1000681-40-2Relevant academic research and scientific papers
Kinetic resolution of unsaturated amides in a chlorocyclization reaction: Concomitant enantiomer differentiation and face selective alkene chlorination by a single catalyst
Jaganathan, Arvind,Staples, Richard J.,Borhan, Babak
, p. 14806 - 14813 (2013)
The first example of a kinetic resolution via chlorofunctionalization of olefins is reported. The enantiomers of racemic unsaturated amides were found to have different hydrogen-bonding affinities for chiral Lewis bases in numerous solvents. This interaction was exploited in developing a kinetic resolution of racemic unsaturated amides via halocyclization. The same catalyst serves to both sense chirality in the substrate as well as mediate a highly face-selective chlorine delivery onto the olefin functionality, resulting in stereotriad products in up to 99:1 dr and up to 98.5:1.5 er. The selectivity factors were typically greater than 50 to allow for the simultaneous synthesis of both the products and unreacted substrates in highly enantioenriched form at yields approaching 50%. The reaction employs catalytic amounts (≤0.50 mol %) of a commercially available and recyclable organocatalyst.
Asymmetric allylboration of acyl imines catalyzed by chiral diols
Lou, Sha,Moquist, Philip N.,Schaus, Scott E.
, p. 15398 - 15404 (2008/09/18)
Chiral BINOL-derived diols catalyze the enantioselective asymmetric allylboration of acyl imines. The reaction requires 15 mol % (S)-3,3′-Ph2-BINOL as the catalyst and allyldiisopropoxyborane as the nucleophile. The reaction products are obtained in good yields (75-94%) and high enantiomeric ratios (95:5-99.5:0.5) for aromatic and aliphatic imines. High diastereoselectivities (diastereomeric ratio > 98:2) and enantioselectivities (enantiomeric ratio > 98:2) are obtained in the reactions of acyl imines with crotyldiisopropoxyboranes. This asymmetric transformation is directly applied to the synthesis of Maraviroc, the selective CCR5 antagonist with potent activity against HIV-1 infection. Mechanistic investigations of the allylboration reaction including IR, NMR, and mass spectrometry studies indicate that acyclic boronates are activated by chiral diols via exchange of one of the boronate alkoxy groups with activation of the acyl imine via hydrogen bonding.
