- Stereoselective Protonation of Carbanions, 1. - Diastereoselective Protonation of C-H-Activated Cyclohexane Derivatives
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The diastereoselectivity of the kinetically controlled protonation of carbanions derived from 4-tert-butyl-1-X-cyclohexanes (1: X = CN, 2: X = CO2Me, 2-Si: X = C(OMe)OSiMe3, 3: X = COPh, 4: X = SO2Ph) is systematically investigated.By variation of (a) the
- Gerlach, Uwe,Haubenreich, Thomas,Huenig, Siegfried,Keita, Yango
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p. 1205 - 1216
(2007/10/02)
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- DIASTEREOSELECTIVE PROTONIERUNG VON CARBANIONEN
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Despite of very small side differentiation in 3-Li the ratio of cis-3: trans-3 can be shifted from 41: 59 to 85: 15 by variation of the proton sources.
- Gerlach, Uve,Huenig, Siegfried
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p. 5805 - 5808
(2007/10/02)
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- Cob(I)alamin Differentiating Alkenes During Saturation
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The olefins 2, 7, 11, and 19 have been reduced using catalytic amounts of cob(I)alamin(1(I)).During a slow saturation, the catalyst is able to differentiate the two diastereotopic faces of the endocyclic double bonds in 11 (t1/2 40 d) and 19 (t1/2 80 d, cf.Scheme 4).The substrates 2 (t1/2 1 h, cf.Scheme 2) and 7 (t1/2 4 h, cf.Scheme 3) are reduced much faster.A rationalization of the data can be obtained formulating tertiary alkylcobalamins as intermediates.Of the oxime 6 ( cf.Scheme 2) and the p-bromobenzoate 23 (cf.Scheme 5) the structures have been determined by X-ray analysis.
- Schoenholzer, Peter,Suess, Daniel,Wan, Terence S.,Fischli, Albert
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p. 669 - 683
(2007/10/02)
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