High Diversity on Simple Substrates: 1,4-Dihalo-2-butenes and Other Difunctionalized Allylic Halides for Copper-Catalyzed SN2′ Reactions

Enantioselective allylic alkylation with an organomagnesium reagent catalyzed by copper thiophene carboxylate (CuTC) was carried out on difunctionalized substrates, such as commercially available 1,4‐dichloro‐2‐butene and 1,4‐dibromo‐2‐butene, and on similar compounds of higher substitution pattern...

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Bibliographic Details
Published in:Chemistry : a European journal 2008-11, Vol.14 (34), p.10615-10627
Main Authors: Falciola, Caroline A., Alexakis, Alexandre
Format: Article
Language:English
Subjects:
allylic compounds
arylation
asymmetric catalysis
copper
nucleophilic substitution
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Summary:Enantioselective allylic alkylation with an organomagnesium reagent catalyzed by copper thiophene carboxylate (CuTC) was carried out on difunctionalized substrates, such as commercially available 1,4‐dichloro‐2‐butene and 1,4‐dibromo‐2‐butene, and on similar compounds of higher substitution pattern of the olefin for the formation of all‐carbon chiral quaternary centers. The high regioselectivity obtained throughout the reactions favored good regiocontrol for the addition of phenyl Grignard reagents. Other difunctionalized substrates (allylic ethers and allylic alcohols) also underwent asymmetric SN2′ substitution. Tunable chiral synthons: From simple, small, and commercially available starting bishalo substrates (see scheme), one can reach high enantioselectivities of up to 94 % ee and perfect regioselectivities. These chiral products undergo nucleophilic or electrophilic transformation upon their remaining halide in a stereoretentive fashion.
ISSN:0947-6539
1521-3765
DOI:10.1002/chem.200801309