Stabilization of Highly Electrophilic Allenes by Coordination with Manganese. Synthesis of 1-Functionalized Dicarbonyl (η-Methylcyclopentadienyl) (1-2η-3-Formylallene) Manganese Complexes.

Franck‐Neumann, M.; Neff, Denis; Nouali, Habiba; Martina, Daniel; Cian, André De

doi:10.1055/s-1994-22965

Cited by 13 publications

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“…The phosphorus atom is clearly away from the manganese atom, as indicated by the nonbonding distance Mn1···P1 of 4.693(1) Å. Trends in the metrical features are similar to those found in other manganese allene complexes. , In particular, the manganese-to-central carbon atom distance (Mn−C4 = 2.011(2) Å) is significantly shorter than the manganese-to-terminal carbon atom (Mn−C3 = 2.180(2) Å). The noncoordinated CC double bond (C4−C5 = 1.322(3) Å) compares reasonably well with those of the free allene molecules (1.307 Å), in contrast to the coordinated one, which is significantly elongated (1.407(3) Å).…”

Section: Resultssupporting

confidence: 59%

“…The principal outgrowth of the present report is to provide the first explicit evidence for the formation of allene complexes through such a route, thereby adding a new facet to the reactivity of alkynyl carbene complexes. Although the stability of Cp ( ′ ) (CO) 2 Mn(η 2 -allene) complexes might have been a priori regarded as a drawback for synthetic purposes, this is not the case, given that they are reactive enough to allow modifications of the coordinated allene ligand, , whereas the free allene may be released either by oxidation or, as shown in the present work, upon photolysis, thus giving new hopes for future development.…”

Section: Discussionmentioning

confidence: 84%

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Directed Formation of Allene Complexes upon Reaction of Non-heteroatom-Substituted Manganese Alkynyl Carbene Complexes with Nucleophiles

et al. 2008

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The non-heteroatom-substituted alkynyl carbene Cp′(CO) 2 MndC(Tol)CtCPh (1, Cp′ ≡ (η 5 -MeC 5 H 4 )) is first shown to react at low temperature with lithium diorganophosphide LiPR 2 (R ) Ph, Cy) to form an anionic species. Subsequent treatment with CF 3 SO 3 H affords the η 4 -vinylketene complex Cp′(CO) 2 Mn[η 4 -{R 2 P(Ph)CdCHC(Tol)dCdO}] (2; 2a: R ) Ph (70% yield), 2b: R ) Cy (55% yield)) as the major compound, along with trace amounts of the η 2 -allene complex syn-Cp′(CO) 2 Mn[η 2 -{Ph 2 P(Tol)-CdCdC(Ph)H}] (syn-3a) for R ) Ph, or along with the η 2 -allene complex Cp′(CO) 2 Mn[η 2 -{H(Tol)-CdCdC(Ph)PCy 2 }] (4b, 26% yield, 1:2 mixture of syn/anti isomers) for R ) Cy. On the other hand, subsequent treatment with NH 4 Cl aq affords only η 2 -allene complexes, obtained either as a ca. 1:9 mixture of syn-3a and Cp′(CO) 2 Mn[η 2 -{H(Tol)CdCdC(Ph)PPh 2 }] (4a) (75% yield) for R ) Ph or as a 1:2 mixture of syn-and anti-4b for R ) Cy (74% yield). Combined NMR and single-crystal X-ray diffraction studies (for 2a, anti-4b, and syn-4b) revealed that both type 2 and type 4 species result from a nucleophilic attack of the diorganophosphide onto the remote alkynyl carbon atom in 1 (C γ ), whereas type 3 species results from a nucleophilic attack of the carbene carbon atom (C R ). Complexes 3a and 4a,b are prone to undergo a thermal rearrangement to give the η 1 -phosphinoallene complexes Cp′(CO) 2 Mn[η 1 -{Ph 2 P(Tol)CdCdC(Ph)H}] (5a) and Cp′(CO) 2 Mn[η 1 -{R 2 P(Ph)CdCdC(Tol)H}] (6; 6a: R ) Ph, 6b: R ) Cy), respectively. Reaction of 1 with p-toluenethiol in the presence of NEt 3 (20%) affords a 1.8:1 mixture of Cp′(CO) 2 Mn[η 2 -{TolS(Tol)CdCdC(Ph)H}] (syn-11), resulting from a nucleophilic attack at C R in 1, and Cp′(CO) 2 Mn[η 2 -{H(Tol)CdCdC(Ph)STol}] (12), resulting from a nucleophilic attack at C γ , whereas treatment of 1 with lithium p-toluenethiolate at -80 °C followed by protonation with NH 4 Cl aq gave the same syn-11 and 12 complexes now in a 1:2.3 ratio. Finally, 1 was found to react with cyclohexanone lithium enolate to afford, upon protonation, the η 2 -allene complex Cp′(CO) 2 Mn[η 2 -{H(Tol)CdCdC(Ph)CH(CH 2 ) 4 C(O)}] (syn-13), resulting from a nucleophilic attack at C γ in 1. The solidstate structures of syn-11 and syn-13 are also reported.

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Section: Resultssupporting

confidence: 59%

Section: Discussionmentioning

confidence: 84%

Directed Formation of Allene Complexes upon Reaction of Non-heteroatom-Substituted Manganese Alkynyl Carbene Complexes with Nucleophiles

et al. 2008

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“…Pioneering efforts by Franck-Neumann involved an initial complexation of alkynals 35 (R 1 = H) under UV irradiation to form MMD-allenal intermediate 36 (Scheme 18). Subsequent treatment of 36 with DBU led to MMD-complexed allene 37a as the exo -diastereomer in which the metal auxiliary is “ trans ” to the γ-substituent [32]. The use of Al 2 O 3 as a base in this isomerization completely eroded the exo -selectivity.…”

Section: Manganese Auxiliariesmentioning

confidence: 99%

Carbon-Carbon Bond Formation Facilitated by π-Complexed Organometallic Auxiliaries: An Overview

Roy

Bhat

Lepore

2019

LOC

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A Review: Organometallic moieties attached to substrates via π-complexation play an important role as auxiliaries. As described in the present review, η-linked auxiliaries have been employed to overcome numerous synthesis obstacles that continue to present significant challenges for catalyzed reactions. This has been particularly true in carbon-carbon bond forming reactions involving highly unsaturated systems such as arenes, dienes and allenes, which are emphasized here.

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“…Recently we reported the development of an efficient method for the conversion of a variety of conjugated alkynyl esters to α-substituted conjugated allenyl esters through the use of strong amide bases . We have also investigated the mechanism of a complementary approach pioneered by Franck−Neumann involving the isomerization of manganese alkynyl carbonyls to the corresponding allenes . Allenyl 1,3-dicarboxylates are known to react as both dienophiles , and Michael acceptors .…”

mentioning

confidence: 99%

Michael−Stork Addition of Cyclopentyl Enamine to Allenyl Ketones and Esters

2005

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[Chemical reaction: see text] We report the first examples of a Michael-Stork enamine addition to allenyl esters and ketones. Studies reveal that 2 equivalents of enamine are required for optimal yields. In the case of an allenyl methyl ketone, cyclopentyl enamine addition led to 8-oxobicyclo[3.2.1]octane formation, providing evidence for the in situ formation of an enamine intermediate following the initial Michael-Stork reaction.

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Stabilization of Highly Electrophilic Allenes by Coordination with Manganese. Synthesis of 1-Functionalized Dicarbonyl (η-Methylcyclopentadienyl) (1-2η-3-Formylallene) Manganese Complexes.

Cited by 13 publications

References 0 publications

Directed Formation of Allene Complexes upon Reaction of Non-heteroatom-Substituted Manganese Alkynyl Carbene Complexes with Nucleophiles

Directed Formation of Allene Complexes upon Reaction of Non-heteroatom-Substituted Manganese Alkynyl Carbene Complexes with Nucleophiles

Carbon-Carbon Bond Formation Facilitated by π-Complexed Organometallic Auxiliaries: An Overview

Michael−Stork Addition of Cyclopentyl Enamine to Allenyl Ketones and Esters

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