134877-09-1Relevant articles and documents
Enantioselective Diels-Alder Reactions of Carboxylic Ester Dienophiles Catalysed by Titanium-Based Chiral Lewis Acid
Choughule, Yogesh K.,Patwardhan, Anand V.
, p. 921 - 926 (2016/07/06)
A new titanium-based chiral Lewis acid 1 has been developed using (1R,2R)-1,2-bis-(2-methoxyphenyl)-ethane-1,2-diol as a chiral vicinal diol ligand. This chiral catalyst was found to exhibit uniformly high enantioselectivity towards carboxylic ester dienophiles in Diels-Alder reactions. The chiral vicinal ligand (1R,2R)-1,2-bis-(2-methoxyphenyl)-ethane-1,2-diol is inexpensive and is easily accessible.
Enzymes in organic synthesis 49. Resolutions of racemic monocyclic esters with pig liver esterase
Toone,Jones
, p. 207 - 222 (2007/10/02)
Pig liver esterase (PLE)- catalyzed hydrolyses of the racemic methyl esters of cyclobutane-, cyclohexane-, and cyclohex-4-ene-carboxylic acids bearing cis-2-methyl or cis-2-bromomethyl substituents are highly stereoselective, giving the corresponding acid products of ≥ 97% ee. The stereoselectivity of the enzyme exhibits the expected reversal for such compounds, with the absolute configurations of the cyclobutane and cyclohexame acids being of the opposite absolute configuration type, and cyclopentane substrates such as cis-1-carbomethoxy-2-methylcyclopentane representing the change-over structures and giving products of only 22%ee. This stereoselectivtiy reversal, and the absolute configurations preferred, are as predicted by the recently proposed active site model for the enzyme.
