Syntheses of Chiral Fluorinated Molecules Featuring Multiple Stereocenters

Title:

Syntheses of Chiral Fluorinated Molecules Featuring Multiple Stereocenters

Schedule:

Date: 28^th September, 2023 (Thursday)

Time: 5:30 - 6:30 pm (HKT)

Venue: Lecture Theatre P2, Chong Yuet Ming Physics Building

Speaker:

Dr. Dominique Cahard

Research Director

CNRS, Univ Rouen Normandie

France

Abstract:

A decade ago, we embarked on the asymmetric construction of chiral carbon atoms featuring the trifluoromethylated motif through original approaches. Initial work on the isomerization of allylic alcohols furnished a protocole to prepare b-CF3 carbonyl compounds with a complete stereospecificity. In this work, we demonstrated for the first time a suprafacial enantiospecific 1,3-hydrogen atom transfer. Next, we studied various asymmetric transfer hydrogenations leading to simultaneous construction of up to three contiguous stereogenic centers under single or double dynamic kinetic resolution (DKR). Previously inaccessible chiral fluorinated alcohols were obtained by this method with very high enantioselectivities. Very recently, we developed a regio- and diastereoselective carbometalation of CF3-substituted cyclopropenes in which the CF3 group acts as a directing group in the carbometallation step. This simple strategy allows the preparation of polysubstituted (up to penta-) cyclopropyl rings possessing two adjacent quaternary carbon stereocenters with excellent diastereoselectivities. The enantioselective version was also investigated.

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