 which gave rise to a series of ketones under mild conditions. As a further application of this protocol, we herein disclose a rutheniumcatalyzed 1,3-indolyl migration within allylic alcohols.…”

Rh-Catalyzed Intramolecular Hydroarylation of Unactivated Alkenes via C–C Bond Activation

“…Although attractive, the C–C bond activation has always been challenging due to its high stability. Encouragingly, significant progress has been made in the transition-metal-catalyzed C–C bond activation of tertiary alcohols via β-C elimination of the in situ formed alcoholate intermediates, which are greatly driven by the release of ring strain or the formation of relatively stable organometallic species . As an important type of small-membered alcohols, benzocyclobutenol has found wide applications in organic synthesis through the opening of a strained ring.…”