Useful Enantioselective Bicyclization Reactions Using an N-Protonated Chiral Oxazaborolidine as Catalyst
作者:Gang Zhou、Qi-Ying Hu、E. J. Corey
DOI:10.1021/ol035542a
日期:2003.10.1
[reaction: see text] Nine examples are reported of enantioselective [4 + 2] cycloaddition reactions of achiral, acyclic substrates to form chiral bicyclo[4.3.0]nonane or bicyclo[4.4.0]decane derivatives.
Allylation of Nitrosobenzene with Pinacol Allylboronates. A Regioselective Complement to Peroxide Oxidation
作者:Robert E. Kyne、Michael C. Ryan、Laura T. Kliman、James P. Morken
DOI:10.1021/ol101472k
日期:2010.9.3
Addition of nitrosobenzene to pinacol allylboronates leads to oxidation of the organoboron with concomitant rearrangement of the substrate alkene. This reaction appears to proceed by allylboration of the nitroso group in analogy to carbonyl and imine allylation reactions. Remarkably, the N−O bond is cleaved during the reaction such that simple alcohols are the final reaction product.
Intramolecular Diels–Alder reactions using chiral ruthenium Lewis acids and application in the total synthesis of ent-ledol
作者:Sirinporn Thamapipol、E. Peter Kündig
DOI:10.1039/c1ob06121f
日期:——
ligand BIPHOP-F and a Cp or an indenyl ‘roof’ can efficiently catalyze asymmetric intramolecular Diels–Alder reactions of trienes to form bicyclic adducts with good to excellent asymmetric induction. This reaction forms the key step in a totalsynthesis of ent-ledol in 96% ee. The synthesis also helps to clarify the stereochemical assignment of ledol and inconsistencies in the measured optical rotation
Ni(0)-Catalyzed 1,4-Selective Diboration of Conjugated Dienes
作者:Robert J. Ely、James P. Morken
DOI:10.1021/ol101797f
日期:2010.10.1
stereoselective 1,4-diboration of conjugated dienes with B2(pin)2 was accomplished with Ni(cod)2 and PCy3 as the catalyst. This reaction broadens the substrate scope of current methods for catalytic diene diboration by including internal and sterically hindered dienes, and it proceeds efficiently at low catalyst loadings. The intermediate allylboronate was oxidized to the stereodefined allylic 1,4-diol.
Trimethylsilyl triflate catalysed Diels-Alder reaction of TMS ethers of conjugated dienols with cyclic enones: Evidence for an endo transition state, and first application to synthesis of enantiopure octalins
作者:Richard K. Haynes、Kwok-Ping Lam、Kit-Ying Wu、Ian D. Williams、Lam-Lung Yeung
DOI:10.1016/s0040-4020(98)01020-5
日期:1999.1
adduct acetal, whose controlled hydrolysis gives the hemiacetal with an α-axial methyl group. The adduct is thereby differentiated from the AlCl3 DA adduct, and may be converted into the latter by treatment with p-toluenesulfonic acid in aqueous THF or by AlCl3 in dichloromethane. In similar fashion, TMSOTf provides full acetal adducts from 2-cyclohexenone, 2-cycloheptenone and methyl vinyl ketone. The