Flucht vor der Tyrannei des Zinns: auf der Suche nach metallfreien Radikalquellen

Baguley, Paul A.; Walton, John C.

doi:10.1002/(sici)1521-3757(19981116)110:22<3272::aid-ange3272>3.3.co;2-d

Cited by 12 publications

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“…However, the reported methods did not work well with primary alkyl iodides and xanthates owing to inefficient iodineatom transfer and xanthate-group transfer, respectively. Recently, we also reported a tin-free acylation approach RX SO 2 Et R AIBN + (1) X= I, xanthate…”

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confidence: 99%

Tin-Free Radical-Mediated C��C-Bond Formations with Alkyl Allyl Sulfones as Radical Precursors

Kim

Lim

2002

Angew. Chem. Int. Ed.

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confidence: 99%

Tin-Free Radical-Mediated C��C-Bond Formations with Alkyl Allyl Sulfones as Radical Precursors

Kim

Lim

2002

Angew. Chem. Int. Ed.

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“…[12] For a tin-free approach, [13] we implemented the findings of our previous studies on the radical rearrangement of silyloxy radicals into the corresponding silyl radicals. [12] For a tin-free approach, [13] we implemented the findings of our previous studies on the radical rearrangement of silyloxy radicals into the corresponding silyl radicals.…”

Section: Methodsmentioning

confidence: 99%

Radical Alkylation of Bis(silyloxy)enamine Derivatives of Organic Nitro Compounds

2006

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“…To circumvent the use of toxic tin compounds, many research groups are currently looking at environmentally benign radical processes. [2] Electron-transfer reagents have successfully been used in this context. In particular, samarium diiodide (SmI 2 ) has been found to be a highly efficient electron-transfer reagent for conducting various radical processes.…”

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confidence: 99%

A New Method for the Generation of Titanium(III) Complexes and its Application in Pinacol Coupling Reactions

Knoop

Studer

2005

Adv Synth Catal

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A new method for the in situ generation of various Ti(III) complexes is presented. Cyclohexadienyl-Ti(IV) derivatives, which are readily prepared from the corresponding lithiated cyclohexadienes, afford the corresponding Ti(III) complexes upon thermal C À Ti-bond homolysis. The Ti(III) compounds generated using this novel method have successfully been used in the reductive dimerization of benzaldehyde. In particular, TiBr 3 , TiCp 2 Cl and Ti(O-i-Pr) 3 have been generated via this approach. Moreover, the method also offers an entry to new chiral Ti(III) complexes as documented by the preparation of Ti(III)CpTADDOLate.Keywords: radical chemistry; reductive cyclization; stereoselective reductions; synthetic methods; titanium Radical chemistry has gained increasing importance during the last 30 years.[1] In contrast to ionic chemistry, many functional groups are tolerated under radical conditions. Several methods for the clean generation of radicals have been reported to date. However, most of the radical reactions are conducted using toxic trialkyltin hydrides. To circumvent the use of toxic tin compounds, many research groups are currently looking at environmentally benign radical processes.[2] Electron-transfer reagents have successfully been used in this context. In particular, samarium diiodide (SmI 2 ) has been found to be a highly efficient electron-transfer reagent for conducting various radical processes.[3] However, SmI 2 is rather expensive and is readily oxidized on air.As an alternative to SmI 2 , Ti(III) complexes have been studied by various groups. [4 -11] Nugent and RajanBabu showed that titanocene(III) chloride can be applied to reductively open epoxides.[5] The b-titanoxy radicals thus generated can be used in radical cyclizations and intermolecular addition reactions. Gansäuer [6,7] later showed that the epoxide openings can be performed using catalytic [8] amounts of titanocene(III) chloride.Reduction of activated alkyl halides have been achieved using Ti(III).[9] Moreover, Ti(III) complexes have successfully been used in pinacol reactions. [10,11] Even enantioselective couplings have recently been reported. [12] Most of the Ti(III) complexes studied have been generated from the corresponding Ti(IV) compounds and a coreducing reagent. [13] Recently, we published our results on the use of cyclohexadienyl-Ti compounds in ionic allylations (Scheme 1). [14] We assumed that these compounds may also offer a clean entry to Ti(III) complexes upon simple thermal Ti-carbon bond homolysis. In contrast to established methods for the generation of Ti(III) derivatives, a coreducing reagent is not necessary in our approach. [15] Since the starting cyclohexadienyl-Ti(IV) compounds are readily prepared by transmetalation using the appropriate Ti(IV) complex, new unexplored Ti(III) reagents should be available via this route. In this communication we report first results on the use of cyclohexadienyl-Ti(IV) derivatives as precursors for Ti(III) complexes. Moreover, these reducing reagents will be appli...

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Flucht vor der Tyrannei des Zinns: auf der Suche nach metallfreien Radikalquellen

Cited by 12 publications

References 0 publications

Tin-Free Radical-Mediated C��C-Bond Formations with Alkyl Allyl Sulfones as Radical Precursors

Tin-Free Radical-Mediated C��C-Bond Formations with Alkyl Allyl Sulfones as Radical Precursors

Radical Alkylation of Bis(silyloxy)enamine Derivatives of Organic Nitro Compounds

A New Method for the Generation of Titanium(III) Complexes and its Application in Pinacol Coupling Reactions

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Flucht vor der Tyrannei des Zinns: auf der Suche nach metallfreien Radikalquellen

Cited by 12 publications

References 0 publications

Tin-Free Radical-Mediated C���C-Bond Formations with Alkyl Allyl Sulfones as Radical Precursors

Tin-Free Radical-Mediated C���C-Bond Formations with Alkyl Allyl Sulfones as Radical Precursors

Radical Alkylation of Bis(silyloxy)enamine Derivatives of Organic Nitro Compounds

A New Method for the Generation of Titanium(III) Complexes and its Application in Pinacol Coupling Reactions

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Tin-Free Radical-Mediated C��C-Bond Formations with Alkyl Allyl Sulfones as Radical Precursors

Tin-Free Radical-Mediated C��C-Bond Formations with Alkyl Allyl Sulfones as Radical Precursors