Stereospecific Isomerization of Allylic Halides via Ion Pairs with Induced Noncovalent Chirality
Samuel Martinez-Erro1, Víctor García-Vázquez1, Amparo Sanz-Marco1
1Department of Organic Chemistry, Stockholm University, Stockholm 10691, Sweden.
Abstract:
A regioselective protocol for the synthesis of substituted allylic chlorides, bromides, and fluorides has been established. Remarkably, the method can be applied to the enantioselective synthesis of challenging chiral allylic chlorides. When the allylic halides are treated with the base triazabicyclodecene as the catalyst, a [1,3]-proton shift takes place, giving the corresponding vinyl halides in excellent yields with excellent Z:E ratios. Furthermore, the [1,3]-proton shift takes place with an outstanding level of chirality transfer from chiral allylic alcohols (≤98%) to give chiral trifluoromethylated vinyl chlorides.
Related Concept Videos
01:33Radical Halogenation: Stereochemistry
Halogenation to form a new chiral center:
02:32Stereoisomers
02:17Regioselectivity of Electrophilic Additions to Alkenes: Markovnikov's Rule
The hydrohalogenation of an unsymmetrical alkene can yield two haloalkane products, depending on which vinylic carbon takes up the halogen. However, one product usually predominates, where hydrogen adds to the vinylic carbon bearing the...
02:52Stereoisomerism
Isomers are different chemical species that have the same chemical formula.
Transition metal complexes often exist as geometric isomers, in which the same atoms are connected through the same types of bonds but with differences in their orientation in space. Coordination complexes with two different ligands in the cis and trans positions from a ligand of interest form isomers. For example, the octahedral [Co(NH3)4Cl2]+ ion has two isomers (Figure 1) In the cis...
02:34Regioselectivity and Stereochemistry of Acid-Catalyzed Hydration
02:33Stereoisomerism of Cyclic Compounds