112489-57-3Relevant articles and documents
Regio- And stereoselective synthesis of alkyl allylic ethers via gold(l)-catalyzed intermodular hydroalkoxylation of allenes with alcohols
Zhang, Zhibin,Widenhoefer, Ross A.
supporting information; scheme or table, p. 2079 - 2081 (2009/04/10)
Reaction of 1-phenyl-1,2-butadiene with 2-phenyl-1-ethanol catalyzed by a 1:1 mixture of a gold(l) W-heterocyclic carbene complex and AgOTf at room temperature for 1 h led to isolation of (E)-(3-phenethoxy-1-butenyl)benzene in 96% yield as a single regio-
"Chirality transfer" in iron-mediated dienylic substitutions via highly enantiomerically enriched planar chiral 1-phenylsulfonyl-substituted tricarbonyl(η5-pentadienyl)iron(1 +) complexes
Enders, Dieter,Jandeleit, Bernd,Von Berg, Stefan
, p. 219 - 236 (2007/10/03)
The preparation of highly diastereo-and enantiomerically enriched planar chiral 1-phenylsulfonyl-substituted tricarbonyl(η5-pentadienyl)iron(1 +) complexes 7 [syn,syn-(1R,5R)-7 and syn,syn-(1S,5S)-7 (cisoid-or U-forms); de > 99% ≡ 5-syn-CH3/5-anti-CH3 ? 100:1, ee > 99%; 87% quant. from resolved 6] is described. Starting from the enantiopure diene (1E,3E,S)-5 both enantiomers of the cationic complexes syn,syn-7 become readily accessible via chromatographic resolution of the diastereomeric mixture of the corresponding neutral tricarbonyl(η4-diene)iron(0) complexes 6 [(1R,5S)-6 ≡ ψ-endo-6 and (1S,5S)-6 ≡ ψ-exo-6; de > 99%, ee > 99%; 85% quant. prior to resolution]. The nucleophilic addition of hetero and carbon atom nucleophiles (morpholine, silyl enol ether 8 and silyl ketene acetal 9) to the racemic complex syn,syn-(1R/S,5R/S)-7 afforded the neutral ε-substituted tricarbonyl(η4-diene)iron(0) complexes rac-ψ-exo-10a-c in moderate yields [43-68% from syn,syn-(1R/S,5R/S)-7] as single geometrical isomers [(E,Z) or (E,E); kinetic (U-form/strong nucleophile) or thermodynamic (S-form/less reactive nucleophile) control]. Likewise, nucleophilic addition to the stereochemically homogeneous complexes syn,syn-(1R,5R)-7 or syn,syn-(1S,5S)-7 followed by oxidative cleavage of the carbonyliron fragment offers an access to ε-substituted dienes 11a-c in moderate to fair yields [45-65%, (E,Z)/(E,E) = > 85:1-1:3] with enantiomeric excesses ranging from > 99%/98.9% [(1E,3Z,R)-11a/(1E,3Z,S)-11a] to 93% [(6E,8E,S)-11b]. The stereochemistry of the formation and the stereochemical pathways of the nucleophilic addition reactions of the nonracemic complexes syn,syn-7 leading to the dienes 11a-c as well as spectroscopic and structural details are discussed. Furthermore, the reaction proceeds with virtually complete "chirality transfer" from C-O via C-Fe to C-N or C-C, respectively, with either retention or inversion of stereochemistry of the stereogenic centre with respect to the starting material (S)-1 depending strongly on the reaction conditions. The observed ε-regioselectivity of the nucleophilic addition reaction displays the synthetic equivalence of the cationic complexes of type syn,syn-7 with a planar chiral a6-synthon allowing an umpolung of the classical d6-chemistry.
1,3-dipolar cycloaddition reactions of azomethine ylides on enantiomerically pure (E)-γ-alkoxy-α,β-unsaturated esters
Annunziata,Cinquini,Cozzi,Raimondi,Pilati
, p. 1329 - 1342 (2007/10/02)
Enantiomerically pure (E)-γ-alkoxy-α,β-unsaturated esters were reacted with azomethine ylides obtained from glycine imines in the presence of LiBr and diazabicyloundecene (DBU), to afford tetrasubstituted pyrrolidines with complete regiocontrol and fair to excellent diastereoselectivity (only two diastereoisomers formed in up to 96: 4 diastereoisomeric ratio). The results are compared with those of other 1,3-dipolar cycloadditions, and the origin of stereocontrol is discussed.
