467443-01-2Relevant articles and documents
PROCESS FOR PREPARING EZETIMIBE INTERMEDIATE
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Paragraph 0036; 0037, (2016/11/07)
The present invention refers to [...] which can inhibit the cholesterol absorption and are (ezetimibe) used in the manufacture of an intermediate manufacturing method relates to compounds of formula 4, a chelatable metal compounds, and metal of formula 2 in one direction so that at step low id id compound of formula 3 to the asymmetrically reducing according to including of the present invention manufacturing method, a method that of the prior art compared to compounds of formula 4 economically, purity can be produced: Said in formula, The X and Ph as defined during specification.
Enantioselective reduction of α-substituted ketones mediated by the boronate ester TarB-NO2
Eagon, Scott,Ball-Jones, Nicholas,Haddenham, Dustin,Saavedra, Jaime,Delieto, Cassandra,Buckman, Matthew,Singaram, Bakthan
supporting information; experimental part, p. 6418 - 6421 (2010/12/30)
A facile and mild reduction procedure is reported for the preparation of chiral secondary alcohols prepared from α-substituted ketones using sodium borohydride and the chiral boronate ester (l)-TarB-NO2. Direct reduction of substituted ketones bearing Lewis basic heteroatoms generally provided secondary alcohols of only modest enantiomeric excess likely due to either competition between the target carbonyl and the functionalized sidechains at the Lewis acidic boron atom in TarB-NO2 or the added steric bulk of the α-sidechain. As an alternative method, these substrates were synthesized using TarB-NO2 via a two-step procedure involving the reduction of an α-halo ketone to a chiral terminal epoxide, followed by regioselective/regiospecific epoxide opening by various nucleophiles. This procedure provides access to a variety of functionalized secondary alcohols including β-hydroxy ethers, thioethers, nitriles, and amines with enantiomeric excesses of 94% and yields up to 98%.
Mild and expedient asymmetric reductions of α,β-unsaturated alkenyl and alkynyl ketones by TarB-NO2 and mechanistic investigations of ketone reduction
Eagon, Scott,Delieto, Cassandra,McDonald, William J.,Haddenham, Dustin,Saavedra, Jaime,Kim, Jinsoo,Singaram, Bakthan
experimental part, p. 7717 - 7725 (2011/01/05)
A facile and mild reduction procedure is reported for the preparation of chiral allylic and propargyl alcohols in high enantiomeric purity. Under optimized conditions, alkynyl and alkenyl ketones were reduced by TarB-NO 2 and NaBH4 at 25 °C in 1 h to produce chiral propargyl and allylic alcohols with enantiomeric excesses and yields up to 99%. In the case of α,β-unsaturated alkenyl ketones, α-substituted cycloalkenones were reduced with up to 99% ee, while more substituted and acyclic derivatives exhibited lower induction. For α,β-ynones, it was found that highly branched aliphatic ynones were reduced with optimal induction up to 90% ee, while reduction of aromatic and linear aliphatic derivatives resulted in more modest enantioselectivity. Using the (l)-TarB-NO2 reagent derived from (l)-tartaric acid, we routinely obtained highly enantioenriched chiral allylic and propargyl alcohols with (R) configuration. Since previous models and a reduction of a saturated analogue predicted propargyl products of (S) configuration, a series of new mechanistic studies were conducted to determine the likely orientation of aromatic, alkenyl, and alkynyl ketones in the transition state.
Intramolecular Nicholas reactions in the synthesis of dibenzocycloheptanes. Synthesis of allocolchicine NSC 51046 and analogues and the formal synthesis of (-)-allocolchicine
Djurdjevic, Sinisa,Yang, Fei,Green, James R.
experimental part, p. 8241 - 8251 (2011/03/18)
The preparation of dibenzocycloheptyne-Co2(CO)6 complexes by intramolecular Nicholas reactions of biaryl-2-propargyl alcohol-Co2(CO)6 derivatives is described. Reductive decomplexation of the dibenzocycloheptyne
A NEW PROCESS FOR THE PREPARATION OF MONTELUKAST
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Page/Page column 25-26, (2008/12/05)
The present invention describes a novel process for the preparation of montelukast acid, and its pharmaceutically acceptable salts and esters.
Asymmetric reductions using the chiral boronic ester TarB-H: a practical and inexpensive procedure for synthesizing chiral alcohols
Eagon, Scott,Kim, Jinsoo,Yan, Katie,Haddenham, Dustin,Singaram, Bakthan
, p. 9025 - 9029 (2008/03/18)
Chiral alcohols are prepared in high enantiomeric excesses using an inexpensive and easily synthesized tartaric acid derived boronic ester (TarB-H) with sodium borohydride. The phenylboronic acid could be recovered quantitatively using a simple extraction with sodium hydroxide and diethyl ether. The optimized TarB-H system was used to reduce aromatic and aliphatic ketones in an open flask to chiral alcohols with enantiomeric excesses up to 99%.
Enantioselective reduction of aliphatic ketones using NaBH4 and TarB-NO2, a chiral boronic ester
Kim, Jinsoo,Singaram, Bakthan
, p. 3901 - 3903 (2007/10/03)
High enantioselectivities are obtained using a tartaric acid-derived boronic ester (TarB-NO2) in combination with NaBH4 for the asymmetric reduction of aliphatic ketones. The resulting alcohols are obtained in enantiomeric excesses ranging from 56% to 94%.
Chiral styrene oxides from α-haloacetophenones using NaBH4 and TarB-NO2, a chiral Lewis acid
Cordes, David B.,Kwong, Tracey J.,Morgan, Kellie A.,Singaram, Bakthan
, p. 349 - 351 (2007/10/03)
High enantioselectivities are obtained for the preparation of chiral styrene oxides through reduction of α-haloacetophenones using TarB-NO 2 reagent and the inexpensive and mild reducing agent NaBH 4. The epoxides are easily obtained in up to 95% ee through routine acid-base workup of the product alcohols. Either the (R) or (S) epoxide can be obtained by using the appropriate l- or d-tartaric acid starting material in the TarB-NO2 reagent.
Asymmetric reduction of ketones under mild conditions using NaBH 4 and TarB-NO2: An efficient and unusual chiral acyloxyborohydride reducing system
Cordes, David B.,Nguyen, Thao M.,Kwong, Tracey J.,Suri, Jeff T.,Luibrand, Richard T.,Singaram, Bakthan
, p. 5289 - 5295 (2007/10/03)
High enantioselectivities are obtained for the reduction of a series of ketones using the inexpensive and mild reducing agent NaBH4 with TarB-NO2 (1). This easily prepared tartaric acid-based reagent combines a Lewis acid with carboxylic acids in a single bifunctional reagent. When combined with NaBH4, the resulting chiral acyloxyborohydride mediates the reduction of aromatic ketones to provide the product alcohols in enantiomeric excesses of 93-98%. Several aliphatic ketones were also reduced with moderate to excellent enantioselectivity. A unique mechanism is provided with supporting calculations for the proposed active species and transition state. Wiley-VCH Verlag GmbH & Co. KGaA, 2005.
Enantioselective reduction of aryl ketones using LiBH4 and TarB-X: A chiral Lewis acid
Suri, Jeff T,Vu, Truong,Hernandez, Arturo,Congdon, Julie,Singaram, Bakthan
, p. 3649 - 3652 (2007/10/03)
High enantioselectivities are obtained using a tartaric acid-derived boronate ester in combination with lithium borohydride for asymmetric reduction of aryl ketones. The chiral Lewis acid, TarB-X, is easily prepared in 1 h, and the resulting alcohols are
