1502-79-0Relevant academic research and scientific papers
Samarium diiodide-promoted diiodomethylation of carbonyl compounds with iodoform. Synthetic applications of diiodoalcohols
Concellon, Jose M.,Bernad, Pablo L.,Perez-Andres, Juan A.
, p. 1409 - 1412 (2007/10/03)
A rapid and effective diiodomethylation of carbonyl compounds using SmI2 and iodoform is described. Transformations of the obtained diiodoalcohols 2 into α-iodoaldehydes 5 and α-hydroxyacids 6 is also reported.
Enantiopreference of Lipase from Pseudomonas cepacia toward Primary Alcohols
Weissfloch, Alexandra N. E.,Kazlauskas, Romas J.
, p. 6959 - 6969 (2007/10/03)
We propose an empirical rule that predicts which enantiomer of primary alcohol reacts faster in reactions catalyzed by lipase from Pseudomonas cepacia (PCL).This rule, based on the size of the substituents at the stereocenter, shows an 89percent reliability (correct for 54 of 61 examples).This rule is not reliable for primary alcohols that have an oxygen atom attached to the stereocenter; we excluded these alcohols from the tally above.Surprisingly, the sense of enantiopreference of PCL toward primary alcohols is opposit to its enantiopreference toward secondary alcohols.That is, the OH of secondary alcohols and the CH2OH of primary alcohols point in opposite directions.We suggest, however, that this opposite orientation does not imply a different position of the substituents in the active site of the lipase.Instead, PCL accommodates the extra CH2 in primary alcohols as a kink between the stereocenter and the oxygen which allows a similar position of the alcohols by increasing the diffrence in the size of the substituents but did not find a consistent increase in enantioselectivity.We suggest that high enantioselectivity toward primary alcohols requires not only a significant difference in the size of the substituents, but also control of the conformation along the C(1)-C(2) bond.
Acetolysis of 2-Aryl-1-methylpropyl Systems: Mechanism of the Formation of the Retained Product without Neighbouring Group Participation
Kinoshita, Tomomi,Takemoto, Masaki,Shibayama, Koichi,Takeuchi, Ken'ichi
, p. 2153 - 2174 (2007/10/02)
threo-2--1-(13C)methylpropyl p-bromobenzenesulphonate (threo-(13C)1-OBs) has been solvolyzed in acetic acid to give rise to the retained threo-1-OAc which contains a small amount of threo-(13C)1-OAc accompanying no 13C-scrambling.At 75percent conversion, the isomerized erythro-1-OBs has been obtained along with the unchanged threo-1-OBs.Also, the erythro-1-OTs has been found at 50percent conversion in the presence of NaOTs.These stereochemical results indicate strongly that the acetate with the retained configuration accompanying no 13C-scrambling is formed via isomerization of the substrate by inversive anion exchange and a successive ks pathway with configurational inversion.Such a retained product was not detected in the acetolysis of threo-1-methyl-2-phenylpropyltoluene-p-sulphonate with no electron withdrawing substituent.
Studies on the Regioselectivities in the Oxidation of Simple Alkyl Aromatic Hydrocarbons by Molecular Oxygen
Pritzkow, Wilhelm,Thomas, Gerda,Willecke, Lothar
, p. 847 - 851 (2007/10/02)
The products of the autoxidation of various simple alkyl aromatic hydrocarbons were reduced by LiAlH4, and the alcohols formed were determined by gas chromatography.In the cases of 2-phenylbutane, 3-phenylpentane, and 2-p-tolylbutane a considerable fragmentation of the intermediate tertiary alkoxy radicals was proved.On the basis of the analytical results relative reaction rates of the various C-H bonds in the hydrocarbons studied were calculated.It is shown that the attack at C-H bonds which are not activated by the aromatic nucleus cannot be neglected and may be of great importance for the kinetics of the oxidation of alkyl aromatic hydrocarbons.
