Copper-Catalyzed Oxy-Alkenylation of Homoallylic Alcohols to Generate Functional<i>syn</i>-1,3-Diol Derivatives
作者:Dean Holt、Matthew J. Gaunt
DOI:10.1002/anie.201501995
日期:2015.6.26
functionalized 1,3‐diol derivatives is reported. Employing a copper‐catalyzed oxy‐alkenylation strategy, a range of readily available, substituted homoallylic alcohol derivatives and alkenyl(aryl) iodonium salts combine to form syn‐1,3‐carbonates in excellent yield and with high selectivity. Furthermore, the products formed are amenable to an iterative reaction sequence, thus affording highly complex polyketide‐like
Studies on the Synthesis of Bafilomycin A<sub>1</sub>: Stereochemical Aspects of the Fragment Assembly Aldol Reaction for Construction of the C(13)−C(25) Segment
作者:William R. Roush、Thomas D. Bannister、Michael D. Wendt、Jill A. Jablonowski、Karl A. Scheidt
DOI:10.1021/jo016413f
日期:2002.6.1
lithium enolate aldolreaction. In contrast, the aldolreaction of 6a and the chlorotitanium enolates of 7a,c were much less sensitive to the nature of the C(15)-hydroxyl protectinggroup. Studies of the reactions of chiral aldehydes with Takai's (gamma-methoxyallyl)chromium reagent 40 are also described. The stereoselectivity of these reactions is also highly dependent on the protectinggroups and stereochemistry
Stereochimie de quelques reactions entre aldehydes et reactifs de Grignard satures et allyliques
作者:H. Felkin、Y. Gault、G. Roussi
DOI:10.1016/s0040-4020(01)92953-9
日期:1970.1
γ-dimethylallyl magnesium bromides) and secondary alkyl [s-butyl magnesium bromide and (1,2-dimethylpropyl) magnesium chloride] Grignardreagents to form pairs of diastereoisomeric alcohols R′—CHMeCHOH—R (R′ = CH2CH, CH2CMe, Et and iPr, respectively). The reactions involving the secondary alkylGrignardreagents are not stereoselective; those involving the allylic Grignardreagents show some stereoselectivity
to produce unisolable allylchromium species which add efficiently to aldehydes or ketones with high degree of stereo- and chemoselectivity. Particularly, high threo selectivity is observed in the reaction of aldehydes and 1-bromo-2-butene and is ascribed to a chair-like six-membered transition state. Simple reduction of allylic and benzylic halides produces biallyls and bibenzyls, while gem-dibromocyclopropanes
n-C5H11, (CH3)2CH, (CH3)3C, C6H5, CH2CH, CH2C(CH3), (E)-CH3CHCH, (E)-C3H7CHCH, (E)-C6H5CHCH) have been carried out in the presence of Lewis acids such as Bu2SnCl2, BF3·Et2O and TiCl4. The stereochemicalcourse of the reactions to give homoallylic alcohols does not necessarily depend on the formation of intermediate Lewis acid-aldehyde complexes, but rather upon the formation of allylmetal compounds