55058-23-6Relevant academic research and scientific papers
Formal synthesis of borrelidin: A highly enantio- and diastereoselective access to the Morken's C2-C12 intermediate
Gembus, Vincent,Karmazin, Lydia,Uguen, Daniel,Zoller, Thomas
supporting information, p. 359 - 380 (2019/02/25)
In contrast to methyl and isobutyl phenyl sulfone, condensing under basic conditions higher alkyl sulfones and trans-2,3-epoxy-butanol 13c (or its O-benzyl and O-silyl derivatives) proved unfeasible, a difficulty that was overcome by using mono ethers of trans-2,3-epoxy-butane-1,4-diol 35c as the electrophilic reagents. Thus, adding excess BuLi to a mixture of the benzyl ether 35b and sulfone ent-12a, a stereodiad sulfone prepared in pure state from the R-Roche ester, via the O-trityloxy-sulfone ent-12c (X-ray), gave, after elimination by column chromatography of the side-formed regioisomer, a diolsulfone that was next converted to sulfone 20 by means of conventional functional-group modifications. Reacting like-wise this sulfone with the parent O-PMB derivative 35a, and then proceeding to the same purification process and function adjustment, delivered the title fragment in virtually pure state.
Asymmetric epoxidation of α,β-unsaturated aldehydes catalyzed by a spiro-pyrrolidine-derived organocatalyst
Xu, Ming-Hui,Tu, Yong-Qiang,Tian, Jin-Miao,Zhang, Fu-Min,Wang, Shao-Hua,Zhang, Shi-Heng,Zhang, Xiao-Ming
supporting information, p. 294 - 300 (2017/03/01)
The asymmetric epoxidation of α,β-unsaturated aldehydes, catalyzed by a spiro-pyrrolidine (SPD)-derived organocatalyst, has been accomplished with good diastereoselectivities (up to dr >20:1) and with high to excellent enantioselectivities (up to 99% ee).
A computational study of vicinal fluorination in 2,3- Difluorobutane: Implications for conformational control in alkane chains
Fox, Stephen J.,Gourdain, Stephanie,Coulthurst, Anton,Fox, Clare,Kuprov, Ilya,Essex, Jonathan W.,Skylaris, Chris-Kriton,Linclau, Bruno
supporting information, p. 1682 - 1691 (2015/01/30)
A comprehensive conformational analysis of both 2,3-difluorobutane diastereomers is presented based on density functional theory calculations in vacuum and in solution, as well as NMR experiments in solution. While for 1,2-difluoroethane the fluorine gauc
Epoxidation of allylic alcohols on self-assembled polyoxometalates hosted in layered double hydroxides with aqueous H2O2 as oxidant
Liu, Peng,Wang, Changhao,Li, Can
scheme or table, p. 159 - 168 (2009/06/17)
A series of self-assembled polyoxometalate (POM) catalysts were directly immobilized into layered double hydroxides (LDH) by a selective ion-exchange method. Sandwich-type POM species are found to be more favorable than Keggin-type POM for the direct immobilization in LDH, because strict pH controlling is not needed and the LDH hosts can be kept intact. The resulting LDH-POM catalysts were evaluated in the epoxidation of allylic alcohols with aqueous H2O2 as the oxidant without using organic solvent. The heterogeneous LDH-POM catalysts show much higher epoxide selectivity than the corresponding homogeneous Na-POM catalysts, which can be attributed to the beneficial effect of basic LDH host on the suppression of the acid-catalyzed epoxide hydrolysis. The cooperation between the POM guest and the LDH host can achieve up to 99% selectivity of epoxide, 95% H2O2 efficiency and 37200 h-1 TOF without the need of base additives and pH controlling, and the host-guest catalysts can be readily recycled with no apparent loss of catalytic performance.
Effect of structure of the redox molecular sieve TS-1 on the oxidation of phenol, crotyl alcohol and norbornylene
Kerton, Owain J.,McMorn, Paul,Bethell, Donald,King, Frank,Hancock, Frederick,Burrows, Andrew,Kiely, Christopher J.,Ellwood, Simon,Hutchings, Graham
, p. 2671 - 2678 (2008/02/02)
A range of crystalline TS-1 samples with different morphologies as well as the corresponding TS-1 precursor structures have been synthesised using hydrothermal crystallisation. The materials have been characterised using powder X-ray diffraction, IR and Raman spectroscopy and electron microscopy. The materials were used as catalysts for the oxidation of crotyl alcohol, phenol and norbornylene and, in particular, the reactivity of the precursor structures was contrasted with crystalline TS-1. The oxidation of crotyl alcohol, selected as a relatively non-reactive substituted alkene, did not require the TS-1 structure for reactivity and TS-1 precursor structures are active, although crystalline TS-1 was found to be more reactive than the precursor structures. In contrast, phenol hydroxylation is only catalysed by crystalline TS-1. The reaction of phenol is observed to occur only on the exterior surface of large TS-1 crystallites. With smaller crystallites of TS-1, i.e. the size range of interest for catalysis, the rapid subsequent reaction of hydroquinone makes it difficult to determine whether reaction occurs solely on the exterior of the crystallites or at sites within the porous structure. Hence it is suggested that this reaction has limited scope as a probe reaction for the reactivity of sites within the crystallites. It is, however, feasible that phenol hydroxylation is a viable probe reaction for TS-1 type structural units. Norbornylene was studied as an example of a reactant too large to enter the internal pore structure of TS-1 and hence only reaction at pore mouths and external surface sites was possible. Larger TS-1 crystallites were more active for this substrate than suggested by surface area considerations. The results are discussed in terms of the selection of model reactions for the study of TS-1 catalysts. The Owner Societies 2005.
Formation of dihydroxyselenides from allylic alcohols and their conversion to β-hydroxy epoxides via substitution of a phenylselenonyl group
Cooper, Matthew A.,Ward, A. David
, p. 7963 - 7972 (2007/10/03)
Hydroxyselenation of allylic alcohols occurs with high regio- and stereoselectivity to give β,β′-dihydroxyphenylselanyl adducts in high yields. An exception is the reaction of the terminal alcohol, 2-methylprop-2-en-1-ol, which forms only a 1,2-diol product. Generally, the addition is Markovnikov in orientation, but the fact that one anti-Markovnikov addition is observed and that addition to 1,2-disubstituted alkenes shows a strong preference for one regioisomer suggests that an interaction of the allylic alcohol with the selenium atom of the reaction intermediate (which weakens the Cβ-Se bond in the intermediate) is also an important factor in determining the preference for addition of the phenylselanyl group to the double bond carbon nearest the allylic alcohol. The hydroxyselenated adducts of allylic alcohols can be readily converted to β-hydroxy epoxides in good yields via oxidation with m-chloroperbenzoic acid to a selenone and subsequent treatment with base. Hydroxyselenation of crotyl acetate and 3-acetoxycyclohexene is more regiocatholic than hydroxyselenation of the corresponding allylic alcohols. It appears that the known selectivity of additions of phenylselanyl chloride to these acetates in organic solvents is lost when water or a Lewis acid complexes to the acetate group.
Selective epoxidation in dense phase carbon dioxide
Pesiri, David R.,Morita, David K.,Glaze, William,Tumas, William
, p. 1015 - 1016 (2007/10/03)
Selective epoxidations with transition metal catalysts (V, Ti, Mo) and ButOOH proceed with high conversions and high selectivity in dense phase carbon dioxide.
1,5-Asymmetric induction of chirality: Highly diastereoselective addition reactions of organoaluminium reagents into ketone groups in the side-chain of π-allyltricarbonyliron lactone complexes
Ley, Steven V.,Cox, Liam R.,Meek, Graham,Metten, Karl-Heinz,Pique, Carmen,Worrall, Julia M.
, p. 3299 - 3313 (2007/10/03)
The utility of π-allyltricarbonyliron lactone complexes has been extended to include their use as chiral auxiliaries. Organoaluminium reagents add into ketone groups positioned in the side-chain of the allyl ligand to afford the corresponding tertiary alcohol complexes in good to excellent yield and with excellent diastereocontrol. Enantiomerically enriched complexes can be synthesised using the Sharpless asymmetric epoxidation protocol as the source of chirality. Addition products derived from endo ketones can be converted into the corresponding (E,E)-η4-dienetricarbonyliron complexes upon treatment with barium hydroxide solution without loss of diastereo- or enantio-purity.
Halocyclization of Unsaturated Alcohols and Carboxylic Acids Using Bis(sym-collidine)iodine(I) Perchlorate
Evans, Robert D.,Magee, Joseph W.,Schauble, J. Herman
, p. 862 - 868 (2007/10/02)
Reaction of I(collidine)2(1+) ClO4(1-) with unsaturated alcohols and carboxylic acids in dichloromethane at ambient temperature has afforded three- to seven-membered-ring iodoethers and four- to seven-membered-ring iodolactones, respectively, in moderate
Enantioselective Diastereospecific Synthesis of anti-α-Alkyl-β-hydroxy Esters through Cuprate Opening of Glycidic Esters
Mulzer, Johann,Lammer, Ortrud
, p. 2178 - 2190 (2007/10/02)
A diastereospecific chain elongation of the aldehydes 1 to anti-αalkyl-β-hydroxy esters 2 via the intermediates 4 - 7 is described.By means of the Sharpless epoxidation, 2 may be obtained with >90percent ee in either enantiomer.
