Merging C–H and C–C bond cleavage in organic synthesis

Metal‐Catalyzed Remote Functionalization of ω‐Ene Unsaturated Ethers: Towards Functionalized Vinyl Species

“…This alternative strategy, coined remote functionalization, has therefore attracted considerable attention as it allows carbon–carbon bond‐forming events at nonclassical positions (Scheme a) . Among several possibilities to address this issue, the ability of a transition‐metal complex to undergo a rapid “metal‐walk” along a hydrocarbon chain to functionalize the terminus position has proven to be a valuable strategy to build molecular complexity (Scheme b) . In this context, we reported the zirconocene‐mediated transformation of unsaturated fatty‐acid alcohol derivatives ( 1 ), through successive allylic C−H bond activations followed by an irreversible β‐alkoxide elimination reaction, into substituted allylzirconocene species ( 2 ; Scheme c) .…”

“…We then extended this concept to the selective preparation of stereodefined dienylzirconocene species ( 4 ) from ω‐ene enol ether derivatives ( 3 ), and to the acyclic bifunctionalized products 6 through a combined zirconium chain walk and selective ring opening of ω‐ene cyclopropanes ( 5 ) . Outstanding catalytic processes, based on Pd, Ni, Ru, Rh, Ir, and Co complexes promoting rapid isomerization across hydrocarbon chains, have been also developed, thus allowing the design of various valuable synthetic transformations . However, an important transformation that was missing in the arsenal of remote activations until this work and the work of Mazet and co‐workers was the preparation of a distant vinyl metal species from a simple ether possessing a remote double bond (Scheme d) that could subsequently undergo various functionalization to provide functionalized alkenes ( 10 ).…”

The definitive challenge of forming uncommon pseudo‐π···H–F and C···H–F hydrogen bonds on cyclic and cubic nonpolar hydrocarbons

“…Moreover, other cycloalkanes are also submitted to the same ring-opening reaction process, as is the case of the cyclobutane (see initial step 2a). [64,65] With regard to the hydrogen bond conception, however, the regioselective attack of the hydrogen fluoride towards the carbons might result in a linked structure (2b 0 ) through a hydrogen bond in the form of CÁÁÁH-F. Ideally, Grabowski [66] has demonstrated the occurrence of the CÁÁÁH-F hydrogen bond in complexes formed by hydrogen fluoride and cyclobutane.…”

Metal‐Catalyzed Remote Functionalization of ω‐Ene Unsaturated Ethers: Towards Functionalized Vinyl Species

“…[6] Outstanding catalytic processes,b ased on Pd, [7] Ni, [8] Ru, [9] Rh, [10] Ir, [11] and Co [12] complexes promoting rapid isomerization across hydrocarbon chains, have been also developed, thus allowing the design of various valuable synthetic transformations. [2,3] However,a ni mportant transformation that was missing in the arsenal of remote activations until this work and the work of Mazet and coworkers [13] was the preparation of adistant vinyl metal species from as imple ether possessing ar emote double bond (Scheme 1d)t hat could subsequently undergo various functionalization to provide functionalized alkenes (10). Our proposed strategy would rely on the in situ transformation of the w-alkenyl ether 7 into the enol ether 8 by am etal-catalyzed migration of the double bond.…”

“…[2] Among several possibilities to address this issue,t he ability of at ransition-metal complex to undergo ar apid "metal-walk" along ah ydrocarbon chain to functionalize the terminus position has proven to be av aluable strategy to build molecular complexity (Scheme 1b). [3] In this context, we reported the zirconocene-mediated transformation of unsaturated fattyacid alcohol derivatives (1), through successive allylic CÀH bond activations followed by an irreversible b-alkoxide elimination reaction, into substituted allylzirconocene species (2;S cheme 1c). [4] We then extended this concept to the selective preparation of stereodefined dienylzirconocene species (4)f rom w-ene enol ether derivatives (3), [5] and to the acyclic bifunctionalized products 6 through ac ombined zirconium chain walk and selective ring opening of w-ene cyclopropanes (5).…”