Transition Metal-Mediated [3 + 2 + 2] Allyl/Alkyne Cycloaddition Reactions. A New Reactivity Pattern for the Synthesis of Seven-Membered Carbocycles

Abstract

The investigation of transition metal-mediated allyllalkyne coupling reactions has revealed a range of synthetically valuable' or potentially e~p l o i t a b l e~.~ reactivity pattems. Particularly interesting are the q3-allyllalkyne cyclization reactions reported by Rubezhov, assembling the q5-cyclopentadieny13a and 7' ,r4-methanocy~lohexadiene~~ ring systems by incorporation of one or two alkyne equivalents, respectively. In this communication, we report a new reactivity pattem on this energy surface: sevenmembered-ring synthesis via metal-mediated [3 + 2 + 21 cycloaddition, coupling an q3-allyl ligand with two alkynes to yield the q5-cycloheptadienyl ring system (eq 1). Eq. 1Treatment of q3-allyl 2-butyne complex 2a, prepared as previously described or generated in situ from triflate complex 1: with diphenylacetylene leads to the formation of the tetrasubstituted q5-cycloheptadienyl complex 35 in 56% yield, (1) Cyclization or linear coupling of allyl and alkyne ligands. (a) Chuisoli reaction and related Ni "metalla-ene" processes: Chiusoli, G. P.

Synthesis and Reactivity of Ir(CO)(η2-C2R2)(η5-C9H7) (R = Ph, Tol). Alkyne Coupling and Arene C−H Bond Activation Forming a Substituted Butadiene Ligand

“…Intermediates similar to D have been suggested for the reactions of [Ir(η 2 -MeC 2 Me)(η 3 -C 3 H 3 )(η 5 -C 5 Me 5 ) + ] with alkynes, in which the coupling of the allyl ligand and two alkyne units led to compounds containing η 5 -cycloheptadienyl ligands …”

Transition‐Metal‐Catalyzed [3+2+2] Cycloaddition Reactions

“…Different researchers have successfully explored functionalized cyclopropanes as 3π components with various alkenes, alkynes, diynes, among others, as 2π components in [3+2+2] cycloaddition reactions using Ni, Pd, Rh and Ru metal complexes as catalysts . The present review summarizes various reports on [3+2+2] cycloaddition reactions with not only products arising from the activity of the key players (different metal complexes) but also those from proton‐based chemistry for the synthesis of mono‐and/or condensed cycloheptadiene derivatives, since 2000.…”

Seven‐Membered Rings by Cyclization at Transition Metals: [4+3], [3+2+2], [5+2]

“…The reactions gave reasonable yields of 40-78 %; the reaction of 8 with deca-2,8-diyne (9) to give 10 was particularly successful, with a yield of 94 % (Scheme 2). [28] Further investigations with the cheaper catalyst metal cobalt showed that (h 3 -allyl)(h 5 -pentamethylcyclopentadienyl)-cobalt(III) triflates, such as 11, allow the formation of cycloheptatrienyl complexes like 13 by reaction with ethyne (12) or other terminal alkynes, when noncoordinating solvents such as dichloromethane were applied (Scheme 2). The cycloheptadienyl complexes thus obtained can be trapped Scheme 1.…”