60208-56-2Relevant academic research and scientific papers
Deracemizing α-Branched Carboxylic Acids by Catalytic Asymmetric Protonation of Bis-Silyl Ketene Acetals with Water or Methanol
Mandrelli, Francesca,Blond, Aurélie,James, Thomas,Kim, Hyejin,List, Benjamin
, p. 11479 - 11482 (2019/07/18)
We report a highly enantioselective catalytic protonation of bis-silyl ketene acetals. Our method delivers α-branched carboxylic acids, including nonsteroidal anti-inflammatory arylpropionic acids such as Ibuprofen, in high enantiomeric purity and high yields. The process can be incorporated in an overall deracemization of α-branched carboxylic acids, involving a double deprotonation and silylation followed by the catalytic asymmetric protonation.
9-Borabicyclo[3.3.2]decanes and the asymmetric hydroboration of 1,1-disubstituted alkenes
Gonzalez, Ana Z.,Roman, Jose G.,Gonzalez, Eduvigis,Martinez, Judith,Medina, Jesus R.,Matos, Karl,Soderquist, John A.
supporting information; experimental part, p. 9218 - 9219 (2009/02/02)
The syntheses of the optically pure asymmetric hydroborating agents 1 (a, R = Ph; b, R = TMS) in both enantiomeric forms are reported. These reagents are effective for the hydroboration of cis-, trans- and trisubstituted alkenes. More significantly, they exhibit unprecedented levels of selectivity in the asymmetric hydroboration of 1,1-disubstituted alkenes (28-92% ee), a previously unanswered challenge in the nearly 50 year history of this reagent-controlled process. For example, the hydroboration of α-methylstyrene with 1a produces the corresponding alcohol 6f in 78% ee (cf., Ipc2BH, 5% ee). Suzuki coupling of the intermediate adducts 5 produces the nonracemic products 7 very effectively (50-84%) without loss of optical purity. Copyright
Stereochemical Dynamics of Aliphatic Hydroxylation by Cytochrome P-450
White, Ronald E.,Miller, John P.,Favreau, Leonard V.,Bhattacharyya, Apares
, p. 6024 - 6031 (2007/10/02)
Previous studies on the stereochemistry of hydroxylation by cytochrome P-450 enzymes have been contradictory and confusing.Therefore, the hydroxylation of four isotopically substituted phenylethane substrates has been examined with a single isozyme of rabbit liver microsomal cytochrome P-450.In each case the corresponding 1-phenylethanol was essentially the only product.With ordinary phenylethane, the product was 48percent R-1-phenylethanol and 52percent the S isomer.With (R)-phenylethane-1-d, the product was 42percent R alcohol, while with (S)-phenylethane-1-d the product was 70percent R alcohol.When the substrate was phenylethane-1,1-d2, 50percent R alcohol was produced.The alcohols from the single-deuterium-substituted substrates were highly enriched in deuterium, indicating the operation of a large deuterium isotope effect on hydrogen removal.Most importantly, 23-40percent of the hydroxylation events resulted in alcohol with configuration opposite to that of the original hydrocarbon substrate.These "crossover" events require the intermediacy of a discrete tricoordinate carbon intermediate.These data unambiguously demonstrate that hydroxylation stereospecificity must be enforced by the surrounding protein tertiary structure and is not an inherent feature of the cytochrome P-450 reaction mechanism.
ANTI STEREOCHEMISTRY IN PROTODESILYLATION OF AN OPTICALLY ACTIVE ALLYLSILANE WITH TRRIFLUOROACETIC ACID-D
Hayashi, Tamio,Ito, Hiroshi,Kumada, Makoto
, p. 4605 - 4606 (2007/10/02)
SE' reaction of (R)-(E)-1,3-diphenyl-3-trimethylsilylpropene with trifluoroacetic acid-d proceeded with anti stereochemistry to give (R)-(E)-1,3-diphenylpropene-3-d.
