Chiral Organometallic Reagents, I Stereoselective Exchange of Diastereotopic Bromine Atoms by Lithium in 1,1‐Dibromo‐3‐(trimethylsilyloxy)alkanes

Hoffmann, Reinhard W.; Bewersdorf, Martin; üger, Michael Kr; Mikolaiski, Wolfgang; ürmer, Rainer St

doi:10.1002/cber.19911240543

Cited by 39 publications

(12 citation statements)

References 34 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…α ‐Halo organolithium reagents, which are useful intermediates for the synthesis of epoxides and cyclopropanes, are usually prepared by Li/Sn or Li/halogen exchange 127–131. The epimeric intermediates 119 and epi ‐ 119 were generated by the former route and provided diastereomeric epoxides upon reaction with acetone, thus demonstrating useful configurational stability under the reaction conditions (Scheme ) 132.…”

Section: Chiral Organolithium Reagentsmentioning

confidence: 99%

Configurational Stability and Transfer of Stereochemical Information in the Reactions of Enantioenriched Organolithium Reagents

Basu

Thayumanavan

2002

Angew. Chem. Int. Ed.

233

View full text Add to dashboard Cite

The conversion of a prochiral methylene group into a stereogenic center by means of a lithiation/substitution sequence has emerged as a powerful synthetic transformation over the past 15 years. This reaction proceeds via a chiral organolithium intermediate, and the stereochemical fidelity of the overall reaction sequence is intimately dependent on the stereochemical behavior of the chiral organolithium as well as on the rate and stereochemical sense of the electrophilic substitution step. Chiral organolithium reagents were first reported by Letsinger, Curtin, and Applequist half a century ago. The lithiated intermediates in these early studies were not highly configurationally stable, and applications in stereoselective synthesis were not immediately forthcoming. The two decades that followed the 1980 report by Still and Sreekumar of a configurationally stable α‐oxyorganolithium were marked by an increased interest in these reagents. As the synthetic applications of chiral organolithium reagents have grown, so have accompanying mechanistic studies of these intermediates which serve as the basis for this review.

show abstract

Section: Chiral Organolithium Reagentsmentioning

confidence: 99%

Configurational Stability and Transfer of Stereochemical Information in the Reactions of Enantioenriched Organolithium Reagents

Basu

Thayumanavan

2002

Angew. Chem. Int. Ed.

233

View full text Add to dashboard Cite

show abstract

“…5,5‐Dibromo‐2‐methylpentane‐2,3‐diol (17): To a solution of 2‐methyl‐5,5‐dibromo‐2‐pentene24 (9.00 g, 37.2 mmol, 1.00 equiv.) in acetone (90 mL) were added N ‐methylmorpholine N ‐oxide (50 wt.‐% in H 2 O, 11.6 mL, 55.8 mmol, 1.50 equiv.)…”

Section: Methodsmentioning

confidence: 99%

Reactivity of α‐Bromosulfones Obtained from gem‐Dibromides

et al. 2015

View full text Add to dashboard Cite

α‐Bromosulfones have been synthesized diastereoselectively by reaction of β‐hydroxy gem‐dibromides with aromatic sulfinates. More steric demanding groups in the β‐position led to increased stereoselectivity in these SN2 reactions. Lithiated α‐bromosulfones react diastereoselectively with alkylating agents, aldehydes, and ketones. No configurational stability of the lithiated α‐bromosulfones was observed except fast equilibration towards a chelate‐stabilized intermediate. Treatment of the α‐bromosulfone with methylcuprate resulted in substitution of the bromine by a methyl group.

show abstract

“…TMSOTf, Me 2 S CH 2 Cl 2 , −78 °C to rt + 20% (72) A synthesis of cross-conjugated 2-cyclopenten-1-ones from dialkenyl ketones is readily induced by TMSOTf (eq 73). A strong fluorine-directing effect has been observed for such Nazarov-type cyclization, as mixtures of products have been observed for nonfluorinated dialkenyl ketones.…”

Section: Co-bis-silylationmentioning

confidence: 99%

“…On the other hand, silylation can be carried out with TMS-imidazole albeit in lower yields, while the treatment with trimethylsilyl chloride is unsuccessful 72. BuLi, THF/ether, −110 °C 2.…”

mentioning

confidence: 99%