61828-36-2Relevant academic research and scientific papers
Facile and highly diastereoselective synthesis of syn- and cis-1,2-diol derivatives from protected α-hydroxy ketones
Jahn, Emanuela,Smr?ek, Jakub,Pohl, Radek,Císa?ová, Ivana,Jones, Peter G.,Jahn, Ullrich
, p. 7785 - 7798 (2015/12/31)
An efficient method for the synthesis of monoprotected syn- or cis-1,2-diol derivatives by reduction of easily accessible α-(2,2,6,6-tetramethylpiperidinyloxy) ketones is reported. The α-(tetramethylpiperidinyloxy) group as the stereodirecting group induces in unhindered acyclic or cyclic ketones complete syn- or cis-diastereoselectivity, respectively, with L-Selectride. For more hindered derivatives, where L-Selectride becomes unreactive, LiAlH4 proved effective, essentially showing the same high selectivity. The diastereoselectivity of the reduction can be rationalized for acyclic ketones by the Felkin-Anh model, whereas for cyclic substrates, attack from the face opposite to the tetramethylpiperidinyloxy group predictably prevails with high selectivity regardless of the substitution pattern. The liberation of free diols was achieved by reductive N-O bond cleavage of the alkoxyamine unit. Monoprotected syn- and cis-1,2-diols were synthesized by reduction of ketones bearing the stereodirecting α-(2,2,6,6-tetramethylpiperidinyloxy) group. The latter induces syn- or cis-selectivity in unhindered acyclic or cyclic ketones with L-Selectride, whereas the smaller LiAlH4 induced excellent diastereoselectivity with hindered ketones. Free 1,2-diols were liberated by reductive N-O bond cleavage.
Osmium impregnated on magnetite as a heterogeneous catalyst for the syn-dihydroxylation of alkenes
Cano, Rafael,Pérez, Juana M.,Ramón, Diego J.
, p. 177 - 182 (2014/01/06)
A new catalyst derived from osmium has been prepared, fully characterized and tested in the dihydroxylation of alkenes. The catalyst was prepared by wet impregnation methodology of OsCl3·3H2O on a commercial micro-magnetite surface. The catalyst allowed the reaction with one of the lowest osmium loadings for a heterogeneous catalyst and was selective for the monodihydroxylation of 1,5-dienes. Moreover, the catalyst was easily removed from the reaction medium by the simple use of a magnet. The selectivity of catalyst is very high with conversions up to 99%. Preliminary kinetics studies showed a first-order reaction rate with respect to the catalyst.
Promiscuous substrate binding explains the enzymatic stereoand regiocontrolled synthesis of enantiopure hydroxy ketones and diols
Kurina-Sanz, Marcela,Bisogno, Fabricio R.,Lavandera, Ivan,Orden, Alejandro A.,Gotor, Vicente
experimental part, p. 1842 - 1848 (2011/02/25)
Regio- and stereoselective reductions of several diketones to afford enantiopure hydroxy ketones or diols were accomplished using isolated alcohol dehydrogenases (ADHs). Results could be rationalised taking into account different (promiscuous) substrate-binding modes in the active site of the enzyme. Furthermore, interesting natural cyclic diketones were also reduced with high regio- and stereoselectivity. Some of the 1,2 and 1,3-diketones used in this study were reduced by employing a low excess of the hydrogen donor (2-propanol) due to the quasi-irreversibility of these ADH-catalysed processes. Thus, using lower quantities of co-substrate, scale-up could be easily achieved.
Kinetic resolution of 1,2-diols through highly site- and enantioselective catalytic silylation
Zhao, Yu,Mitra, Aurpon W.,Hoveyda, Amir H.,Snapper, Marc L.
, p. 8471 - 8474 (2008/09/18)
(Chemical Equation Presented) Resolved to silylate: A chiral silylation catalyst is used for kinetic resolution of three classes of acyclic 1,2-diols. The catalyst differentiates, with excellent precision, between the two hydroxy groups of a substrate. The majority of the diols, obtained in high enantiomeric purity, cannot be accessed with similar stereochemical purity through catalytic asymmetric dihydroxylation.
Diols obtained via chemo and regioselective ring opening of epoxy alcohols: A straightforward synthesis of 2S,3S-octandiol
Bonini, Carlo,Righi, Giuliana
, p. 1531 - 1538 (2007/10/02)
Epoxy alcohols are regio and chemoselectively opened to the corresponding iodohydrins and then reduced in situ to diols; the application of the described procedure leads to a short asymmetric of a well known pheromone. Also homoallylic (E and Z) epoxy alcohols and its benzylated derivatives shows high preference for regioselective opening affording the corresponding 1,3 diol.
Stereochemical Evidence for an Alkylated Perepoxide Intermediate
Bloodworth, A. J.,Bowyer, Kevin J.,Mitchell, John C.
, p. 1124 - 1128 (2007/10/02)
Peroxymercuration of (Z)-pent-2-ene afforded single stereoisomers of 2-(bromomercurio)-3-(tert-butylperoxy)pentane (M1) and 3-(bromomercurio)-2-(tert-butylperoxy)pentane (M2), which were separated by medium pressure liquid chromatography.Iodinolysis of each of these gave a pair of epimeric β-iodopentyl tert-butyl peroxides (I1a and I1B from M1, and I2A and I2B from M2), which were similarly separated.When treated with silver trifluoroacetate, the regioisomers I1A and I2A each yielded the same 5:3 mixture of 3-(tert-butylperoxy)-2-(trifluoroacetoxy)pentane (T1) and 2-(tert-butylperoxy)-3-(trifluoroacetoxy)pentane (T2).Independent experiments showed that the starting iodides and the product trifluoroacetates were stereochemically stable under the reaction conditions.Hence, the results are taken to provide compelling evidence for the intermediacy of a tert-butylated perepoxide (PA) that is sufficiently long-lived to be attacked at each ring carbon atom.However, the epimeric regioisomers I1B and I2B each reacted with silver trifluoroacetate to afford a single, new, trifluoroacetate with retention of both regio- and stereochemistry.This is taken to provide evidence for a new mechanism of substitution involving a six-centered cyclic transition state.Product correlations for similar substitutions with analogous bromo peroxides for which stereochemistries are identified by assuming trans addition for peroxymercuration and retention of configuration during bromodemercuration indicate that the alkylated perepoxide (PA) has the structure with cis-alkyl groups.This was confirmed by identifying the stereochemistry of T1 and T2 by LiAlH4 reduction to threo-pentane-2,3-diol.
DIASTEREOSELECTIVITY OF THE MERCURATION OF ACYCLIC ALLYLIC ALCOHOLS
Giese, Bernd,Bartmann, Dieter
, p. 1197 - 1200 (2007/10/02)
The diastereoselectivity of the mercuration of acyclic alkenes 4 can be reversed by changing the substituent in the allylic position; with alcohols the erythro isomers 5 and with esters or hemiacetals the threo isomers 6 and 8 are formed predominantly (Table I).
