Chiral organometallic reagents. Part XXV.1 The stereochemistry of the ring opening of cyclopropylallyllithium compounds

Hoffmann, Reinhard W.; Koberstein, Ralf

doi:10.1039/a908668d

Cited by 19 publications

(11 citation statements)

References 30 publications

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“…3-Ethyloct-7-en-3-ol (10a). Colorless oil; t R 8.57; R f 0.32 (hexane/EtOAc 10:1); n (film) 3365 (OH), 3068 cm À1 (C]CH); d H 0.86 (6H, t, J¼7.5, 2ÂCH 3 ), 1.17 (1H, s, OH), 1.40-1.50 (8H, m, 2ÂCH 2 CH 3 and CH 2 CH 2 CHOH), 2.06 (2H, CH 2 CH]CH 2 ), 5.00 (2H, m, CH 2 CH]CH 2 ), 5.81 (1H, ddt, J¼17.2, 10.3, 6.5, CH 2 CH]CH 2 ); d C 7.7 (2ÂCH 3 ), 22.7 (2ÂCH 2 CH 3 ), 31.0 (CH 2 CH 2 COH), 34.2 (CH 2 CH]CH 2 ), 37.6 (CH 2 COH), 74.5 (COH), 114.5 (CH 2 ]CH), 138.7 (CH 2 ]CH); m/z 156 (M þ , 0,03%), 127 (28), 87 (96), 86 (11), 69 (15), 57 (19); HRMS [M þ þH] calcd for C 10 H 21 O 157.158610 H 21 O 157. , found 157.1580. Yellow oil; t R 10.53; R f 0.30 (hexane/EtOAc 10:1); n (film) 3468 cm À1 (OH); d H 0.91 (6H, t, J¼5.4, 2ÂCH 3 ), 1.27-1.37, 1.42 (4H and 8H, 2m, 2ÂCH 2 CH 2 CH 3 and 2ÂCH 2 CH 2 COH), 2.05 (2H, m, CH 2 CH]CH 2 ), 4.98 (2H, m, CH]CH 2 ), 5.83 (1H, ddt, J¼12.6, 7.8, 5.1, CH]CH 2 ); d C 14.7 (2ÂCH 3 ), 16.7…”

Section: 4mentioning

confidence: 99%

Cyclopropylmethyl- and cyclobutylmethyllithium by an arene-catalyzed lithiation. Stability and reactivity

2010

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Section: 4mentioning

confidence: 99%

Cyclopropylmethyl- and cyclobutylmethyllithium by an arene-catalyzed lithiation. Stability and reactivity

2010

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“…In contrast, the back face of carbanion 94 a is hindered as a result of the anti orientation of the thiophenyl group relative to the C−Li bond which is necessary for maximizing n‐σ* overlap. Enantioenriched α ‐lithio sulfides have also been generated by a retrocarbolithiation of a cyclopropyl group 106. The lithiated intermediate 99 can be trapped with methyl iodide or stannylating agents to provide products 100 with retention of configuration (Scheme , Dur=2,3,5,6‐tetramethylphenyl).…”

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.

232

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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.

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“…The filtrate was concentrated and the residue was purified by flash chromatography (pentane/ethyl acetate, 10:1). 1 7, 69.2, 127.2, 127.6, 128.9, 129.2, 129.4, 135.8, 138.1, 138.3; elemental analysis (%) calcd for C 14 H 12 BrOS (342.0): C 48.93, H 3.52; found: C 48.88, H 3.52. The absolute and relative configuration was secured by X-ray crystal structure analysis, see below.…”

Section: Major Diastereomer (à)-(Rr)-15mentioning

confidence: 99%

Highly Enantiomerically Enrichedα-Haloalkyl Grignard Reagents

et al. 2000

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alpha-Chloro- and alpha-bromoalkyl Grignard reagents 11 and 30 with > 97% ee (enantiomeric excess) were generated by a sulfoxide/magnesium exchange reaction from the enantiomerically and diastereomerically pure sulfoxides 25 and 27. The resulting alpha-haloalkyl Grignard reagents are configurationally stable at -78 degrees C. Racemization sets in at or above -60 degrees C, especially when the solution contains bromide ions. In the absence of halide ions, the configurational stability extends up to -20 degrees C, when chemical decomposition commences.

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Chiral organometallic reagents. Part XXV.1 The stereochemistry of the ring opening of cyclopropylallyllithium compounds

Cited by 19 publications

References 30 publications

Cyclopropylmethyl- and cyclobutylmethyllithium by an arene-catalyzed lithiation. Stability and reactivity

Cyclopropylmethyl- and cyclobutylmethyllithium by an arene-catalyzed lithiation. Stability and reactivity

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

Highly Enantiomerically Enrichedα-Haloalkyl Grignard Reagents

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