Titanocene(<scp>II</scp>)‐Promoted Multicomponent Reactions Utilizing Alkynyl Sulfones, Alkenyl Sulfones, and Carbonyl Compounds: A Novel Method for the Synthesis of Vinylallenes

Ogata, Akitoshi; Nemoto, Masami; Kobayashi, Kenji; Tsubouchi, Akira; Takeda, Takeshi

doi:10.1002/chem.200601326

Cited by 19 publications

(4 citation statements)

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“…114) are generated by metathesis, [61] carbometalation, [62] α-elimination, [63] and cycloaddition. [64] Scheme 28. Cp2Ti[P(OEt)3]2 mediated synthesis of allenes…”

Section: Elimination Of Titaniummentioning

confidence: 99%

Synthesis of Allenes by 1,2-Elimination

Armstrong

2020

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Allenes represent an extremely important class of organic molecules, which, as a result of their twisted orthogonal π-systems can possess axial chirality. A wide array of methods for allene synthesis have been reported, such as the substitution of propargylic electrophiles, isomerization of alkynes and sigmatropic rearrangement. An alternative approach for the synthesis of allenes is 1,2-elimination of an appropriately substituted precursor. This mini-review highlights recent examples of 1,2-elimination processes, which target allenes including both polar and radical processes. The main focus is upon how control over the stereospecificity (e.g. syn- or anti-) of the 1,2-elimination process can enable the synthesis of enantioenriched axially chiral allenes. Recent developments in this field are presented including both enantiospecific and catalytic asymmetric methods.

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“…114) are generated by metathesis, [61] carbometalation, [62] α-elimination, [63] and cycloaddition. [64] Scheme 28. Cp2Ti[P(OEt)3]2 mediated synthesis of allenes…”

Section: Elimination Of Titaniummentioning

confidence: 99%

Synthesis of Allenes by 1,2-Elimination

Armstrong

2020

COC

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“…We also found that various alkynyl phenyl sulfones reacted with ( Z )-alkenyl methyl sulfones ( 2 ) in the presence of 1 to form the alkenylation products, 1-(phenylsulfonyl)-1,3-dienyltitanium compounds. These compounds produced titanium vinylvinylidene complexes upon treatment with another equivalent of 1 . These findings prompted us to investigate the synthetic utility of the titanocecene(II)-promoted alkenylation of unsaturated compounds using alkenyl sulfones.…”

Section: Introductionmentioning

confidence: 99%

Titanocene(II)-Promoted Stereoselective Alkenylation Utilizing (Z)-Alkenyl Sulfones

et al. 2007

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The stereoselective alkenylation of unsaturated compounds by means of a (Z)-alkenyl sulfone-titanocene(II) system is described. Treatment of alkynes and (Z)-alkenyl methyl sulfones with the titanocene(II) reagent Cp2Ti[P(OEt)3]2 produced conjugated dienes. This alkenylation system is also applicable to polar C=O bonds; the simple mixing of carbonyl compounds, (Z)-alkenyl methyl sulfones, and the titanocene(II) reagent formed allylic alcohols. The advantages of alkenylation are that it requires no prepreparation of the alkenylmetal reagent and that it proceeds with complete stereoselectivity.

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“…2 This alkenylation was successfully applied to the stereoselective preparation of titanium vinylvinylidene complexes from alkynyl phenyl sulfones, which involved regioselective coupling of alkynyl and alkenyl sulfones. 3 These results prompted us to further investigate the stereoselective preparation of functionalized dienes 3, 4 and 5 by the titanocene(II)-promoted reactions of functionalized alkynes 6, 7 and 8 with (Z)-alkenyl methyl sulfones 1 (Scheme 1).…”

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confidence: 98%