Intramolecular coupling between tricarbonyl(diene)iron complexes and pendant alkenes

Pearson, Anthony J.; Zettler, Mark W.

doi:10.1021/ja00193a023

Cited by 66 publications

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“…This approach is based on a coupling reaction between a diene/Fe(CO) 3 complex and a pendent olefin that was developed in our laboratory several years ago, the outcome of which is equivalent to a [6þ2] ene reaction (non-concerted). 12,13 A simple example of this transformation is shown in Eq. 1.…”

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A synthetic pathway to diquinane and angular triquinane systems via an iron carbonyl promoted tandem [6+2] ene type reaction

2010

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Section: Introductionmentioning

confidence: 99%

A synthetic pathway to diquinane and angular triquinane systems via an iron carbonyl promoted tandem [6+2] ene type reaction

2010

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“…Another possible way to 2-azaspiranes is based on the reaction of tricarbonyl (η 5 -1-alkyl-4-methoxycyclohexadienylium)iron with difunctional nucleophiles [25]. Intramolecular ene-type [6 + 2]-cyclization of Fe(CO) 3 -(cyclohexa-1,3-diene) complexes having a pendant double bond was reported to afford spirocyclic systems [26][27][28]. 2-Azaspiro[4.5]-deca-6,9-diene-3,8-diones were synthesized by tandem Ugi reaction and intramolecular Michael 5-exoaddition [29].…”

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Synthesis of 1-substituted 2-azaspiro[4.5]deca-6,9-dien-8-ones and 2-azaspiro[4.5]deca-1,6,9-trien-8-ones by condensation of 2,6-dimethylphenol with isobutyraldehyde and nitriles

et al. 2012

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1-Substituted 3, 3,7,9-tetramethyl-2-azaspiro[4.5]deca-6,9-dien-8-ones and 3,3,7,9-tetramethyl-2-azaspiro[4.5]deca-1,6,9-trien-8-ones were synthesized by three-component condensation of 2,6-dimethylphenol with isobutyraldehyde and nitriles in concentrated sulfuric acid.Compounds having a 2-azaspiro[4.5]decane skeleton rarely occur in nature. Examples of such structures are annosqualine isolated from the Stems of Annona squamosa [1], spirostaphylotrichins produced by Staphylotrichum coccosporum [2][3][4], triticones (spirocyclic lactams from the fungal plant pathogen Drechslera tritici-repentis [5]), and spiro-arogenate (a spiro-γ-lactam produced by Neurospora crassa from prephenic acid [6,7]). Some 2-azaspiro[4.5]decanes attract certain interest from the viewpoints of medicinal and synthetic organic chemistry. Some synthetic analogs of natural 2-azaspirane derivatives showed high immunosupressive activity [8]. Kazmierski et al. [9] proposed novel HIV-1 protease inhibitors on the basis of a spirocyclic pyrrolidone. It was also found that 2-azaspiranes are formed as intermediate products in the Bischler-Napieralski [10,11] or Ritter [12] syntheses of isoquinolines and phenanthridines. Several synthetic approaches to 2-azaspiro[4.5]-decane derivatives have been reported. Some procedures imply building of 2-azaspiro[4.5]decane skeleton from cyclohexanone or cyclohexene fragments. 2-Azaspiranes can be synthesized according to BuchwaldHartwig via intramolecular cyclization of the corresponding cyclohexanone derivatives [13] and by radical cyclization of N,N-diallyl-2-oxocyclohexanecarboxamides in the presence of Mn(OAc) 3 [14] or of 2-bromo-substituted diene amides, e.g., N-benzyl-2-bromo-N-[1-(cyclohex-1-en-1-yl)vinyl]propanamide, in the presence of CuBr-(C 5 H 5 N) 3 N [15]. A group of methods for the preparation of 2-azaspirane systems is based on dearomatization of arenes with simultaneous construction of pyrrolidinone fragment. Acid-catalyzed intramolecular ipso-cyclization of electron-rich aromatic diazoacetamides [16] or thionium ions generated by reaction of N-benzylglyoxamides with thiols [17] leads to the formation of spirocyclic lactams. 2-Azaspiranes can also be obtained by oxidative radical ipsocyclization of N- [p-methoxy(hydroxy)benzyl]acetamides [18] and substituted N-benzyltrichloroacetamides [19]. developed a procedure for the synthesis of 2-azaspiranes via aromatic nucleophilic substitution in the presence of (η 6 -arene)RuCp + complexes. Another possible way to 2-azaspiranes is based on the reaction of tricarbonyl (η 5 -1-alkyl-4-methoxycyclohexadienylium)iron with difunctional nucleophiles [25]. Intramolecular ene-type [6 + 2]-cyclization of Fe(CO) 3 -(cyclohexa-1,3-diene) complexes having a pendant double bond was reported to afford spirocyclic systems [26][27][28]. 2-Azaspiro[4.5]-deca-6,9-diene-3,8-diones were synthesized by tandem Ugi reaction and intramolecular Michael 5-exoaddition [29].

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“…Suprisingly, when irradiated at 300 nm only the products of a [1,7]-hydrogen shift were obtained, i.e. 58, 59, and 60, respectively (Scheme 7).…”

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“…Attempts to synthesise the trans-lactones fell to a similar fate. While the Sonogashira couplings of triflate 61 with acetylenes 32 and 33 proceeded in good yield to give 62 and 63 respectively, partial hydrogenation did not afford the desired triene, but the products of [1,7]-hydrogen shift, 58 and 59, respectively (Scheme 8).…”

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“…Although [1,7]-hydrogen shifts are known to occur in preference to 6π-electrocyclisation [29] it is also known that subjection to high temperatures drives cyclisation, [30] however, subjecting 58 to increased temperatures failed to afford any cyclised material. To add further understanding to these results, a computational study was undertaken in which heats of formation of starting materials, the products of the electrocyclisation and the [1,5]-hydrogen shifts, and the transition states for these transformations were examined.…”

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Investigating Direct Access to 2‐Oxospiro[4.5]decanones via 6π‐Electrocyclisation

et al. 2007

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The 2-oxospiro[4.5]decan-1-one (or spiro-γ-lactone) structural motif is contained within a number of natural products, for example, the clerodane family of diterpenes. Methods to construct this structural motif are somewhat limited and usually involve multiple functional group interconversions. A novel synthetic approach to this system utilising 6π-electro-The 2-oxospiro[4.5]decan-1-one (1) structural motif exists within a number of natural product groups [e.g. canangone (2), [1] teusalvin A (3) [2] ], of which the clerodanes [3] (i.e. 3) are a major contributor (Figure 1). Considering the usual mode of 2-oxospiro[4.5]decan-1-one construction is to assemble the lactone portion at a later stage, [4][5][6][7][8][9][10][11][12][13][14] which often involves multiple steps, we contemplated the approach of initial γ-lactone inclusion (i.e. construction of the six-membered ring at the later stage). Although this approach presents limitations it does open additional avenues for constructing the 2-oxospiro[4.5]-decan-1-one structural motif (1) directly. In this regard we are only aware of two examples that fit this criterion. [15][16] Of note is the Diels-Alder approach reported by Jung et [a] al. [15] in which allenic lactones 5 and 7 were treated with diene 6 affording the 2-oxospiro[4.5]decan-1-ones 4 and 8 (Scheme 1). Scheme 1. Diels-Alder approach to the 2-oxospiro[4.5]decan-1-one structural motif.With these examples in mind, it seemed reasonable that a 6π-electrocyclisation approach to the six-membered ring (i.e. 2-oxospiro[4.5]decan-1-ones of type 4 and 8) was worthy of investigation. For example, the lactone trienes 9 and 10, via thermal or photochemical conditions, could be transformed into cyclised adducts 11 (12) and 13 (14), which then have the potential to undergo [1,5]-hydrogen shifts, affording the dienes 15 (16) and 17 (18). An additional advantage to this approach would be the relative stereocontrol of the products as described by the Woodward-Hoffmann principles [17][18][19] (Scheme 2). To test the viability of this method a suite of compounds of type 9 were synthesised in good to excellent yields by Sonogashira coupling [20][21][22] of the corresponding alkyne, followed by partial hydrogenation to give the cis-alkenes 28-31, 38-40 (Scheme 3), as well as 45 and 46 (Scheme 4).The partial hydrogenation of these systems was at times capricious, however, neither diimide or boron mediated reduction gave satisfactory results. Furthermore, all attempts to reduce 27 to 31 failed. Though direct synthesis of the aromatic dienes and trienes through Stille coupling is an appealing route, it was found that the triflate 23 did not react with vinyl stannanes at temperatures low enough to

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Intramolecular coupling between tricarbonyl(diene)iron complexes and pendant alkenes

Cited by 66 publications

References 0 publications

A synthetic pathway to diquinane and angular triquinane systems via an iron carbonyl promoted tandem [6+2] ene type reaction

A synthetic pathway to diquinane and angular triquinane systems via an iron carbonyl promoted tandem [6+2] ene type reaction

Synthesis of 1-substituted 2-azaspiro[4.5]deca-6,9-dien-8-ones and 2-azaspiro[4.5]deca-1,6,9-trien-8-ones by condensation of 2,6-dimethylphenol with isobutyraldehyde and nitriles

Investigating Direct Access to 2‐Oxospiro[4.5]decanones via 6π‐Electrocyclisation

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