FRINK Linked Data Fragments server

Matches in SemOpenAlex for { <https://semopenalex.org/work/W1993908700> ?p ?o ?g. }

• W1993908700 endingPage "12330" @default.
• W1993908700 startingPage "12319" @default.
• W1993908700 abstract "The use of chiral auxiliaries is one of the most fundamental protocols employed in asymmetric synthesis. In the present study, stereoselectivity-determining factors in a chiral auxiliary-based asymmetric aldol reaction promoted by TiCl4 are investigated by using density functional theory methods. The aldol reaction between chiral titanium enolate [derived from Evans propionyl oxazolidinone (1a) and its variants oxazolidinethione (1b) and thiazolidinethione (1c)] and benzaldehyde is examined by using transition-state modeling. Different stereochemical possibilities for the addition of titanium enolates to aldehyde are compared. On the basis of the coordination of the carbonyl/thiocarbonyl group of the chiral auxiliary with titanium, both pathways involving nonchelated and chelated transition states (TSs) are considered. The computed relative energies of the stereoselectivity-determining C−C bond formation TSs in the nonchelated pathway, for both 1a and 1c, indicate a preference toward Evans syn aldol product. The presence of a ring carbonyl or thiocarbonyl group in the chiral auxiliary renders the formation of neutral TiCl3-enolate, which otherwise is energetically less favored as compared to the anionic TiCl4-enolate. Hence, under suitable conditions, the reaction between titanium enolate and aldehyde is expected to be viable through chelated TSs leading to the selective formation of non-Evans syn aldol product. Experimentally known high stereoselectivity toward Evans syn aldol product is effectively rationalized by using the larger energy differences between the corresponding diastereomeric TSs. In both chelated and nonchelated pathways, the attack by the less hindered face of the enolate on aldehyde through a chair-like TS with an equatorial disposition of the aldehydic substituent is identified as the preferred mode. The steric hindrance offered by the isopropyl group and the possible chelation are identified as the key reasons behind the interesting stereodivergence between Evans and non-Evans products normally reported for the title reaction. The application of an activation strain model on the critical TSs has been effective toward rationalizing the origin of stereoselectivity. Improved interaction energy between the reactants is found to be the key stabilizing factor for the lowest energy TS in both chelated and nonchelated pathways. The present study provides newer insights on the role of titanium(IV) toward modulating stereoselectivity in aldol reactions." @default.
• W1993908700 created "2016-06-24" @default.
• W1993908700 creator A5018528585 @default.
• W1993908700 creator A5061836817 @default.
• W1993908700 date "2010-08-13" @default.
• W1993908700 modified "2023-10-18" @default.
• W1993908700 title "Transition State Models for Probing Stereoinduction in Evans Chiral Auxiliary-Based Asymmetric Aldol Reactions" @default.
• W1993908700 cites W1586810352 @default.
• W1993908700 cites W1966182479 @default.
• W1993908700 cites W1968436252 @default.
• W1993908700 cites W1970714594 @default.
• W1993908700 cites W1978536813 @default.
• W1993908700 cites W1979059813 @default.
• W1993908700 cites W1979850841 @default.
• W1993908700 cites W1981451973 @default.
• W1993908700 cites W1985017113 @default.
• W1993908700 cites W1987121190 @default.
• W1993908700 cites W1997326966 @default.
• W1993908700 cites W2002270663 @default.
• W1993908700 cites W2003286577 @default.
• W1993908700 cites W2004027787 @default.
• W1993908700 cites W2005363003 @default.
• W1993908700 cites W2012866556 @default.
• W1993908700 cites W2014767176 @default.
• W1993908700 cites W2016180217 @default.
• W1993908700 cites W2019179169 @default.
• W1993908700 cites W2021159285 @default.
• W1993908700 cites W2021239011 @default.
• W1993908700 cites W2021571287 @default.
• W1993908700 cites W2027070364 @default.
• W1993908700 cites W2031335689 @default.
• W1993908700 cites W2036319937 @default.
• W1993908700 cites W2039583110 @default.
• W1993908700 cites W2040259918 @default.
• W1993908700 cites W2042677606 @default.
• W1993908700 cites W2044591029 @default.
• W1993908700 cites W2045063489 @default.
• W1993908700 cites W2045239086 @default.
• W1993908700 cites W2046021716 @default.
• W1993908700 cites W2046412723 @default.
• W1993908700 cites W2050469115 @default.
• W1993908700 cites W2053854247 @default.
• W1993908700 cites W2058236371 @default.
• W1993908700 cites W2058363175 @default.
• W1993908700 cites W2068617439 @default.
• W1993908700 cites W2068856008 @default.
• W1993908700 cites W2069041053 @default.
• W1993908700 cites W2069377704 @default.
• W1993908700 cites W2071684174 @default.
• W1993908700 cites W2076840425 @default.
• W1993908700 cites W2077307846 @default.
• W1993908700 cites W2077897012 @default.
• W1993908700 cites W2078394136 @default.
• W1993908700 cites W2080194496 @default.
• W1993908700 cites W2081214633 @default.
• W1993908700 cites W2082917109 @default.
• W1993908700 cites W2086957099 @default.
• W1993908700 cites W2089637769 @default.
• W1993908700 cites W2091483872 @default.
• W1993908700 cites W2094642658 @default.
• W1993908700 cites W2102286885 @default.
• W1993908700 cites W2103169163 @default.
• W1993908700 cites W2105961053 @default.
• W1993908700 cites W2116234857 @default.
• W1993908700 cites W2121112265 @default.
• W1993908700 cites W2124970362 @default.
• W1993908700 cites W2128949728 @default.
• W1993908700 cites W2137517652 @default.
• W1993908700 cites W2140288236 @default.
• W1993908700 cites W2140886907 @default.
• W1993908700 cites W2143981217 @default.
• W1993908700 cites W2154604177 @default.
• W1993908700 cites W2159816194 @default.
• W1993908700 cites W2166423820 @default.
• W1993908700 cites W2171445884 @default.
• W1993908700 cites W2912537323 @default.
• W1993908700 cites W2949184868 @default.
• W1993908700 cites W2949212547 @default.
• W1993908700 cites W2949563576 @default.
• W1993908700 cites W2950090908 @default.
• W1993908700 cites W2950544043 @default.
• W1993908700 cites W2951373270 @default.
• W1993908700 cites W2952187096 @default.
• W1993908700 cites W2952444396 @default.
• W1993908700 cites W3005186991 @default.
• W1993908700 cites W2035743416 @default.
• W1993908700 doi "https://doi.org/10.1021/ja101913k" @default.
• W1993908700 hasPubMedId "https://pubmed.ncbi.nlm.nih.gov/20707387" @default.
• W1993908700 hasPublicationYear "2010" @default.
• W1993908700 type Work @default.
• W1993908700 sameAs 1993908700 @default.
• W1993908700 citedByCount "53" @default.
• W1993908700 countsByYear W19939087002012 @default.
• W1993908700 countsByYear W19939087002013 @default.
• W1993908700 countsByYear W19939087002014 @default.
• W1993908700 countsByYear W19939087002015 @default.
• W1993908700 countsByYear W19939087002016 @default.
• W1993908700 countsByYear W19939087002017 @default.

• next